As our flight training progresses as a student pilot, we start flying away from our local flying area and airport to new airports.Apart from learning new skills in flying, a student gets to learn how to file a flight plan, its importance and the role of flight plans in aviation. A flight plan is simply advance notice of a pilot’s intentions for a flight in terms of route (including departure
and destination), cruising level and speed and information about the crew and passengers.

This service of filing a flight plan keeps the Air traffic Service Units informed that you will be out flying today and from where and what time you plan to depart and land.In the unlikely event of you having to perform a landing in the bushes or to an off the route airfield and having no communication, the air traffic services will inform the search and rescue team to find you .

International Civil Aviation Organization (ICAO) aims to keep aviation goals, standards and practices common between most countries. Hence, the domestic flight plan in countries is in line with the flight plan published by the ICAO. The major differences between the domestic flight plan and ICAO one is that the latter is more detailed and requires details about your aircraft’s navigation systems,survival equipment, transponder details etc in depth.

The above image is a copy of an ICAO flight plan that is submitted to the Air Traffic Service (ATS) units. The items from number 7 to 18 are necessary to be completed and if deemed compulsory for by ATS, the item 19 needs to be filled as well.

ITEM NO 7: Aircraft Identification

  • Aircraft Identification should include a maximum of 7 alphanumeric characters without any symbol.There are two ways of filling item number 7:
  • The first way is using an ICAO approved name of the aircraft plus the flight number.For example, AI144 (Air India+144) or KLM511 (KLM+511).
  • The second way is if the aircraft does not have ICAO approved name,then we use the registration number to fill item number 7 , for example 4XBCD or N2567GA.

ITEM NO 8: Flight Rules and Type of Flight

  • Item No 8 has 2 boxes to fill, the left one is the flight rules followed by the aircraft and the right one is the type of flight it is going to be.
  • The flight rules box can be inserted with an of the following 4 letters to determine the category of flight rules followed:
    1. I- if the entire flight will be operated under IFR (Instrument Flight Rules) conditions
    2. V-if the entire flight will be operated under VFR (Visual Flight Rules) conditions
    3. Y-if the flight will initially be operated under IFR and then will be changed to VFR
    4. Z-if the flight will initially be operated under VFR and then will be changed to IFR
  • NOTE: It can get confusing sometimes to remember all the letters and what category they mean.For a quick way to never confuse yourself between Y or Z, remember the phrase (Y IFR WHEN YOU CAN FLY VFR)
  • The type of flight box can be inserted with an of the following 4 letters to determine the category of flight rules followed:
    1. S-Scheduled Flights
    2. N-Non Scheduled Flight
    3. G-General Aviation
    4. M-Military Aviation
    5. X-If any other than the above categories

ITEM NO 9: Number and Type of Aircraft and Wake Turbulence Category

  • The number of aircraft box needs to be inserted if more than 1, for example army formation flying can have 5.Therefore, insert 05.
  • The type of aircraft box is filled with 2 to 4 characters. For example, A320 or B737.
  • The wake turbulence category is filled with one of the following letters after the oblique sign:
    1. H — HEAVY, to indicate an aircraft type with a maximum certificated take-off mass of 136 000 kg or more;
    2. M — MEDIUM, to indicate an aircraft type with a maximum certificated take-off mass of less than 136 000 kg but more than 7 000 kg;
    3. L — LIGHT, to indicate an aircraft type with a maximum certificated take-off mass of 7 000 kg or less.

ITEM NO 10: Equipment and Capabilities

  • The equipment box is filled by the presence of relevant serviceable equipment onboard and it also depends on the flight crew qualifications.
  • The usual letters used to fill this box are:
    • N if no COM/NAV/approach aid equipment for the route to be flown is carried, or the equipment is unserviceable.
    • S if standard COM/NAV/approach aid equipment for the route to be flown is carried and serviceable.If the letter S is used, standard equipment is considered to be VHF RTF, VOR and ILS, unless another combination is prescribed by the appropriate ATS authority.
  • Any other extra equipment carried on board will be notified in the other information box,that is, item 18.To know more about the letters used for mentioning the details of other equipment on board:https://ops.group/blog/wp-content/uploads/2017/03/ICAO-Doc4444-Pans-Atm-16thEdition-2016-OPSGROUP.pdf

ITEM NO 13: Departure Aerodrome and Time

  • In the departure aerodrome box , we mention the ICAO approved name of the aerodrome for example VABB (Mumbai airport) or YSSY ( Sydney airport).
  • If the airport does not have an ICAO approved code we insert ‘ZZZZ’ in the departure aerodrome box and mention the name of the airport in the other information box, that is, box 18.
  • The box of time needs to be inserted with ESTIMATED OFF BLOCKS TIME (EOBT) in UTC.The off blocks time denotes the time at which the aircraft moves forward with its own power.


  • Cruising speed (maximum of 5 characters) is the True Air speed for the first or the whole cruising portion of the flight.
    1. If the speed is mentioned in knots then it is expressed as N followed by 4 figures ( eg :N0400 if the speed is 400 knots)
    2. If the speed is mentioned in kilometres per hour, expressed as K followed by 4 figures (eg: K0800 if the speed is 800 km/hr)
    3. True Mach Number expressed as M followed by 3 figures (eg M082) can also be inserted to the nearest hundredth of the unit mach.
  • Cruising Level (maximum of 5 characters) is the planned cruising level to be flown for the first part of the flight or the entire flight.
    1. Flight level can be expressed as F followed by 3 figures for eg F330.
    2. The level can be expressed in terms of altitude in hundreds of feet, expressed as A followed by 3 figures for eg A100.
    3. Altitude in tens of metres, expressed as M followed by 4 figures (e.g. M0840).
  • The route box includes information such as changes in speed, level or flight routes.All ATS routes have names. For example, domestic flights are given by the code W.If there are no code designators assigned for the point, we define the position with the help of a reference point and the co ordinates from that point in degrees and minutes.In case any changes are to be made to the route , the sequence in which it should be mentioned is:
    • Name of the Waypoint
    • Speed of aircraft
    • Flight level of aircraft
    • Name of airway.

ITEM NO 16:Destination Aerodrome, Total Estimated Elapsed Time and Destination Alternate Aerodrome

  • The destination aerodrome box if filled in a similar way as the departure aerodrome box.The ICAO approved 4 letter indicator of the aerodrome needs to be mentioned and if the does not have one, then we fill the box with ZZZZ and mention the name in box 18.
  • The total estimated elapsed time is the time from take off to the time overhead the navigational facility at destination in case of IFR.
  • The total estimated elapsed time is the time taken from take off time to time overhead the destination in case of VFR.
  • There can be two alternate aerodrome options available for diverting if necessary and are to be inserted in the same way as the destination aerodrome. Pilots are however also allowed to divert to a third unspecified aerodrome in case both alternates are below minimum.

ITEM NO 18: Other Information

ITEM NO 19: Supplementary Information

  • Endurance is the total fuel on board entered as a 4 figure group giving the fuel endurance in hours and minutes ( for eg 0330)
  • Total Persons on Board is the total number of persons, that is, passengers and crew are to be entered if required by the appropriate ATS authority.If the number of persons on board are not known at the time of filing the flight plan, TBN is to be inserted and the commander can notify the ATC about the real number at the time of start up.
  • In the Emergency Radio , Survival Equipment,Jackets and Dinghies boxes, the items that are not available or serviceable need to be crossed out.For example, cross out V if VHF on frequency 121.5 MHz is not available or cross out F if life jackets are not equipped with fluorescene.
  • Remarks box: Cross out the indicator N if the there are no remarks that are needed to be inserted or indicate any other survival equipment carried and any other remarks regarding survival equipment.
  • Pilot in Command:Name of the PIC as per license needs to be inserted and if both pilots have the same name, write the license number under the name.

Fact of the Week

Cargo Airlines are Airlines dedicated to the transport Valuable Freights, Some of the Cargo Airlines are Subsidiaries of Larger Passenger Airlines, most of the Cargo Airlines owned by Logistics Services Companies. Cargo Airplanes are specially designed for Cargo Services to Carry Heavy Goods, Fedex is the Largest Cargo Airlines in the World with 688 Fleet and 67 in new order. There are Hundreds of Cargo Airlines in the World with main Aim of Cargo Transportation. It is hard or nearly inconceivable to achieve any international trading, global export/import processes, international shifting of raw materials/products and constructing without a professional logistical support. Airplanes are the Fastest and Saves huge time for passengers and to delivers the Goods to the respective Places.

There are a few more topics related to the flight pans such as Repetitive Flight Plans (RPLS) which we can cover in a separate blog post. I hope you found this post informative and could gain some knowledge out of it from the world of aviation.Please do not forget to share this post with your fellow aviation lovers and drop a comment or a like as well. Until next week, stay safe and stay healthy.

Your Co Pilot


Critical Point

The main purpose of commercial aviation is getting people from varied parts of the globe closer. Qantas airplane in October last year, a Boeing 787-9 covered roughly 10,000 miles during its journey from New York to Sydney. The aircraft was in the air for a non stop 19 hrs and 16 minutes.These figures are staggering and long haul flights look more and more promising with the innovations of these aircraft’s in the future post the pandemic.The most important point to take out of this for an aviation enthusiast is how safe is the airplane when it is flying for long hours continuously in the air?

There are a number of failures that can occur during long haul flights and with the help of alternate airfields on the route, a pilot can take a decision to divert and land at one of the alternates.The big question is what if there are no alternates on the route or on one of the long oceanic legs of the flight? The answer is to that is the Critical Point calculated by pilots before their flight.

What is Critical Point

Critical Point (CP) also know known as Point Of Equal Time (PET) is the decision point between two airfields from which it would take the same time to fly to either airfield.In other words, CP or ETP is a geographical point in the flight where the aircraft would have the same flying time to continue on to a given airport or to turn back to another suitable airfield.

The knowledge of CP enables the pilot to decide which way would it be quicker for him to proceed either to the destination or return to the place of departure if they face a time critical problem such as cabin fire or an flight medical emergency.

NOTE: Before you read any further, I would highly recommend having a quick look at the Wind Triangle post in case you haven’t WIND TRIANGLE. The study of Critical Point requires concepts from the wind triangle that would help us in calculating the calculating the Ground speed so please check that out.

Operative Points

1.Lets consider a route from point A to point B which is 200 NM long. Our aircraft has a TAS of 100 knots and there are no winds. In this scenario, the critical point or point of equal time is the point of equal distance, that is 100 NM. What this shows that at the 100 NM mark, the time to destination or time to return back to departure airfield would be same.

2.Lets take the same example as above and consider a headwind of 20 knots.With a 20 knots headwind, the ground speed outwards (GS out) from A to B will reduce by 20 knots and become 80 knots and if you consider the opposite, that is if you return to A and direction of travel is from B to A then your ground speed will increase from 100 to 120 knots and we will call this as ground speed home (GS home).Hence as the GS home is more than GS out, the CP moves forward than what it was in still air conditions.As we saw in this example, it is safe to say that in case of headwind component, distance to CP will always be more than mid way.

3.Lets take the same example as above and consider a tailwind of 20 knots.With a 20 knots tailwind, the ground speed outwards (GS out) from A to B will increase by 20 knots and become 120 knots and if you consider the opposite, that is if you return to A and direction of travel is from B to A then your ground speed will decrease from 100 to 80 knots and we will call this as ground speed home (GS home).Hence as the GS out is more than GS home, the CP moves backward than what it was in still air conditions.As we saw in this example, it is safe to say that in case of tailwind component, distance to CP will always be less than mid way.

From the above points 2 and 3, the effect of a headwind and tailwind makes the critical point move in the direction on the wind .

4.We have addressed the effect of wind on the Critical Point but how do we know the distance to the CP (DCP) from the point we are calculating it and the time to CP. Lets consider we are traveling a distance ‘D’ from A to B and we know our TAS and winds. With the help of our TAS and winds we can calculate Ground speed.If we want to calculate our CP from position A then the ground speed from A to CP can be termed as GS OUT (O) and the ground speed from CP to A can be termed as GS HOME (H).The distance and time to CP can be found out by simple formulas as shown in the picture.

5.To get used to the calculating the DCP and time to CP we shall consider an example. Total distance from A to B is 750 NM. The aircraft TAS is 250 knots with with a tailwind of 30 knots on departure. Calculate the distance and time to CP?

6.There might be instances where the winds are directly abeam (90 degrees) to your track. In such cases, the distance to CP will always be midway and whether we proceed outbound or inbound, both ways the aircraft will face headwind.

Lets consider an example, with our route distance being 270 NM. The track of our flight is 030 degrees and the wind is coming from 120 degrees (90 degrees to the track) at 35 knots. The true air speed is 125 knots. Find the distance to CP and time to CP?

Even when we have a look at the picture on the right, the calculations show us the same thing that the critical point is mid way of the total distance.

In this weeks post we covered a very important topic of flight planning that is used by pilots.I hope you liked reading the post and gained some insight from it. Please feel free to email me or post in the comments section, any aviation related topics you would like to gain knowledge on. Until next week, stay safe and stay healthy.


Vertical Speed Indicator

Instruments in an aircraft are priceless for pilots. They are specially trained under the hood to get used to the instruments without looking outside the aircraft and understanding how the aircraft responds while flying only on instruments.After a student pilot has got used to the attitudes that he needs to set while flying visually with the horizon, he gets introduced to basic instrument flying.

In order to safely fly any aircraft, a pilot must understand how to interpret and operate the flight instruments. The pilot also needs to be able to recognize associated errors and malfunctions of these instruments.When a pilot understands how each instrument works and recognizes when an instrument is malfunctioning, he or she can safely utilize the instruments to their fullest potential.

Pressure Instruments

Instruments in an airplane can be categorized in several different ways,those are, pressure, gyro, vacuum and radio instruments. After that there is the magnetic compass which works on a different principle. The vertical speed indicator works on the principle of rate of change of differential static pressure.

Static Pressure

By definition, static pressure is the pressure exerted by a column of air of the atmosphere on a unit area.It can also be called the ambient pressure and is always present if the aircraft is moving or is at rest.Static pressure is simply the barometric pressure of the local area. If you fly at any altitude, the atmospheric pressure at that altitude can be called static pressure.Static vents on either side of the fuselage help in the measurement of static pressure.

The reason for two static vents is for redundancy purposes as a static vent might get blocked and in cases of crosswind and side slip maneuvers.In the latter cases, there would be a difference in the measurement of static pressure from the vents and hence to avoid incorrect indications both the vents are connected to each other from the inside to average out the result.

Vertical Speed Indicator

The VSI, which is sometimes called a vertical velocity indicator (VVI), indicates whether the aircraft is climbing, descending, or in level flight. The rate of climb or descent is indicated in feet per minute (fpm). If proper, the VSI indicates zero in level flight.


The VSI display two types of information :

• Trend information shows an immediate indication of an increase or decrease in the aircraft’s rate of climb or descent.
• Rate information shows a stabilized rate of change in altitude.

The VSI indicator in the aircraft uses a logarithmic scale. The reason for using a logarithmic scale is that the lower values have more spacing and the higher values have less spacing. Therefore, it becomes easy to identify even a slight change in the VSI needle from zero position and can be easily recorded.


  • The VSI as we mentioned above works on principle of rate of change of differential static pressure.Before we get to understand how this difference in static pressure is achieved, it is helpful to know the components of a vertical speed indicator.
  • The vertical speed indicator is made up of:
    • CAPSULE:The capsule is connected directly to the static line to receive air of existing atmosphere on one side and through linkages to the VSI pointer from the other side.
    • CASING:The capsule is placed in an airtight casing. The casing also receives static pressure from the static line, however, there is a lag in which it gets its pressure.This helps to create the difference in static pressure which is required for the VSI operation.
    • METERING UNIT/ CHOKE:Metering unit is used to achieve the time delay of static pressure between what is fed to the capsule and the case.The metering unit has a lot of names such as choke, restricted orifice or calibrated leak but the use of it remains the same, that is, to prove the necessary lag to feed the area outside the capsule.
  • When the aircraft is on the ground or in level flight, the pressure inside the capsule and casing is the same and there is no difference in static pressure. This will result in the VSI needle indicating zero.
  • When the aircraft is climbing, the atmospheric (static pressure) reduces as we climb and this is fed to the capsule. The same pressure is fed to the casing through a metering unit that will cause a delay and hence the pressure in the capsule will be less than in the casing which will cause the capsule to compress and indicates a RATE OF CLIMB.
  • When the aircraft is descending, the atmospheric (static pressure) increases as we descend and this is fed to the capsule. The same pressure is fed to the casing through a metering unit that will cause a delay and hence the pressure in the capsule will be more than in the casing which will cause the capsule to expand and indicates a RATE OF DESCEND.


To understand what the VSI needle will indicate in case the static vent gets blocked, I would recommend viewing the diagram used in operations.

  • CASE 1: The aircraft flying level and the static vent is blocked. As flying level, VSI indicates zero and would continue to indicate zero even if the static vent is blocked.
  • CASE 2:During climb, static pressure vent is blocked. Due to the delay in the casing, the Rate of Climb indication will progressively reduce and settle to zero.


  • POSITION ERROR: The position error is on account of the incorrect location of the static vents.Due to this error, the VSI will wrongly indicate a climb or descent when speed is suddenly changed and is most noticeable during take off acceleration.
  • INSTRUMENT ERROR: It is on account of manufacturing imperfections.
  • LAG ERROR: The pointer would take sometime to indicate the change from the time it senses it. This error is most noticeable during prolonged climb or descents at a high rate.
  • MANOEUVRE INDUCED ERROR: Different changes in attitude and configurations of the aircraft will lead to this type of error.This leads to false indications of rate of climb or descent.
  • HYSTERISIS ERROR: When an aircraft is flying at a flight level for a considerable period of time, it will result in the VSI unwilling to respond to changes in static pressure values.

Instrument Check

As part of a preflight check, proper operation of the VSI must be established. Make sure the VSI indicates a near zero reading prior to leaving the ramp area and again just before takeoff. If the VSI indicates anything other than zero, that indication can be referenced as the zero mark. Normally, if the needle is not exactly zero, it is only slightly above or below the zero line. After takeoff, the VSI should trend upward to indicate a positive rate of climb and then, once a stabilized climb is established, a rate of climb can be referenced.

Instantaneous Vertical Speed Indicator (IVSI)

  • To overcome the problem of lag, the Instantaneous Vertical Speed Indicator (IVSI) implements the use of accelerometer (an electromechanical device used to measure acceleration).The IVSI uses a dashpot or a vane type accelerometer.
  • The main advantage of using such an accelerometer is that it responds very quickly to changes in altitude.
  • The sensitivity of a dash pot IVSI is very high and this results in the instrument over reacting in turbulent flying conditions and resulting in false indications and the errors are termed as turning errors. At the time of initiating a level turn, the IVSI momentarily indicates a climbing turn.
picture credit:dutchops

Fact of the Week

Qamdo Bangda Airport, also called Qamdo Bamda Airport, is a plateau airport located in Bangda Prairie, Hengduan Mountains.The Qamdo Bangda Airport started its construction on December 2, 1992. The Air Force only spent 83 days on fixing the 5,500m long and 45 m wide airport runway – the longest one in the world and the airport is 4,334m (14,219 ft) above sea level, which makes it the second highest airport in the world.

 Climate environment of the Qamdo Bangda Airport is quite hostile. Wind speeds up to 30m per second in winter. Besides, the temperature often drops to 20 degrees centigrade below zero in winter and spring, which is difficult for flight operation. Due to its high elevation, the airport oxygen level is only 50% of that of sea level.he airport did a reconstruction and expansion to repaire the runway, building a new terminal of 5,018 square meters. From June 22 to July 15, 2013, the airport was shut down for a further maintenance of the old runway. A second runway is under construction from 2015.

picture credit: Tibet Discovery

We are done for this weeks post. I hope you gained some new knowledge from the world of aviation.If you did, please don’t forget to like this post and share it with your fellow aviation enthusiasts. Until next week, stay safe and stay healthy.



In our early days of flying after going solo and having experienced the joy and responsibility of flying alone, we feel confident about ourselves and build a good relation with our aircraft. The next thing on any aspiring aviators agenda would be to fly for hours and explore new places and aerodromes .Navigation and flight planning are key subjects in aviation because no matter how good we fly the aircraft we yet have to reach our destination and most importantly reach on time.Before the advent of various radio aids that help us in navigation, pilots used to find their way with the help of visual landmarks (pilotage) or dead reckoning.

Dead reckoning is navigation solely by means of calculations based on time, airspeed, distance, and direction.Except for flights over water, dead reckoning is usually used with pilotage for cross-country flying. The heading and ground speed, as calculated from the variables before the flight, are constantly monitored and corrected by pilotage as observed from checkpoints.

Understanding a Few Terms

  • HEADING: Heading is the direction in which the aircraft is pointing. It can also be said that it is the direction in which the fore and aft axis of the aircraft points.It is expressed in three digits and unit is degrees.
  • TRACK: Track is the direction of our aircraft over the ground. The lines we draw on our map before we set out to fly are called tracks.Tracks are also expressed in three digits and unit is degrees.Now , as discussed above in case of no wind condition, the value of track and heading will be the same.
  • WIND DIRECTION: It simply means the direction from which wind is coming.It is expressed in degrees.The wind direction is obtained from the forecast reports and can be provided by the Air Traffic Controller as well.
  • TRUE AIRSPEED (TAS):It is the speed of the aircraft with reference to the surrounding air. The TAS is expressed in knots.
  • GROUND SPEED (GS):The speed of the aircraft in relation to the ground. The ground speed will always be derived from the true air speed . it is expressed in knots as well.As discussed above, in no wind conditions, the TAS and GS will be equal.
  • WIND SPEED:The speed with which the wind flows is provided in knots and given along with the wind direction information.

Effect of Wind

A very important aspect in navigation is the impact wind has on our journey.Wind is a mass of air moving over the surface of the earth.In our day to day life, we observe the effect of wind with the moving trees , dust, balloons and clouds. Wind has a similar effect on aircraft’s movement as well. Most of the navigation in aviation is derived from the navigation of the sea, it is easier to explain the impact of wind on air travel by comparing it to sea travel.

Lets assume that our boat is to leave the shore from place A and is destined for placed B. As the boat departs from place A, the water current is observed to be moving from left to right of the boat and due to this movement, the boat begins to drift to the right with the current. This results in the boat arriving at place C instead of place B.

The same logic applies in aviation but instead of the current , it is the wind that affects us. It is important to note that if the winds are calm, then the aircraft will point where the nose is pointed. In this case, we assume the wind coming from the left side.The aircraft departs from place A and even though it is pointing (heading) towards place B, the aircraft actually travels (track) to place C.

In the above examples, we have considered the wind from the side , that is, crosswind.The wind can be head on (headwind) or from the behind (tailwind) as well. To explain the effect of wind in those scenarios, we consider our aircraft flying north from point A to B with a True Airspeed of 120 Knots.Lets assume our wind is also from the north at a speed on 20 knots, this would result in our Ground Speed to become 100 knots as we have a headwind. On our return leg from place B to A, we are travelling south and our wind direction and speed remains the same. This would result in a tailwind of 20 knots and our resultant Ground Speed would be 140 knots.

What is Drift ?

Now that we know the difference between heading and track, it is understandable that in case of wind, the heading of the aircraft and the track to be followed will vary. The difference in angle between heading and track is known as drift angle.Lets consider our aircraft heading and track are same and track are the same but there is a wind from the left. The wind from the left will cause the aircraft track to push (drift) to the right of the desired track even though we maintain the same heading.

An easy way to recognize if our drift is left or right if to check if the track is to the left or right of our heading.If the track is to the left of the heading, there will be left drift.If the track is to the left of the heading, there will be left drift.


A wind triangle, the pilot’s version of vector analysis, is the basis of dead reckoning.
The wind triangle is a graphic explanation of the effect of wind upon flight. GS, heading, and time for any flight can be determined by using the wind triangle. It can be applied to the simplest kind of cross-country flight, as well as the most complicated instrument flight.The vectors required for constructing the wind triangle are Air vector, Wind Vector and Ground Vector.

  • AIR VECTOR: The Air Vector consists of heading and True Airspeed (TAS) information. The TAS as we have already spoken above is the speed of the aircraft through air (not the indicated speed ). The air vector is drawn with one direction arrow.
  • WIND VECTOR:The Wind Vector consists of wind direction and wind speed.It is important to know that the wind direction is always given in terms of the direction wind is coming from.For example, if the wind direction is 270 degrees, the wind is coming from the west .The Wind Vector is always is also given by three direction arrow.
  • GROUND VECTOR:The Ground Vector consists of track and Ground Speed (GS).The ground vector is drawn by joining the air and wind vector.The vector is drawn with a two direction arrow.


In practice, pilots do not normally draw it out to scale on graph paper, but solve it using an analogue navigation computer. However, the Navigation Computer is merely a device for quickly producing a scale drawing and is actually drawing the Triangle of Velocities for you.It is necessary to consider a practical scale for representing speed as it will be important to draw the triangle on a convenient piece of paper if we are not using the navigation computer.The scale can be of our choice.For example, one inch can represent one knot or one cm can equal one knot.

Lets consider we are flying our aircraft with a TAS of 100 knots and heading north (000 degrees). The wind observed is coming from 240 degrees with a speed of 30 knots.With the help of our wind triangle, find out our track and ground speed ?

STEP 1: On a piece of paper (graph paper, ideally), draw in the Air Vector. It will have a direction of
000 degrees and a vector length equivalent to 100 knots (say, 100 mm).

STEP 2: It is time to draw our wind vector. The wind direction is from 240 degrees.Whatever units you used in proportion to 100 knots TAS (100 mm), draw the length of the wind vector in the same units (30 mm).

STEP 3: The final step is to join the air vector and the wind vector to obtain our ground vector.The ground vector will give us the resultant track and ground speed.

When you do that on your piece of graph paper, if you measure the track with a protractor you
will find that it is 012° and if you measure the length of the ground vector you will find a vector
length equivalent to 118 knots (118 mm).

What this entire problem tells us is that if we fly a heading of a 000 degrees and maintain a TAS of 100 knots, then with the wind mentioned in our example, the resultant path over the ground will actually be a track of 012°T at a ground speed of 118 knots.This is the very basics of flying, navigation and calculating the missing components of the wind triangle.With the advancements in technology and or with the use of the navigation computer you might never draw the wind triangle on a piece of graph paper. Even though you might never use it ,with the help of this technique we can be sure of never getting lost if navigation systems fail in our aircraft.

Here is a practice question for you to have a go at the wind triangle. Our aircraft is on a heading of 053 degrees with a TAS of 132 knots. The wind direction and speed are 205 degrees and 15 knots respectively.Find out the track and ground speed of the aircraft ? Type your answers in the comments down below or if you have any doubts regarding it.


The Hong Kong International Airport opened on July 6, 1998 and is located 30 kilometers northwest of Hong Kong Island. When it first opened its doors to the public, the airport was regarded as having the world’s largest passenger terminal buildings.  According to reports, the 1,255-hectare site area contributed nearly 1% to the total surface area of Hong Kong.

The airport has consistently received awards for its top-notch service, including at least 70 “Best Airport Awards,” according to its website. 

From 2016 to 2019, HKIA was named the “Best Global Airport” by Asia Cargo News. It also received the “Freighter Hub of the Year” award in 2019. 

In 2018, it was named “Airport of the Year” by International Airport Review and “Best Airport in Asia” by Monocle. – Rappler.com

Click the link to know more about Hong Kong International Airport https://www.hongkongairport.com/iwov-resources/file/the-airport/hkia-at-a-glance/facts-figures/HKIA_FactSheet_EN_200518A.PDF

We are done for this weeks post. I hope you gained a few more insights from the world of aviation.I appreciate you giving a few minutes of your day reading this post.Please don’t forget to solve the wind triangle question and drop your answers down below in the comments section.If you liked this post please share it with your fellow aviation lovers. Until next week stay safe and stay healthy.



Hypoxia in aviation is a problem of altitude.It is very important that pilots are alert on how the human body responds to flying at high altitudes when they transition from their light training airplanes to complex high performance aircraft’s that are capable of operating at high altitudes and high speeds.Before we get to know what hypoxia is, we need to understand the relationship of oxygen in our body with altitude.

Oxygen and Altitude

Oxygen is a colourless and odourless gas that makes up 21% of the earths atmosphere by volume. The brain weighs approximately 2% of our body weight but consumes almost 20% of the oxygen that our body needs for its normal functioning.Brain cells die if they don’t receive oxygen for 2 minutes.

Alveoli are tiny sacs in the lungs of a human body where the exchange of oxygen and carbon dioxide takes place through breathing in and out. Therefore it is clear that at anytime the concentration of oxygen should be high and that if carbon dioxide should be low in the alveoli.

According to International Standard Atmosphere (ISA) conditions, the standard pressure at mean sea level is 1013 hectopascal (760 mm Hg). As mentioned above if 21% of the atmosphere is filled with oxygen , it means out of the 760 mm, 160 mm is oxygen. This is what we call partial pressure of oxygen in the air. The human body takes its oxygen from alveoli in the lungs where the partial pressure of oxygen is relatively less (103 mm Hg) as compared to the partial pressure of oxygen in the atmosphere (160 mm Hg).

As we move up to higher altitudes, the amount of partial pressure of oxygen generated by the alveoli also starts reducing. Human beings living at higher altitudes like 10-12 thousand ft above mean sea level, their alveoli produces partial pressure of 55 mm Hg oxygen which is considered to be the minimum for normal operations.

Hence as we go above 10 000 ft, oxygen needs to be added to the cabins air supply .The oxygen that gets added is sufficient to maintain a partial pressure of oxygen that is similar to what humans require on ground (103 mm Hg). A stage is reached where 100% oxygen supply is required to maintain the 103 mm Hg of partial pressure ( what we breathe on the ground)

This stage is at approximately 33,700 feet. However this does not mean that we cannot go above 33, 700 feet, as we discussed above for our normal operations in the body we require a minimum of 55 mm Hg of partial pressure ( what we would breathe at 10 000 feet) . With 100% oxygen supply, this is reached at 40 000 ft .


Hypoxia ( HYPO= less , OXIA=oxygenation) is a condition where not enough oxygen makes it to the cells and tissues in the body. This can happen even though blood flow is normal. Hypoxia can lead to many serious, sometimes life-threatening complications.The most common causes of hypoxia in aviation are: flying, non-pressurized aircraft above 10,000 ft without supplemental oxygen, rapid decompression during flight, pressurization system malfunction, or oxygen system malfunction.

Types of Hypoxia and their Causes:

  • Hypoxic Hypoxia (H) :The reason for this type of hypoxia is the result of low levels of oxygen in the bloodstream. The main reason for this condition occurring in aviation is altitude. As we have discussed in detail above that with increase in altitude, there results a fall in atmospheric pressure and the consequent resultant drop in the partial pressure of oxygen leading to Hypoxic Hypoxia.
  • Anemic Hypoxia (A) :In this type of condition , the lungs are working perfectly but the red blood cells which are the carriers of oxygen in the blood decrease. The reason for the decrease in the count can be due to heavy bleeding, anemia, some type of cancer and lastly the intake of carbon monoxide.
  • Stagnant Hypoxia (S) :In stagnant hypoxia, there is enough oxygen available to breathe but the blood flow is compromised for some reason like a heart attack and the blood is not received by the cells of the body tissues to support their metabolism.Stagnant hypoxia also occurs when the body is exposed to cold temperatures because the blood flow is decreased to the extremities.
  • Histotoxic Hypoxia (H):In this category of hypoxia, there is enough oxygen to breathe and the oxygen is also being carried by the blood but the cells do not accept it. For pilots, some of the primary factors causing hystotoxic hypoxia are alcohol, narcotics and cyanide.

Signs and Symptoms of Hypoxia:

Hypoxia is easy to succumb to the human body and affect each body with varying intensities. even though the condition does not have an alarming warning system to protect us against us the treat, the signs and symptoms are easily recognizable if we identify them. As pilots we need to km=now that no matter the type or cause of hypoxia, the signs and symptoms for each type do not differ a lot and neither do they affect our flying skills in separate ways.

The signs and symptoms are mentioned below:

  • The onset of hypoxia can be accompanied by a feeling of well being, known as euphoria.
  • Impaired Judgement
  • Headache
  • Tingling in hands and feet
  • Hyperventilation
  • Memory and Muscular Impairment
  • Sensory Loss
  • Cyanosis (a bluing of the body extremities)
  • Tunnel Vision
  • Fornication ( a feeling of ants under the skin)
  • Hyperventilation (over breathing)
  • As hypoxia keeps intervening with reasoning, it gives rise to unusual fatigue and finally loss of consciousness or death.

Time of Useful Consciousness (TUC)

This is the period of time from interruption of the oxygen supply, or exposure to an oxygen-poor
environment, to the time when an individual is no longer capable of taking proper corrective and
protective action.It is also know as Effective Performance Time (EPT). We are clear by now that as altitude increases the risk of hypoxia increases and due to that our time for useful consciousness will decrease. Hence, altitude and time for useful consciousness are inversely proportional.The chart below will make it even more clear:

Immediate and Preventive Actions

  • One way to avoid the risk of hypoxia for a pilot to make sure that his aircraft is correctly pressurized above 10,000 feet.
  • In case the aircraft cannot be pressurized, carry supplemental oxygen (don your oxygen mask).
  • If both the above options are not available, it is safe to be flying below 10 ,00 feet and even if we fly above that altitude due weather or terrain, we limit our time to a maximum of 1 hour if flying between 10 to 14,000 feet and 30 minutes if flying between 12 to 14,000 feet.
  • The most important action will always be to use supplemental oxygen above 10,000 feet in day and 5,000 feet at night ( vision gets impaired at a lower altitude in the night due to hypoxia).
  • The most effective way to prevent hypoxia is through education and experience.When pilots are trained in the proper use and care of their pressurization systems and supplemental oxygen equipment, and are aware of their personal hypoxia signs and symptoms, they are safer and better prepared to meet the challenge of flying in an oxygen-poor environment.

Fact of the Week

Boeing’s Everett Site is heralded as having the largest manufacturing building in the world, producing the 747, 767, 777, and the 787 airplanes. Thousands of aerospace employees in Everett support aircraft fabrication and production, product development, aviation safety and security and airplane certifications. Other production areas at the site include the paint hangars, flight line and delivery center. Originally built in 1967 to manufacture the 747, the main assembly building has grown to enclose 472 million cubic feet of space over 98.3 acres.

In January 1967, the first production workers arrived at Everett, and on May 1, 1967, the major assembly buildings opened their doors for the first time. Thousands of people from all over the world visit the Everett site every year. VIP visitors have included U.S. presidents, international dignitaries, CEOs, astronauts and other celebrities.Click the link to know more about this huge airplane manufacturer building https://www.boeing.com/company/about-bca/everett-production-facility.page

We are done for this week. I hope you gained some new insight from this post and if you did please share with it with your fellow aviators and aviation lovers. I encourage you to like this post as it gives me great confidence from your’e interest in these topics. If you have any suggestions please feel free tom drop in a comment or an email, I would be happy to reply. Until next week , stay safe and stay healthy.



Fuel is a material used to produce heat or power by burning. The burning fuel can be used to generate power for lamps, heaters , stoves, lanterns and for running automobile and jet engines. Aviation fuel must meet the strict requirements for flying characteristics and are hence different from the fuel used in automobile engines.

Car Fuel vs Jet Fuel

An internal combustion engine is used to power a car where as a gas turbine engine is needed to power a jet. As mentioned above, they both would require some heat source by burning some sort of fuel to power the engine.

Where car and jet fuel differ is just the number of hydrogen and carbon atoms that are presenting the fuel. For example, car fuel ( gasoline) consists of hydrocarbons that contain anywhere from 7 to 11 carbon atoms with hydrogen molecules attached. Jet fuel, on the other hand, contains hydrocarbons more in the range of 12 to 15 carbon atoms, that is, kerosene.

Therefore, airplane fuel is derived from a much heavier chain of hydrocarbon molecules and the main reason for using it is safety. It takes a higher temperature to ignite kerosene as compared to gasoline. Kerosene is also easily transported and available throughout the world and can stay in the liquid form at lower temperatures which is very important as an airplane flies thousands of feet above the ground.

Understanding a Few Terms

  • Octane Rating/Number: It is a measurement of the quality or performance of the gasoline used. When you go to a gas station to fill petrol , the octane ratings are depicted by regular, mid-grade or premium. The higher the octane rating / number, the better the fuel burns in the engine and hence high performance cars have a need for higher octane ( premium) fuel. Similarly, the gasoline used in airplanes will have a higher octane rating than the gasoline used in cars.
  • Specific Gravity (SG) :Specific gravity also called relative density, ratio of the density of a substance to that of a standard substance.The usual standard substance used for comparing is water . Fuels have specific gravity less than water, which means that they float on water. This helps in identifying the presence of water in fuel during a fuel check .
  • Waxing Point : Waxing point, as the name suggests are the low temperature at which heavy hydrocarbons that are used in making jet fuels as discussed above, turn into wax crystals which clog the fuel filter. This could lead to operation limitations in the fuel system.
  • Flash Point: Flash point is the lowest temperature at which a liquid when exposed to an open flame will turn into vapour. Below the flash point, insufficient vapour is present to support combustion.

Types of Aviation Fuel

Aviation Fuel is divided into 4 categories:

  • Aviation Gasoline (AVGAS)
  • Jet Fuel (JET A and Jet A-1)
  • Kerosene-Gasoline Mixture ( AVTAG OR JET B)
  • Bio Kerosene

Aviation Gasoline (AVGAS)

  • AVGAS is the type of aviation fuel used in small piston engine powered aircraft within the general aviation community. These aircraft are predominantly used by private pilots and flying clubs and for tasks such as flight training and crop dusting.
  • The octane rating of the fuel is specified with the grade , for eg AVGAS 100 is a 100 octane fuel.
  • AVGAS 100 LL and AVGAS 100 are the most commonly used grades of fuel .
  • The AVGAS 100 LL (low lead) and the AVGAS 100 have a lean mixture octane rating of 100 while its rich mixture octane rating is 130 that allows high performance engines to operate safely.
  • The way to differentiate between these two grades of fuel is by their colour . The AVGAS 100LL is BLUE in colour whereas AVGAS 100 is GREEN in colour.A good way to never forget how to differentiate is by noticing that the word Blue and AVGAS 100LL have the letter L.
  • AVGAS 115 was a high-octane avgas mostly used in military combat aircraft in the late 1940s when there was demand for high power output. Now, most military aircraft use turbine engines.

Jet Fuel

  • Gas turbine engine aircraft’s use kerosene fuels.The two types of kerosene fuels used in civilian gas turbine engine aircraft’s are Jet A and Jet A-1.
  • Jet A is a kerosene type of fuel with a specific gravity of 0.8 at 15 degrees C. It has a flash point of 38.7 degrees C and and a freezing point of -40 degrees C.
  • Jet A-1 is similar in comparison to Jet A but has a freezing point of -50 degrees C. It is normally only available in the U.S.A.

AVTAG Fuel (Jet B)

  • AVTAG also called Jet B is a kerosene-gasoline mix type fuel with a nominal specific gravity of 0.77 at 15 degrees C.
  • Jet B can be used as an alternative to Jet A but it has a wider range of flammability as it has a lower flash point and hence is not generally used in civilian aircraft’s .

Bio Kerosene

  • Jet fuel is a type of fossil fuel and eventually will become expensive in the long term.
  • Biokerosene is a mixture of jet fuel and a biofuels which are being used since 2008. There have been approximately 1,50,000 flights that have used Biokerosene to power their aircraft.
  • However these fuels are more expensive than jet fuels and this cost premium is a key barrier to their wider use.


The primary types of contamination are water, particulate and microbiological material. In addition, contamination can occur from other fuel grades and chemicals that may be in multi-product transport systems. The fuel may also be rendered off-specification by either under-dosing/overdosing of approved additives, using an incorrect additive or from product testing issues not limited to, but including, poor sampling, incorrect test procedures and uncalibrated laboratory equipment.


Jet fuels composition allows water to absorbed easily. The degree of water present depends mostly on the temperature of the fuel. When the temperature of the fuel is less, some of the water particles that are already present in the fuel draw out of the solution and accumulate at the lower points of the tank. When the fuel is warmer, it promotes the absorption of moisture from the atmosphere and suspension in the fuel.

Microbiological Growth

Certain bacteria and fungi thrive on the presence of water where it interfaces with jet fuel. The growth of microbial organisms leads to the corrosion of aluminium, steel and rubbers components of the fuel system.


Particulate contamination can occur in a number of different ways. From dirt and sand getting in open ports to degradation of fuel system lines , particulates are constantly being introduced into the fuel system.

Fuel Inspection

During our preflight , if we carry the fuel inspection in a correct manner then the identification of any fuel contamination is not difficult. If a fuel sample appears cloudy of hazy , it could be because of two reasons, the presence of air or water. If the cloudiness appears to be moving towards the top of the sample then air is present , if the cloudiness appears to be moving towards the bottom of the sample then water is present as water has a higher specific gravity than fuel.

Picture Credits: BoldMethod

During fuel sampling ,fuel is drained into a clean and clear container that is filled at least halfway. After collecting the fuel sample, observing it against light helps in identifying water or particulates that could be present. Swirling the sample around by creating a tornado shaped vortex is another way of identification of fuel contamination. The absence of water at the lower points of the tank automatically leads to the elimination of microbial growth. The addition of jet fuel additives can also eliminate the growth of bacteria and other microbes.


A number of additives maybe blended into fuel either at the refinery or the airfield to improve the operational ability of the fuel. The most popular ones are:

  • Fuel System Icing Inhibitors (FSII) : A certain amount of water is present in fuels as discussed above. FSII contains an icing inhibitor and a fungal suppressant to deal with fuel contamination due to water and microbiological fungus that can block fuel system components.
  • HITEC (Lubricity Agent) : A lubricity agent when added to fuel can reduce the wear in fuel system components.
  • Static Dissipater: These additives partially eliminate the hazards of static electricity generated by the movement of fuel through modern high flow fuel transfer systems .
  • Corrosion Inhibitors: The corrosion inhibitors protect ferrous materials in pipelines, storage tanks against corrosion.

Fact of the Week

Concorde was born out of two separate French and British projects which joined forces in 1962. This partnership led to the British Aircraft Corporation (later British Aerospace, and now BAe Systems) and Aerospatiale (now EADS) of France to build a total of 20 Concordes, and became the foundation stone for the formation of Airbus.

Concorde recorded its fastest journey from New York to London on January 1st 1983, taking 2 hours 56 minutes.For most people, flying on Concorde is an impossible dream, the stuff of lottery wins and holidays of a lifetime.For the lucky few, ‘The Bird’ is a convenient method of travel, the equivalent of a bus or a train to the rest of us.Fred Finn was on the first and last Concorde flights and holds the Guinness World Record for the most Concorde flights as a passenger!. Click the link in the link here to know more about this iconic jet https://www.heritageconcorde.com/concorde-information–facts.

Picture Credits: Christian Science

This is to this weeks post. Thank you for reading and hopefully you gained some new knowledge about aviation from this post. If you did , please don’t forget to share it with fellow aviation lovers and don’t forget to comment down below for suggestions. Until next week, stay safe and stay healthy.


Fly-by-Wire ( FBW) Technology

One of the first lessons that student pilots are taught in their training is the relationship between the pitch attitude and power settings required to control the aircraft. Once you get more comfortable and experienced as a pilot, you start your instrument flying journey where you notice how important those initial lessons were on pitch and power as the margin of error is limited and your workload is at it’s peak.

Hence it could be so much easier if there was a system which could control the path of the airplane without the pilot constantly trying to adjust the controls and just obtain the desired pitch attitude and leave the yoke/side-stick without trimming or adjusting the power setting (with the help of the auto thrust – more on this later) . The fly by wire system makes flying much more easier by being that system. It not only controls the path of the aircraft but provides a flight protection envelope as well.

Conventional Flight Control Mechanism

Picture Credits: Slideshare
  • The Wright Brothers used combinations of their body movements to deflect the portions of their FLYER, causing it to move in the desired directions.
  • In a conventional light weight trainer type aircraft , cables are connected to the controls in the cockpit through a bell crank and the other side of the bell crank is connected to the control surface.Movement of the cockpit controls transfers force through the cable to the bell crank, which moves the control surface.
  • However in a high performance aircraft, the control surfaces have great pressure exerted on them and hence it is physically impossible for the pilot to manually move the controls. Hence, hydraulic actuators (cylinders) are placed in the link to assist the pilot in moving the control surface.

Fly-by-Wire System

  • As discussed above, flight controls could be handled mechanically or hydro-mechanically.However, a fly wire system is an electrical way of controlling the flight controls in an aircraft.
  • The fly by wire system adds in an electronic interface to control the aircraft . The pilots command are converted into electronic signals that are interpreted by the flight control computers.The computers interpret the pilot input and determine how to move the actuators connected to the flight control surfaces,as necessary, to follow their orders.
  • The actuators are still hydraulically operated that are similar to the hydro-mechanical system.The computer monitors the aircraft’s response to the flight control movement and modifies its output accordingly to the actuators.

Airbus 320 Fly-by-Wire System

  • In the Airbus 320, there are 7 flight control computers and 3 hydraulic systems to take care of the primary flight controls (elevator, aileron, rudder) .
  • Each primary control has 2 hydraulic actuators, each fed from one of the three independent hydraulic systems.
  • The 7 flight control computers are :
    • There are 2 Elevator and Aileron Computer (ELAC) to control the elevators, ailerons and stabliser.
    • There are 3 Spoiler Elevator Computer (SEC) to control the spoilers ( more on the functioning of spoilers in a separate post) and elevators.In the event of the ELAC failing , the SEC will control the elevators and stabiliser.
    • The rudder is controlled through hydro-mechanical pedals by the pilot, however there are 2 Flight Augmentation Computers (FAC) that operate the rudder to keep the aircraft balanced in a roll.
    • The stabiliser trim can be mechanically controlled by the pilots trim control wheel.
  • To summarise, the elevators and ailerons have access to 5 computers in total and only one is needed for operation.There are 3 hydraulic systems out of which only 1 or 2 are needed for operation, it shows that the system has electrical and hydraulic redundancy built into it .
  • In the event of a total electrical failure, the pilot can control the aircraft manually using the trim wheel for lateral control and rudder pedals for longitudinal control.

Advantages of the Fly-by-Wire System

  • Reduced Weight :Mechanical and hydro-mechanical flight control systems are relatively heavy and require careful routing of flight control cables through the aircraft by systems of pulleys, cranks, tension cables and hydraulic pipes.Hence replacing these with actuators , sensors directly reduces the weight of the aircraft .
  • Flight Envelope Protection: The protection prevents the aircraft from performing manoeuvres outside the flight envelope. For example , stalling or over speeding.
  • Improved Flight Controls: With the help of the fly by wire system, the pilot need not provide excessive control inputs as the computer determines how to move the actuators connected to the flight control surface.
  • Increased Commonality: After the rise of the Airbus 320 family, In terms of Airbus aircraft’s, no matter how one aircraft varies in size or weight from another, fly-by-wire commonality allows the pilot to fly them in the same way because the computer “drives” the aircraft’s flight controls. This leads to considerable reductions in the time and costs involved in training pilots and crew to operate them.
Advantages of the Fly-by-Wire System

Disadvantages of the Fly-by-Wire System

  • Redundancy: The failure of an electrical system could lead to a complete shutdown where as the traditional mechanical flight control system fails gradually and makes the pilot more aware of the failure. The loss of the aircraft flight control computer could immediately make the aircraft uncontrollable.However, in commercial airplanes, this problem is solved by using redundant computers and providing mechanical backup in case of total electrical failure.As seen above, in the working of the Fly-by-Wire system of the Airbus 320.
  • Lack of visual feedback: As the control is not physically connected to the control surface, feedback is lost. The side sticks in the aircraft are not connected to each other that, this means that, the input provided on one side stick cannot be felt on the other and hence visual feedback from the stick is lost.
  • Over dependence on FBW: Murphy’s law states that : “Anything that can go wrong will go wrong ”. Pilots are sometimes guilty on relying heavily on automation. There is no doubt that computers aid pilots in making flying easy but Murphy’s law holds true and there is always a chance for them to fail.

History of the Fly-by -Wire System

  • AVRO CANADA CF-105 ARROW: The Avro Canada CF-105 Arrow (the Arrow) was a supersonic interceptor jet aircraft designed and built in the 1950s by A.V. Roe Canada (Avro). It was fitted with innovative technologies, including a fly-by-wire control system and a computerized control system that allowed the pilot to operate the aircraft electronically. It was canceled on the February 20, 1959 (known as “Black Friday”), a decision that remains controversial today.It was the first non experimental aircraft with fly-by-wire controls.
  • LUNAR LANDING RESEARCH VEHICLE (LLRV) : On May 25, 1961, President John F. Kennedy committed the United States to landing a man on the Moon and returning him safely to the Earth before the end of the decade.In December 1961, NASA Headquarters in Washington, D.C., received an unsolicited proposal from Bell Aerosystems in Buffalo, New York, for a design of a flying simulator to train astronauts on just that challenge.Bell Aerosystems delivered the LLRV-1 on April 8, 1964, where it made history as the first pure fly-by-wire aircraft to fly in Earth’s atmosphere. Its design relied exclusively on an interface with three analog computers to convert the pilot’s movements to signals transmitted by wire and to execute his commands.
  • F-8C CRUSADER: In 1972, NASA gave the world the next big thing in flight controls when the agency’s Dryden Flight Research Center showed how to use the digital fly-by-wire (DFBW) system, the computerized system is used today on everything from jet airliners to cutting-edge fighters and stealth bombers. Dryden’s DFBW aircraft — an F-8C Crusader given to NASA by the U.S. Navy — flew for the first time on May 25, 1972.The program’s chief research pilot, Gary Krier said “Everyone on the program knew that what we were doing was going to be a major breakthrough in flight control”.
  • AIRBUS Fly-by-Wire SYSTEM :One of the A300-600 and A310’s notable innovations had been the introduction of electrical signalling on secondary flight controls, replacing the web of cables and pulleys tradionally used. Airbus wanted to take this evolution further with the next Airbus aircraft – to computer-driven digital “fly-by-wire”, in which the deflections of the flying control surfaces on the wing and tail are no longer driven directly by the pilots’ controls, but by a computer which calculates exactly which control surface deflections are needed to make the aircraft respond as the pilot wishes.
  • DASSAULT FALCON 7X: From its inception, the Falcon 7X was destined to be a revolutionary aircraft, introducing business aviation to the industry’s first Digital Flight Control System.Not only does the 7X handle like a fighter jet, it’s controlled like one. In the cockpit, the pilot’s hand falls naturally on a side-stick controller. Pilots love the 7X intuitive responsiveness and precision. Passengers appreciate its silk-smooth ride and the contribution such an advanced technology makes to aircraft safety.


It was on February 10, 1929 that India got its first licensed pilot in Jehangir R.D. Tata, who qualified with number 1 on his flying license, giving birth to Indian aviation.J.R.D’s license, then called an ‘aviators certificate’, was issued by The Aero Club of India and Burma, an associate of the Royal Aero Club of Great Britain, which was authorised to issue licences by the British Empire’s Federation Aeronautique Internationale. The Aero Club of India and Burma was recognised by Federation Aeronautique Internationale as a sporting authority.

J.R.D. launched India’s first airmail service in 1932, when he flew into Mumbai in a De Havilland Puss Moth from Karachi’s Drigh Road Aerodrome to the Juhu Airstrip via Ahmedabad on the basis of this flying license.This later became the country’s national carrier, Air India.Click the link to know more about iconic figure in aviation history : https://www.tata.com/newsroom/wings-for-a-nation

This is it for this weeks post. I hope you gained some knowledge and if you did, please share it with your fellow aviators . Please feel free to reach out to me via Email, Instagram or Twitter, you’re feedback is always valued. Thank you for you’re support . Until next week , stay and stay healthy.



Aviation makes the world a smaller place and international airlines play a huge role in connecting people from across the globe with different cultures together.International airlines as many international companies all over the world hire people from different countries. For example, Emirates Airlines recruits pilots from all over the world and there are 52 different nationalities of pilots currently in the airline. The top three nationalities being British, Australian and Canadian.

Need for Aviation Language

With such diversity in the crew, the focus on communication is very important. The flight crew, cabin crew , air traffic controller , in short, the entire aviation community need to communicate in a common language. In the history of aviation , a lot of accidents and incidents such as the Tenerife Airport runway collision or the Charkhi-Dadri Mid Air collision have time and again reminded us as aviators the importance of communication.

A)Controller: Descend two four zero zero feet.
In this message, the similarity between “two” and “to” led the pilot to understand 400 feet instead of 2 400 feet. The aircraft crashed into high ground.

B)Pilot: We are at take-off.
In this message, the controller understood that the pilot was waiting in position to begin the take-off, whereas the aircraft had actually begun to accelerate along the runway. It collided in foggy conditions with another aircraft.

The points A and B highlight the ease with which miscommunication can be of serious consequence and impact safety.

What is Aviation Language?

The field covered by the term “aviation language” is relatively broad. It could include all of the language uses of many different professions (engineers, technicians, commercial staff, flight crews, etc.) within the aviation domain.The sole object of ICAO language proficiency requirements is aeronautical radiotelephony communications, a specialized subcategory of aviation language corresponding to a limited portion of the language uses of only two aviation professions — controllers and flight crews.

The language spoken in aviation is called ICAO (International Civil Aviation Organization) English. The ICAO, recommended English to be the language for aeronautical radiotelephony communications in 1951 as most of the English speaking countries dominated the aviation market.English is a first language or a widely used national language in approximately sixty counties and is an important second language in many more.Non-native users of English outnumbered native users at the start of the 21st century by approximately 3 to 1.

Language Proficiency Requirements

Since the 5th of March 2008, every pilot or flight crew member coming into contact with international aviation communication including air traffic controllers must pass a language proficiency exam in compliance with ICAO regulations.

A language proficiency rating scale was developed as a guide to judge pilots and air traffic controllers over their command on the language. The scale was only tests speaking and listening skills and does not address reading and writing skills.

The scale is divided into 6 levels. Levels 1 to 3 on the rating scale assist the examiner on recruiting and training the candidate while Levels 4 to 6 set up a minimum operational requirement. Hence pilots need to need to make sure their language skills meet at least the ICAO Level 4 requirements.If a pilot gets a level 6 rating, he is granted an exemption from the need to be re-evaluated from time to time.

The Language proficiency exam tests consists of pronunciation, structure (use of tense etc), vocabulary, fluency, comprehension and interaction. However to acquire an ICAO Level 4 rating does not require high degrees of grammatical correctness and traditional English language .

Level 1,2 and 3 on the Rating Scale
Level 4 ,5 and 6 on the Rating Scale

ICAO Phonetic Alphabet

The International Civil Aviation Organization created the international radiotelephony alphabet, tied to the , English Alphabets . They were created to avoid the confusion between similar sounding alphabets such as B and D or M and N. Therefore on the radio the ATC will instruct the pilots the to “ Hold short of holding point APLHA” and not “Hold short of holding point A” .


The foundation’s of standard phraseology were laid in the Annex 10 Volume 2 of the ICAO Annexure. Standard phrases are of extremely useful in emergencies and unusual situation and helps keep communication concise.Therefore learning the new aviation alphabets is not the only difference in the aviation language, pilots and ATCs need to have these standard words and phrases registered in their memory.

There are about 300 standard words and phrases that are used. Some of the most common ones are listed below along with their meaning:

  • Acknowledge: Let me know when you have received and understood the message
  • Affirm: Yes
  • Approved: Permission for proposed message granted
  • Break: I hereby indicate the separation between portions of the message (to be used where there is no clear distinction between the text and other portions of the message)
  • Break Break: I hereby indicate separation between messages transmitted to different aircraft in a very busy environment
  • Cancel: Annul the previously transmitted clearance
  • Check: Used to examine a procedure or system
  • Cleared:Authorised to proceed under specific conditions
  • Confirm:Have you correctly received the message ?
  • Contact : Establish radio communication with …
  • Correction: An error has been made in the previous transmitted message. The corrected message is …
  • Disregard: Consider the transmission as not sent
  • I say again: Repeating for clarity of the message
  • Maintain: Continue in accordance with the condition specified . for eg, ‘Maintain VFR’ (VFR- Visual Flight Rules)
  • Mayday: My aircraft and its occupants are threatened by grave and imminent danger and/or I require immediate assistance
  • Negative: Permission not granted
  • Over: My transmission has ended and I expect a response
  • Pan Pan: I have an urgent message to transmit concerning the safety of my aircraft, or other vehicle or of some person on board, or within sight, but I do not require immediate assistance
  • Read Back: Repeat all, or the specified part, of this message back to me exactly as received
  • Report: Pass me the following information
  • Request: I wish to obtain
  • Stand by : Wait , I will connect with you in a bit
  • Wilco: I have understood your message and will comply with it

FACT OF THE WEEK: Mason Andrews, age 18 Yrs 163 Days became the youngest person to circumnavigate the globe in an aircraft when he completed his journey in Monroe, Louisiana, USA on the 6th of October 2018. Mason flew a single engine Piper PA -32 around the world in 76 days.

Andrews’s journey was only made possible by initially telling his parents he was flying solo across the Atlantic and no further. His parents were resistant to even allow this trip, but they were eventually persuaded by the scale and detail of his preparations. It was only later that they learned of the worldwide trip he was planning.

This is it for this weeks post. I hope you gained some new knowledge from it. Please share it with your fellow aviators and enthusiasts if you liked this post. Feel free to comment for suggestions. Until next week , stay safe and stay healthy .



The development of electronic communications over a period of time has been a big advantage for the aviation industry.The Airbus believes in Fly , Navigate and Communicate . With the help of electronic communication, the emphasis on verbal communication between the pilots and the air traffic controller has reduced severely .This helps aviators to concentrate on flying the aircraft which is of utmost importance.

Transponders and squawk codes help in reducing verbal communication and help maintain a silent cockpit.They assist the air traffic controller in knowing the aircraft position on their radars.



A transponder (XPDR) as the name suggest is a transmitter and receiver. It is an electronic device that produces a response to an interrogation signal sent by the air traffic controller.

It was initially used in the military to identify aircraft’s . It was termed as ‘Identification of Friend or Foe’ as a military aircraft sent interrogation signals to another aircraft to find out if they are their friends or foes .

However , in commercial operations, as we only have friends we do not use these terms . The Air traffic controller assigns each aircraft a squawk code which enable them to identify the aircraft on their radar and other aircraft’s collision avoidance system.

Conventional Transponder


The ground based equipment transmits interrogation pulse signals on a frequency of 1030 MHz (Megahertz) and receives on 1090 MHz.While the Aircraft transponder , transmits on 1090 MHz and receives on 1030 MHz .

Signals from the ground transmitter are transmitted in pair of pulses that are coded and each code is known as a MODE.There are a few modes that will be discussed down below. The replies from the aircraft are however in all directions.

The ground receiver then decodes the reply from the aircraft and displays the necessary information such as aircraft call sign, altitude , speed etc on the radar.


The different modes of transponder help us gain different information of the aircraft .

  • MODE A:This type of transponder provides an identification code only .
  • MODE C: In Mode C, along with identification code , aircraft pressure altitude is provided as well .
  • MODE S: In Mode S (selective) ,there are a number of details that can be provided along with aircraft identification code and altitude. For example, aircraft ground speed , destination of the aircraft , desired track etc.

A Mode C transponder is commonly found in general aviation aircraft’s where as the commercial jets are equipped with Mode S transponder. In the flight plan that is needed to be file before a flight , it is necessary to mention the type of surveillance equipment (transponder) installed on board. In the ICAO flight plan, the necessary details are included in box 10,that is , Equipment ( more on flight plan in a separate post).



Once the ground receiver has decoded the information, the radar displays the necessary information depending upon the mode of transponder. The different aircraft’s are shown as a blip or a trace on the radar screen.In the figure down below , the example shows the aircraft is equipped with a MODE S transponder.



A-320 Transponder

STBY: The Stand By function powers up the transponder and makes it available for operation.

ON : In the ON position, it will send primary information to the radar, that is , it will work like a MODE A transponder.

ALT:If the ALT RPTG is in the ON position , the transponder will send altitude data and will work like a MODE C/ MODE S transponder.

IDENT: All modes (A,C,S) include an ident button.It reveals the identity of the aircraft to the ATC on their radar and helps them locate the aircraft too. For example, when the ATC requests the aircraft to ‘SQUAWK IDENT’ , the pilots need to press the ident button which leads to the aircraft blip on the radar to flash and enables the controller to easily identify the aircraft among many other that are near it.


What are Squawk Codes?

Transponder transmission usually requires a discrete code to identify the aircraft. These codes are assigned by the ATC to each aircraft in their departure clearance.

The squawk codes are 4 digit octal numbers from 0 to 7 and range from 0000 to 7777. Once the pilot receives his squawk code , he has to enter the 4 digit code so that he is visible on the radar .

Let’s take an example, the controller on your departure clearance assigns the pilot to squawk 1234. The pilot can enter 1234 via the numbers shown in the image below and the screen will display the squawk code entered.

Reserved Codes

There are a few transponder codes that have a predetermined meaning and should be used when the aircraft faces that occurrence.

In the above mentioned reserved codes, it is always a good idea to remember the last three codes as they notify the ATC immediately of the problem. As a good rule of thumb, I remember the word ice, that is, interference communication emergency and corresponding to those are the codes, which are, 7500 7600 7700.

Check the image on the right to have a better understanding.

FACT OF THE WEEK: This week we go back to the years where the Wright Brothers were busy making their first powered airplane . A powered airplane would require an engine for the aircraft to take flight. Charles “Charlie” Taylor a mechanic who worked at the Wright Brothers bicycle shop stepped up to help them in their pursuit and became the first man to build an engine that powered an airplane and the first aviation mechanic in history. If it hadn’t been for Charlie the first powered airplane would never have gotten off the ground.

Please click on the link to know more about Charlie Taylor https://www.faa.gov/about/office_org/field_offices/fsdo/phl/local_more/media/ct%20hist.pdf

We are done for this week. I hope you gained some knowledge from this post and if you did please like and share it with your fellow aviators.Please feel free to comment if you have any doubts or suggestions for further posts. Until then stay safe, stay healthy.



“CLEARED FOR TAKE OFF”- when a pilot hears these words from the Air Traffic Controller, he knows it is time for him to bring the highest order of focus he can for one of the most critical phases of flight , that is ,take off.

Need for Take off Segments

One of the significant emergencies that an aircraft can face is an engine failure on take off , it means that the engine is no longer providing the necessary thrust needed.In order for the aircraft to be safe from any emergencies that may occur , it is necessary that it achieves the minimum climb gradients and clears its surrounding area and obstacles with sufficient altitude. Hence the take off segments help in achieving the above requirements.

Understanding a few terms

Before we look at the different segments of climb, it is necessary to understand a few terms related to the take off segments as it will help us understand the post better.

SCREEN HEIGHT:The take off part of the flight is the distance from where the brakes are released to the point at which the aircraft reaches a defined height.This defined height is known as screen height.It is usually 35 ft (for class A aircraft) on a dry runway and if the runway is wet it can reduce down to 15 ft.

TAKE OFF SAFETY SPEED (V2): V2 is the target speed the aircraft should attain prior to or before reaching the screen height. The reason it is called take off safety speed is because it should be attained with one engine inoperative and avoid the aircraft from stalling or the pilots loosing control of the aircraft.


CLIMB GRADIENT:The ratio of change in height (altitude gained), during a portion of a climb, to the horizontal distance traversed in the same time period.It is expressed as a percentage. It also refers to the angle at which the aircraft climbs.For an aircraft to climb , thrust has to balance drag and a part of the weight as well . Hence we require excess thrust to give us the climb gradient or angle of climb .

Climb gradient =Excess Thrust *100/Weight

The take off climb segments start from the screen height that is 35 ft above the take off surface and end at 1500 ft above the take off surface and are divided into 4 segments.

Segment 1

  • The first segment starts when the aircraft reaches the screen height, that is 35 ft .
  • The aircraft keeps climbing at the take off safety speed, that is V2 speed, until the gear is retracted.
  • The objective of this segment is to expedite the climb and to make sure there is reduction in drag .
  • There are two ways to reduce drag in this scenario , retracting the flaps or the landing gear.
  • Since retracting the flaps very close to the ground is dangerous, we choose the option of retracting the gear .
  • The first segment ends as soon as the landing gear is retracted .

Segment 2

  • The second segment commences from the gear retraction point and the aircraft still has to maintain the take off safety speed (V2).
  • The next important step is to retract flaps so that we can start accelerating the aircraft .
  • However , companies have a set altitude from which the flap retraction can start for example , 400 ft AAL (above aerodrome level).
  • As the gear is already retracted in the previous segment, the main source of drag is removed.
  • This makes it easier for the aircraft to climb at a higher climb gradient than segment 1. The climb gradient should not be less than 2.4%.
  • The main objective of the second segment is to clear the aircraft from the surrounding obstacles by maintaining the necessary climb gradient .
  • The second segment concludes at 400 ft AGL or the height decided by the company from where flap retraction can commence .

Segment 3

  • The third segment begins from 400 ft or flap retraction altitude set by the company .
  • The main objective of this segment is to accelerate the aircraft so that the flaps can be retracted step by step .
  • The reason we accelerate while retracting the flaps is because the stall speed will increase when we retract flaps .
  • Hence as the aircraft accelerates from take off safety speed (V2) to a higher speed that is minimum drag speed or best angle of climb speed so that the aircraft doesn’t get close to stall speed .
  • Once the flaps are retracted , we can set the thrust levers to maximum continuous thrust (MCT) from take off thrust .
  • In the Airbus 320, take off thrust can only be used continuously for a period of 05 mins on both engines and in case of an engine failure , it can be used continuously for 10 mins.
  • The segment however ends once the thrust lever are set to MCT and flaps are retracted .

Segment 4

  • The fourth segment starts once the trust levers are set to MCT and flaps are retracted.
  • The climb gradient for the last stage should not be less that 1.2%.
  • In the fourth segment, the airplane is climbed to above 1500 ft AAL (above aerodrome level) where the take off flight path ends.
  • In case of an engine failure , the pilot can make a decision to land at the departure aerodrome or go on further to an alternate airfield.

FACT FOR THE WEEK: This week we talk about the worlds largest passenger carrier aircraft , the Airbus A380. It is a double decker behemoth with four engines and has a cabin that can be occupied by more than 500 people .It first took flight in 2005 and was first delivered to Singapore Airlines in 2007.The Airbus A380 is also sometimes referred to as the SuperJumbo.

In 2019, it was however announced by Airbus that it would stop the production of the aircraft and the ones already in production will be delivered by 2021.The reason behind this was majority of the airlines preferring the new Airbus A350 in comparison to the A380 . The SuperJumbo will be definitely missed.

This is it for this weeks post. I hope you had a good read and got to learn something new as well . If you did , please don’t forget to likely share it with fellow aviators and aviation enthusiasts. Please feel free to comment for any questions or recommendations on the blog or further topics .Until next week , stay safe and stay healthy .