Need for Airport Marking
Imagine yourself piloting your favorite aircraft out of Chicago O’Hare International Airport on a very busy afternoon for the first time and you’ve just received your taxi clearance, as you start to taxi there are no clear airport markings to guide you to the runway.If I was in your seat, I would be the most confused person at that airport.
A lot of things in Aviation require uniformity and standardization just like we discussed in Freedoms Of The Air.Hence, Airport Markings help enhance safety which is of prime importance and aids pilots avoid confusion during critical stages of flight that are taxi, take off and landing.
Types of Airport Markings
Airport markings are categorized mainly into :
- Runway Markings
- Taxiway Markings
- Hold Position Markings
- Other Markings
- Mandatory Instruction Marking
- Information Marking
1.RUNWAY DESIGNATION MARKINGS
- A runway designation marking shall be provided at the thresholds of a paved runway. However it is also recommended on unpaved runways (grass, dirt, sand runways).
- A runway designation marking shall consist of a two-digit number and on parallel runways shall be supplemented with a letter.
- For example, Runway 21 and in case of parallel runway runway 21 L or 21 R.
- On a single runway, dual parallel runways and triple parallel runways the two-digit number shall be the whole number nearest the one-tenth of the magnetic North when viewed from the direction of approach.
- If The actual direction of the runway could be 206 degrees however we round it to the nearest one tenth whole number that is 210 degrees and hence runway 21.
- If The actual direction of the runway could be 202 degrees however we round it to the nearest one tenth whole number that is 210 degrees and hence runway 20.
- On four or more parallel runways, one set of adjacent runways shall be numbered to the nearest one-tenth magnetic azimuth and the other set of adjacent runways numbered to the next nearest one-tenth of the magnetic azimuth.
- For example, if we have four parallel runways of direction 202, 204, 206, 208 degrees we name one set of them as 20 R and 20 L and the other set as 21 R and 21 L.
- When the above rule would give a single digit number, it shall be preceded by a zero.
- This simply means that we do not write 8 L and 8 R for runway designation instead it is designated as 08 L and 08 R.
- In the case of parallel runways, each runway designation number shall be supplemented by a letter as follows, in the order shown from left to right when viewed from the direction of approach:
- — for two parallel runways: “L” “R”;
- — for three parallel runways: “L” “C” “R”;
- — for four parallel runways: “L” “R” “L” “R”;
- — for five parallel runways: “L” “C” “R” “L” “R” or “L” “R” “L” “C” “R”; and
- — for six parallel runways: “L” “C” “R” “L” “C” “R”.
RUNWAY CENTRE LINE MARKINGS
- A runway centre line marking shall be located along the centre line of the runway between the runway designation markings.
- However at the intersection of two or more runways , priority is given to the more important runway markings except for the runway side strip markings.
- A runway centre line marking shall consist of a line of uniformly spaced stripes and gaps. The length of a stripe plus a gap shall be not less than 50 m or more than 75 m. The length of each stripe shall be at least equal to the length of the gap or 30 m, whichever is greater.
- For example, the centre line marking can be 30 m long with a gap of 20 m between the next marking which makes it a total of 50 m however this total cannot exceed 75 m.
- A threshold marking shall be provided at the threshold of a paved instrument runway and also on a paved non instrument runway with code number 3 or 4 and the runway is intended for use by international commercial air transport.
- The stripes of the threshold marking shall commence 6 m from the threshold.
- A runway threshold marking shall consist of a pattern of longitudinal stripes of uniform dimensions disposed symmetrically about the centre line of a runway.
- The number of stripes in a threshold marking depends on the width of the runway.
AS A GOOD RULE OF THUMB, I ONLY REMEMBER 12 STRIPES CORRESPONDING TO 45 M AS MOST INTERNATIONAL AIRPORTS HAVE THAT. THEN IF YOU DIVIDE IT BY 2 YOU GET 23 M AND 6 STRIPES. SIMILARLY, IF YOU REMEMBER 60 M WITH 16 STRIPES AND YOU DIVIDE THAT BY 2 YOU GET 30 M WITH 8 STRIPES.
TRANSVERSE STRIPE AND ARROWS
- Where a threshold is displaced from the extremity of a runway or where the extremity of a runway is not square with the runway centre line, a transverse stripe should be added to the the threshold.
- A displaced threshold is a runway threshold located at a point other than the physical beginning or end of the runway.
- A displaced threshold occurs due to runway repairs, obstructions and this results in the displaced part not being used for landing.
- A transverse stripe should be 1.80 M or more wide in length.
- Where a runway threshold is permanently displaced, arrows conforming shall be provided on the portion of the runway before the displaced threshold.
- When a runway threshold is temporarily displaced from the normal position, it shall be marked as shown in the figure below and all markings prior to the displaced threshold shall be obscured (make something difficult to observe) except the runway centre line marking, which shall be converted to arrows.
TOUCHDOWN ZONE MARKINGS
- A touchdown zone marking shall be provided in the touchdown zone of a paved precision approach runway.
- A touchdown zone marking shall consist of pairs of rectangular markings symmetrical from the runway centre line with the number of such pairs related to the landing distance available.
- The pair of touchdown zone markings shall be spaced at a distance of 150 M beginning from the threshold.
AS A GOOD RULE OF THUMB, I JUST REMEMBER THE FIRST VALUES.FOR EXAMPLE, 900, 1200, 1500 AND 2400 M AND THEIR CORRESPONDING PAIR OF MARKINGS.
RUNWAY SIDE STRIPES
- A runway side stripe marking shall be provided between the thresholds of a paved runway where there is a lack of contrast between the runway edges and the shoulders or the surrounding terrain.
- The runway side stripes help in providing a visual contrast between runway edges and the abutting terrain which sometimes could be tough to differentiate.
- The stripes are continuous white located on each side of the runway.
TAXIWAY CENTRE LINE MARKINGS
- Taxiway centre line marking shall be provided on a paved taxiway, de-icing/anti-icing facility and apron so as to provide guidance between the runway centre line and where the aircraft stands.
- Taxiway centre line marking shall be at least 15 cm in width and a single continuous yellow line except where it intersects with a runway-holding position marking or an intermediate holding position marking.
- It should be noted that although the taxiway centre line markings keep the aircraft along the centre they do no provide wing tip clearance.
ENHANCED TAXIWAY CENTRE LINE MARKINGS
- Enhanced Taxiway Centre Line Markings should be provided to denote the proximity of runway holding position.
- They should also be installed at runway/ taxiway intersections if possible.
- If provided they shall extend from the runway hold position to a distance of up to 47 M in the direction of travel away from the runway.
Hold Position Markings
RUNWAY HOLD POSITION MARKINGS
- The hold position markings on the taxiway are indications for the aircraft to stop before entering the runway .
- Air Traffic Clearance is required for aircraft’s to enter the runway however while exiting the runway to a taxiway, air traffic clearance is not needed unless stated by the controller.
- The hold position markings consist of 4 yellow lines, that is , 2 solid and 2 dashed and 3 spaces at 0.15 M each.
INTERMEDIATE HOLD POSITION MARKINGS
- Intermediate hold position markings are used at an intersection of two taxiways.
- It shall be located across the taxiway at sufficient distance from the near edge of the intersecting taxiway to ensure safe clearance between taxiing aircraft.
- An intermediate holding position marking shall consist of a single broken line.
- When instructed by ATC to hold at a particular taxiway, the aircraft must stop and not cross the intermediate hold position marking until advised by ATC.
INSTRUMENT LANDING SYSTEM HOLD POSITION MARKING
- The ILS (more on the instrument landing system in a separate post) hold position marking consist of two yellow solid lines spaced two feet apart connected by pairs of solid lines spaced ten feet apart extending across the width of the taxiway as shown below.
- A sign with an inscription in white on a red background is located adjacent to these hold position markings.
VOR AERODROME CHECKPOINT MARKING
- A VOR aerodrome checkpoint marking shall be centred on the spot at which an aircraft is to be parked to receive the correct VOR signal.
- A VOR aerodrome checkpoint marking shall consist of a circle 6 m in diameter and have a line width of 15 cm as shown below.
- These markings should be preferably white in color with a black border to provide contrast and necessary to be different from the taxiway color markings.
AIRCRAFT STAND MARKINGS
- Aircraft stand markings should be provided for designated parking positions on a paved apron and on a deicing/ anti icing facility.
- These markings should include information like stand identification, lead in line, turning line, stop line and lead out line.
- The lead in line should include stand identification information (number and/or alphabet) that is visible for the reader from the cockpit.
- When two sets of aircraft stand markings are superimposed on each other then to make it understandable for the pilot the aircraft identification should also be added with the markings.
- For example, 2a-A320 AND 2b-B737.
APRON SAFETY LINES
- Apron safety lines should be provided on a paved apron as required by parking configurations and ground facilities.
- These markings define the areas to be used by ground vehicles and other aircraft servicing equipment and provide safe separation from aircraft’s such as wing tip clearance.
- The apron safety lines should continuous in length and 10 CM in width.
ROAD HOLDING POSITION MARKING
- A road holding position marking should be provided at all road entrances to a runway.
- These markings shall be in accordance with local road traffic regulations.
Mandatory Instruction Marking
- Mandatory Instruction Marking assist in prevention of runway incursions. A mandatory sign should be installed and in places where it is impracticable to install signs , mandatory markings are used.
- The markings on taxiways shall be equally located along the taxiway centre line and holding side of the runway holding position marking.
- The marking should consist of an inscription in white on a red background.
- For example, “No ENTRY” written in white on red background for a no entry marking.
- Information Markings are helpful when there are complex taxiway intersections and when information signs are not available.
- An information marking shall consist of :
- An inscription in yellow upon a black background, where it replaces or supplements a location sign.
- An inscription in black upon a yellow background, where it replaces or supplements a direction or destination sign.
FACT FOR THE WEEK: Beijing Daxing International Airport (PKX) is the largest international airport in the world.With its opening in September 2019, it spans over 7.5 million square feet and took over 11 billion dollars to build it.Based on the starfish theme, it ensures convenience and eco friendliness.It takes about a total of 8 minutes for passengers to travel from security to their gate. The first phase of the airport project is designed with a target of 72 million passengers, 2 million tons of cargo and mail and 620,000 aircraft movements in the long term.
This is it for this weeks post. I hope you liked it and learnt something new from it. Please don”t forget to share it with your fellow aviators.Until next week, stay safe and stay healthy.