PPL(A) Theory

Aerodromes: definitions and aerodrome data

Page ID
010-09-01
Syllabus (AMC1 FCL.210; FCL.215)
Definitions; Aerodrome data: conditions of the movement area and related facilities
Syllabus anchor
ICAO Annex 14
Rule in force
Reg. (EU) No 139/2014 (aerodromes) and CS ADR-DSN
Regulatory baseline
Regulation (EU) No 139/2014 (aerodromes) with CS ADR-DSN, Easy Access Rules for Aerodromes (March 2026)
Reading time
26 min
Revising? Key concepts ↓ Test yourself ↓

Learning objectives

The idea

A runway is more than a strip of tarmac. Around it and beyond it are areas that exist only to catch mistakes: an aeroplane that runs off the side, stops short or goes too far. Some of that space is safe to climb over, some to stop on, none to land on. The aerodrome must also tell you how much runway is on offer, what state the surface is in, and what has changed. This page gives you the words and numbers to read that information and compare it with what your aeroplane needs.

Who the EU aerodrome rules cover

The EU aerodrome rules apply to aerodromes in the EU that are open to public use, serve commercial air transport and have a paved instrument runway of 800 m or more. All three conditions apply together.

Many small PPL(A) airfields do not meet them. They are regulated nationally, so their layout and data need not follow the EU design specifications. Read what the aerodrome publishes.

Rule Reg. (EU) 2018/1139 Art. 2(1)(e), Art. 2(7)

The EU aerodrome rules cover aerodromes inside the scope of the Basic Regulation. A Member State may exempt an aerodrome with no more than 10 000 commercial air transport passengers and no more than 850 cargo-related movements a year, which is then regulated nationally.

Elevation, reference point and reference temperature

What an aerodrome, the movement area and a runway are is taught on the rules of the air definitions page (010-05-01). The extra terms here are these.

The landing area is the part of the movement area intended for landing or take-off. The aerodrome elevation is the elevation of the highest point of the landing area. It is not an average.

The aerodrome reference point is the designated geographical location of the aerodrome, near its geometric centre. The aerodrome reference temperature, in °C, is the mean of the daily maximum temperatures in the hottest month, averaged over five years.

Thresholds and runway numbers

The threshold is the beginning of the part of the runway usable for landing. The touchdown zone is the part beyond it where landing aeroplanes are intended to touch down first. A displaced threshold is a threshold that is not at the end of the runway. The displacement can be permanent or temporary.

Why displace it? Permanently, when an object such as a tree line pokes through the approach path and cannot be removed; temporarily, when part of the runway is unserviceable. The price is less runway to land on. Markings are taught on page 010-09-03.

The runway number is the whole number nearest to one-tenth of the runway's magnetic bearing as seen from the approach direction, written with two digits. Parallel runways add L and R, or L, C and R, left to right as you approach. So the two ends of one runway differ by 18 in their numbers.

The safety areas: strip, graded area and RESA

The runway strip is a margin around the runway: a defined area that includes the runway and any stopway, reducing the risk of damage to an aircraft that runs off and protecting aircraft flying over it. Inside it, the graded area is cleared of obstacles and graded to limit damage.

For code number 2, 3 or 4 (explained below), the strip reaches at least 60 m before the threshold and beyond the runway or stopway end. Beyond the strip end comes the runway end safety area, RESA: a symmetrical area on the extended centre line, mainly to reduce damage when an aeroplane undershoots or overruns. It is provided at each strip end for code number 3 or 4 and for code 1 or 2 instrument runways, and for small non-instrument runways where practicable. Its minimum length is 90 m from the strip end, and 240 m as far as practicable for code 3 or 4. Its width is at least twice the runway width. A runway used in both directions has two RESAs.

Runway strip and runway end safety area, plan view Plan view for a code 3 or 4 runway: runway and centre line inside a strip that reaches 60 m beyond each end, then a hatched RESA 90 m long and twice the runway width, continued by a dashed outline to 240 m. Not to scale. Plan view, code 3 or 4 · not to scale Runway Centre line Runway strip 60 m 60 m 90 m min. 240 m where practicable 90 m min. 240 m where practicable twice the runway width Hatched: RESA, at least 90 m long Dashed: RESA out to 240 m, if practicable Strip and RESA are not runway: they count in no declared distance.
Figure 1. The strip surrounds the runway and reaches 60 m beyond each end. Beyond the strip, the RESA is at least 90 m long and twice the runway width, and 240 m where practicable. Not to scale. Original diagram
Describe this figure

A plan view of a runway for code number 3 or 4, with the runway and its dashed centre line in the middle of a wider strip box. The strip reaches 60 m beyond each runway end, shown by dimension arrows. Beyond each strip end a hatched box marks the runway end safety area, at least 90 m long and symmetrical about the extended centre line. A dashed outline continues each hatched box out to 240 m, labelled where practicable, and a dimension arrow shows that the width is twice the runway width. A note says the strip and the RESA are not runway and count in no declared distance.

The figure is a plan view: the runway and its centre line, a wider strip box reaching 60 m beyond each runway end, then beyond each strip end a hatched box 90 m long and twice the runway width, the minimum RESA, continued by a dashed outline out to 240 m where practicable. Strip and RESA are not runway and count in no declared distance.

Clearway and stopway

The clearway answers: where can I climb? It is a defined rectangular area on the ground or water, under the control of the aerodrome, over which an aeroplane may make part of its initial climb to a specified height. When provided, it starts at the end of the take-off run available, is no longer than half of that run, and extends at least 75 m each side of the extended centre line. Objects that could endanger aeroplanes in the air are removed.

The stopway answers: where can I stop? It is a defined rectangular area at the end of the take-off run available, prepared so an aircraft can be stopped there after an abandoned take-off. When provided it is as wide as the runway and strong enough for the aeroplane it serves.

A clearway is to fly over, a stopway to roll on. Neither is for landing.

Declared distances

The aerodrome publishes four lengths for each runway direction.

With no stopway, no clearway and the threshold at the runway end, all four equal the runway length. A clearway adds to TODA only. A stopway adds to ASDA only. A displaced threshold reduces the LDA by the displacement, only for landings towards that threshold. The opposite direction is unaffected.

TODA and ASDA are each at least TORA, neither has to be larger than the other, and nothing adds to LDA.

Building the declared distances in five steps Five plan-view panels of one runway, operating left to right: plain runway, with clearway, with stopway, with displaced threshold, and all combined, each with arrows for TORA, TODA, ASDA and LDA. Take-off and landing run left to right → A Plain runway All four distances equal the runway length Runway TORA · TODA · ASDA · LDA B Clearway added The clearway adds to TODA only CWY Runway TORA · ASDA · LDA TODA C Stopway added The stopway adds to ASDA only SWY Runway TORA · TODA · LDA ASDA D Displaced threshold The displacement cuts LDA only Runway LDA TORA · TODA · ASDA E All combined Each distance follows its own rule CWY SWY Runway LDA TORA ASDA TODA
Figure 2. Operations run left to right. A clearway adds to TODA only, a stopway to ASDA only, and a displaced threshold cuts LDA only. Lengths are invented and not to scale. Original diagram
Describe this figure

Five plan-view panels of one runway, operations running left to right. In A, a plain runway, one arrow labelled TORA, TODA, ASDA and LDA spans the whole runway. In B, a clearway box beyond the far end is wider than the runway, and only the TODA arrow reaches its end. In C, a stopway box as wide as the runway follows the far end, and only the ASDA arrow reaches its end. In D, two arrowheads on the centre line precede a group of threshold bars, and the LDA arrow starts at the threshold while the other three start at the runway extremity. In E, everything is combined: LDA runs from the displaced threshold to the runway end, TORA to the runway end, ASDA to the end of the stopway and TODA to the end of the clearway.

The figure builds the distances in five steps. A: a plain runway, one arrow for all four distances. B: a clearway box beyond the far end; only the TODA arrow reaches it. C: a stopway box as wide as the runway; only the ASDA arrow reaches it. D: a displaced threshold; the LDA arrow starts at the threshold. E: all combined.

If you enter the runway from a taxiway part-way along, the reduced take-off distances are measured from a datum line straight across the runway, where the downwind edge of the entry taxiway meets the runway edge. The runway behind that line is not counted.

Datum line for an intersection take-off Two plan views of a runway with an entry taxiway, right-angle and angled, each with a dotted datum line across the runway where the rear edge of the taxiway meets it. Runway behind the line is not counted. Right-angle entry Datum line Not counted Reduced distances measured from here Entry taxiway, right angle Angled entry Datum line Not counted Reduced distances measured from here Entry taxiway, angled
Figure 3. For an intersection take-off, the reduced distances are measured from a datum line across the runway at the rear edge of the entry taxiway. The runway behind the line is not counted. Original diagram
Describe this figure

Two plan views show a runway running left to right with an entry taxiway joining from below. In the first, the taxiway meets the runway at a right angle; in the second, at an acute angle. In each, a dotted datum line is drawn straight across the runway at the point where the taxiway edge on the take-off-start side meets the runway edge. A dimension arrow to the left of the line is labelled not counted, and one to the right says the reduced distances are measured from the line. An aeroplane on the taxiway turns onto the runway towards the right.

The figure shows an angled and a right-angle entry, each with a dotted datum line.

Aircraft-specific

The distances your aeroplane needs, and the corrections for grass, wet or contaminated surfaces, come from the POH/AFM, not from aerodrome data. Check your aircraft's POH/AFM. This lesson does not replace ATO instruction or the aircraft's POH/AFM.

Good practice

Before using a runway, compare the declared distances for your direction, and the current runway condition, with the POH/AFM distances including surface corrections.

The aerodrome reference code

The aerodrome reference code, ARC, is a code number plus a code letter. The number comes from the longest aeroplane reference field length of the aeroplanes the runway is meant for: 1 is below 800 m, 2 is 800 m to below 1 200 m, 3 is 1 200 m to below 1 800 m, 4 is 1 800 m or more. The letter comes from the greatest wingspan, A (below 15 m) to F. It is a planning tool for design specifications such as strip and RESA. It does not set runway length or pavement strength, and does not limit which aircraft may operate.

Aerodrome reference code: the number comes from the length band, the letter from the wingspan, A smallest to F largest (< means less than)
Length ↓
Wingspan, small to large →		A
< 15 m		BCDEF
1
< 800 m		1A1B1C1D1E1F
2
800 m to < 1 200 m		2A2B2C2D2E2F
3
1 200 m to < 1 800 m		3A3B3C3D3E3F
4
1 800 m and over		4A4B4C4D4E4F
Rows: aeroplane reference field length of the aeroplanes the runway is meant for. Columns: greatest wingspan, from A (below 15 m) to F. The code is a planning tool for the design of the aerodrome; it does not limit the operation of an aircraft.
Figure 4. The code number comes from the aeroplane reference field length and the code letter from the wingspan. The code is a planning tool and does not limit the operation of an aircraft. Original table
Describe this figure

The table has code numbers 1 to 4 down the left and code letters A to F along the top, so each cell is a combined code from 1A to 4F. Code number 1 is a reference field length under 800 m; 2 is 800 m to under 1 200 m; 3 is 1 200 m to under 1 800 m; 4 is 1 800 m and over. Code letter A is a wingspan under 15 m, and the letters rise with wingspan to F. A note says the code is a planning tool for aerodrome design and does not limit the operation of an aircraft.

The figure is a table: code numbers 1 to 4 with length bands down one side, code letters A to F with wingspan bands along the other.

An instrument runway is intended for instrument approach procedures, a non-instrument runway for visual ones. The type changes strip and RESA sizes.

Pavement strength and the altimeter check

For aircraft with an apron mass above 5 700 kg, pavement strength is published as a five-part code starting with the pavement classification number, PCN. For 5 700 kg or less it is the maximum allowable mass and tyre pressure, the form a light-aeroplane pilot most often meets.

Aerodromes also establish a pre-flight altimeter check location, often the apron, whose published elevation is an average with every part within 3 m (10 ft) of it.

Aerodrome data and the condition of the movement area

The operator must determine, document and maintain data about the aerodrome and its services, and provide them to users and to the air traffic and aeronautical information providers. The data include at least the reference point, elevations, reference temperature, dimensions, pavement strength, altimeter check location, declared distances, movement-area condition, disabled-aircraft removal, rescue and firefighting, and visual approach slope indicators. Publication is taught on page 010-08-01.

The operator also monitors the movement area and related facilities, reports operationally significant matters to air traffic and aeronautical information services, and inspects regularly. That covers works, rough or broken surfaces, temporary hazards such as parked aircraft, and failure of visual aids or power. Inspections happen at least once a day for code number 1 or 2, and twice a day for 3 or 4. A NOTAM is issued for, among others, closure or significant change of an aerodrome or runway, hazardous snow, slush, ice or water, and a slippery wet runway.

Rule ADR.OPS.A.005, ADR.OPS.B.015

The operator shall determine, document and maintain aerodrome data, and monitor the movement area and related facilities.

Runway surface condition

A dry runway is free of visible moisture and not contaminated in the area intended to be used. A wet runway is covered by any visible dampness or water up to and including 3 mm deep. Standing water is deeper than 3 mm. A contaminated runway is covered in significant part, within the length and width being used, by one or more surface condition descriptors, such as compacted snow, dry snow, wet snow, slush, frost, ice, wet ice or standing water. A slippery wet runway is a wet runway whose friction over a significant portion has been found degraded.

The runway condition code

The runway condition report, RCR, is a standardised report of surface condition and its effect on performance. The runway condition code, RWYCC, is a number from 0 to 6 describing the effect on deceleration and directional control. The runway condition assessment matrix, RCAM, assigns it. Crews use it to derive stopping distance from the manufacturer's data.

Runway condition assessment matrix: each runway condition code (RWYCC) from 6 to 0, with the surface it stands for and the braking action term that goes with it
RWYCCRunway surface (assessment criteria)Braking action termEffect on braking and control
6DRY——
5FROST
WET (up to 3 mm)
SLUSH, DRY SNOW or WET SNOW up to and including 3 mm		GOODNormal braking and directional control
4SPECIALLY PREPARED WINTER RUNWAY
COMPACTED SNOW at outside air temperature −15 °C and lower		GOOD TO MEDIUM—
3SLIPPERY WET
DRY or WET SNOW (any depth) on top of COMPACTED SNOW
DRY SNOW or WET SNOW more than 3 mm
COMPACTED SNOW above −15 °C		MEDIUMNoticeably reduced braking
2STANDING WATER
SLUSH more than 3 mm		MEDIUM TO POOR—
1ICEPOORSignificantly reduced braking
0WET ICE
WATER ON TOP OF COMPACTED SNOW
DRY or WET SNOW ON TOP OF ICE		LESS THAN POORBraking minimal to non-existent, or directional control uncertain
Green to red: 6 is the best condition, 0 the worst. The number, not the colour, carries the meaning. A dash means the matrix gives no term or wording for that code.
Figure 5. Each runway condition code from 6 to 0 with the surfaces it stands for and its braking action term. The number carries the meaning; the colour only reinforces it. Original table
Describe this figure

The table lists runway condition codes from 6 at the top to 0 at the bottom, each with a colour bar graded from green to red. Code 6 is DRY and has no braking action term; 5 is GOOD, for frost, WET up to 3 mm, and slush, dry snow or wet snow up to 3 mm; 4 is GOOD TO MEDIUM, for specially prepared winter runways and compacted snow at minus 15 degrees Celsius and lower. Code 3 is MEDIUM, for slippery wet, snow on compacted snow, more than 3 mm of dry or wet snow and compacted snow above minus 15 degrees; 2 is MEDIUM TO POOR, for standing water or slush over 3 mm. Code 1 is POOR, for ice; code 0 is LESS THAN POOR, for wet ice, water on compacted snow and snow on ice. The effect column says normal braking and directional control at 5, noticeably reduced at 3, significantly reduced at 1, and minimal or uncertain at 0, with dashes where the matrix gives no wording.

The figure is the matrix as a table graded from green at 6 to dark red at 0, with columns for surface, braking term and effect.

Reading a runway condition report

The report covers each third of the runway, with a code, coverage, depth and description per third. The performance section starts with location indicator, date and time (UTC) and the lower runway number, then gives codes, coverage, depth and description. A made-up example: codes "5/5/3", coverage "50/100/100", depth "NR/NR/07", descriptions "WET/WET/DRY SNOW".

Fields of a runway condition report, performance section Seven fields of an invented report in order, with the value of each: location indicator XXXX, date and time 10141230, runway 09, codes 5/5/3, coverage 50/100/100, depth NR/NR/07, description WET/WET/DRY SNOW. A last field, cleared width, appears only if less than published. Invented example, performance section, in order 1 Aerodrome location indicator (made up) XXXX 2 Date and time of the assessment, UTC 10141230 3 Lower runway designation number 09 Fields 4 to 7, one value per third from 09: 1st 2nd 3rd 4 RWYCC, one code per third 5 5 3 5 Per cent coverage per third 50 100 100 6 Depth in mm, NR = nothing to report NR NR 07 7 Condition description WET WET DRY SNOW 8 Cleared width, only if less than published not used here Third 3: dry snow at 07 mm is over 3 mm, code 3.
Figure 6. An invented performance section, field by field: indicator, date and time, runway, then codes, coverage, depth and description for each third. NR means nothing to report. Original diagram
Describe this figure

Seven numbered rows show an invented report in the order of the performance section, each with its value in a box. The first three are single values: a made-up location indicator XXXX, the date and time in UTC 10141230, and the lower runway designation number 09. Fields 4 to 7 have three boxes each, for the 1st, 2nd and 3rd third from the 09 end: codes 5, 5 and 3, coverage 50, 100 and 100, depth NR, NR and 07 mm, and descriptions WET, WET and DRY SNOW. An eighth dashed row, cleared width, is only used if the width is less than published and is not used here. A note explains that dry snow at 07 mm is over 3 mm and gives code 3.

The figure labels each field of an invented report string.

Per third, coverage under 10 % gives code 6 with nothing reported; 10 to 25 % gives code 6 with the contaminant reported at 25; over 25 % gives the contaminant's code. Depth is reported only for snow, slush and standing water, and standing water from 4 mm up; at 3 mm or less the third is WET.

Now the direction. The written string lists the thirds from the lower runway number. When air traffic passes it to you, the first part is always the first third in your direction of landing or take-off.

The same runway thirds, numbered for each landing direction Runway 09/27 with a wet stretch and a dry snow stretch near the 27 end. Landing on 09 the thirds read 1, 2, 3 left to right with codes 5, 5, 3. Landing on 27 the same thirds read 3, 2, 1 left to right, so the first third is the dry snow one with code 3. Landing on 09: you travel left to right 09 27 WET DRY SNOW 7 mm 1st third code 5 2nd third code 5 3rd third code 3 Landing on 27: you travel right to left 09 27 WET DRY SNOW 7 mm 3rd third code 5 2nd third code 5 1st third code 3 The written report lists the thirds from the 09 end: 5/5/3 for both directions.
Figure 7. The written report lists the thirds from the lower runway number. The first part you hear from air traffic is always the first third in your direction of travel. Original diagram
Describe this figure

Two panels show runway 09/27 with a wet stretch over the first two thirds and a hatched dry snow stretch of more than 3 mm in the third nearest the 27 end. In the first panel an aeroplane lands on 09 and travels left to right, so the thirds are labelled 1st, 2nd and 3rd from left to right, with codes 5, 5 and 3. In the second panel an aeroplane lands on 27 and travels right to left, so the same physical thirds are labelled 3rd, 2nd and 1st from left to right, with the same codes 5, 5 and 3. The first third for the 27 landing is therefore the dry snow third, code 3. A note says the written report lists the thirds from the 09 end, 5/5/3, for both directions.

The figure shows runway 09/27 with a wet stretch and, near the 27 end, a stretch of dry snow deeper than 3 mm. Landing on 09 the thirds read 1-2-3 left to right, codes 5, 5, 3. Landing on 27 they read 3-2-1, so your first third is the snow one, code 3.

Friction measurements are not reported to pilots, because they do not correlate with aeroplane performance. A runway that is simply wet: the report goes to air traffic services only. A contaminated runway, or one wet because of snow or ice clearing or treatment, also goes through aeronautical information, as a SNOWTAM where necessary.

Pilot braking-action reports, from GOOD to LESS THAN POOR, are subjective and depend on aircraft type and mass, so they may not apply to your aeroplane.

Rule SERA.12005(a)(9)

All aircraft shall make a special air-report when the runway braking action encountered is not as good as reported.

Worked examples

Worked example

Example 1: declared distances. Given: a paved runway 1 400 m long, with a 100 m stopway and a 150 m clearway at the far end. For landings in this direction the threshold is displaced by 200 m. Method: TODA adds the clearway, ASDA adds the stopway, LDA subtracts the displacement. Working: TORA = 1 400 m. TODA = 1 400 + 150 = 1 550 m. ASDA = 1 400 + 100 = 1 500 m. LDA = 1 400 − 200 = 1 200 m. Answer: TORA 1 400 m, TODA 1 550 m, ASDA 1 500 m, LDA 1 200 m. The clearway is below half the TORA, so it is allowed.

Worked example

Example 2: comparing LDA with your aeroplane. Given: LDA 1 200 m from example 1. The POH/AFM of an imaginary CS-ABC gives an invented 760 m landing distance from 50 ft, corrections included. Method: available minus required. Working: 1 200 − 760 = 440 m. Answer: 440 m of margin before any safety factor. This does not replace ATO instruction.

In the real world

Real world AAIB Bulletin 5/2018, EW/G2017/12/04, https://assets.publishing.service.gov.uk/media/5ad705ebed915d32a65dbce9/Cessna_182T_Skylane_G-LANS_05-18.pdf

Cessna 182T G-LANS, Bodmin, 9 December 2017.

The Cessna landed on a wet, downhill grass runway, 13, with a published LDA of 598 m. It overran, overturned beyond the runway end, and nobody was hurt. The pilot had first planned the landing for runway 31, where the LDA was 540 m.

Afterwards he recalculated the landing distance from 50 ft, with wet-grass and slope corrections, at about 618 m. That is more than the LDA even before any safety factor. This was a UK aerodrome, not an EU-certified one, but the lesson holds: compare the declared LDA with a corrected POH/AFM landing distance.

Exam traps

Exam trap

"The clearway is extra runway I can use to land or stop on." No. It is an area over which you climb, possibly water. The stopway is for stopping. Neither adds to the LDA.

Exam trap

"TODA is always longer than ASDA." No. They are independent: one adds the clearway, the other the stopway.

Exam trap

"A displaced threshold shortens all declared distances in both directions." No. It reduces only the LDA, only for landings towards that threshold.

Exam trap

"Aerodrome elevation is the average field height." No. It is the elevation of the highest point of the landing area.

Exam trap

"Five millimetres of water is just a wet runway, and 5/5/3 reads the same from both ends." No. Over 3 mm is standing water, code 2. And the written string runs from the lower runway number, while your first part is the first third in your direction.

Explain it back

Explain it back

A friend asks: "My airfield publishes a TORA of 900 m and my POH says I need 700 m, so why should I care about TODA, ASDA and LDA?" Explain in your own words what each of the four means, what a clearway and a stopway add, and why neither helps a landing.

Self-check

  1. A paved instrument runway has code number 3. Which statement about its runway end safety area (RESA) is correct?
    mcq · medium
    Show answer

    A RESA adjoins the end of the strip at each strip end for code number 3 or 4. It is at least 90 m long (240 m as far as practicable) and at least twice the runway width. It is not runway, so it counts in no declared distance, which rules out the first option. The strip, not the RESA, reaches 60 m beyond the runway end, and the RESA lies beyond it, which rules out the second. The last option is wrong because a code 3 runway does not have a 30 m RESA, and RESAs are provided at each strip end, not only the landing end.

    Reference: CS ADR-DSN.C.210(b); CS ADR-DSN.C.215(a)

  2. A runway is 1 800 m long. At the far end there is a 120 m stopway and a 200 m clearway. The threshold for this direction is displaced by 300 m. What is the ASDA for take-off in this direction?
    mcq · medium
    Show answer

    ASDA is TORA plus the stopway: 1 800 + 120 = 1 920 m. 2 000 m is the TODA, because it adds the clearway instead. 1 500 m is the LDA, after the displacement is subtracted. 2 120 m wrongly adds both the stopway and the clearway.

    Reference: Reg. (EU) No 139/2014 Annex I (2), (43), (44); GM1 ADR.OPS.A.005

  3. During an inspection, the operator of an aerodrome finds a broken, rough patch on a taxiway that makes part of the movement area unsafe. What must the operator do?
    mcq · easy
    Show answer

    The operator must monitor the movement area and report operationally significant matters, temporary or permanent, to air traffic services and aeronautical information services. A rough or broken surface is one of the listed conditions. Waiting for the next inspection delays a report the rules want made when the matter is found. Pilots cannot decide usability without being told. Taxiways and aprons are part of the movement area, so the report is not limited to runways.

    Reference: ADR.OPS.B.015(a); GM1 ADR.OPS.A.005; AMC1 ADR.OPS.B.015(b)

  4. A runway condition report for runway 09/27 reads 5/5/3, with the thirds listed from the lower runway number. You are landing on runway 27. Which code applies to the first part of the runway that air traffic passes to you?
    mcq · hard
    Show answer

    The written string lists the thirds from the lower runway number, 09. Air traffic gives them in your direction, so landing on 27 your first third is the one at the 27 end, which is the last number in the string: 3. The string does not start at your end. No rule limits the report to the worst third, and no rule makes the last number apply alone or turns it into code 6.

    Reference: GM2 ADR.OPS.A.065(a)(b)(4)

  5. A third of the runway is reported with 5 mm of water on it. Is that third wet or covered by standing water, which runway condition code does it get, and what would 3 mm of water give instead?
    short · medium
    Show answer

    Water deeper than 3 mm is standing water, which gives runway condition code 2, MEDIUM TO POOR. Water up to and including 3 mm is only a wet runway and gives code 5, GOOD. Depth is reported for standing water from 4 mm up, so at 3 mm or less the third is simply described as WET.

    Reference: Reg. (EU) No 139/2014 Annex I (49), (38h)(f); AMC1 ADR.OPS.B.037(a)

Key concepts

Written with ASD-STE100 writing principles: short sentences, one topic per sentence, active voice, one word for one meaning.

01

Declared distances

The aerodrome publishes four lengths for each runway direction. TORA is the runway length declared available for the take-off ground run, and TODA adds any clearway to it. ASDA adds any stopway to TORA, and with no clearway, stopway or displaced threshold, all four equal the runway length.

Rule: Reg. (EU) No 139/2014 Annex I (2), (43), (44), (24)

Do not: count a clearway or stopway in the LDA.

02

Clearway and stopway

A clearway is a defined rectangular area over which an aeroplane can make part of its initial climb. A stopway is a defined rectangular area at the end of the TORA, where an aeroplane can stop after an abandoned take-off. Neither area adds to the LDA.

Rule: CS ADR-DSN.B.195; CS ADR-DSN.B.200

Do not: land on a clearway or a stopway.

03

Threshold and aerodrome elevation

The threshold is the beginning of the part of the runway usable for landing. A displaced threshold is not at the end of the runway, and it reduces the LDA only for landings towards that threshold. The aerodrome elevation is the elevation of the highest point of the landing area.

04

Runway safety areas

The runway strip includes the runway and any stopway, and reduces damage to an aircraft that runs off the runway. For code number 2, 3 or 4, the strip reaches at least 60 m before the threshold and beyond the runway end. The RESA lies beyond the strip end, is at least 90 m long, and is at least twice the runway width wide.

Rule: CS ADR-DSN.B.155(a); CS ADR-DSN.C.215(a)

Do not: treat the strip or the RESA as usable runway.

05

Runway condition code

The runway condition code, RWYCC, is a number from 0 to 6 that describes the effect of the surface on deceleration and directional control. The runway condition assessment matrix, RCAM, assigns the code from the surface condition, depth and temperature. Each code has a braking action term, for example 5 for GOOD and 1 for POOR.

Rule: AMC1 ADR.OPS.B.037(a)

Do not: read a wet runway as RWYCC 6.

06

Runway condition report

The runway condition report, RCR, gives a code, coverage, depth and description for each third of the runway. The written string lists the thirds from the lower runway number. The first part is always the first third in your direction of landing or take-off.

Rule: ADR.OPS.A.065(a)

Do: check the first part of the runway in your own direction of landing or take-off.

07

Aerodrome data and movement area condition

The operator determines, documents and maintains aerodrome data, such as elevations, declared distances and pavement strength. The operator originates a NOTAM for significant changes, such as a closed runway or hazardous snow, slush, ice or water on the movement area. Inspections happen at least once a day for code number 1 or 2, and at least twice a day for code number 3 or 4.

Rule: ADR.OPS.A.005; ADR.OPS.B.015; AMC1 ADR.OPS.B.015(b); ADR.OPS.A.057(b)

08

EU aerodrome scope

The EU aerodrome rules apply to public-use aerodromes that serve commercial air transport and have a paved instrument runway of 800 m or more. All three conditions apply together. Many small airfields used for PPL(A) training fall under national rules, so their markings and layout need not follow the EU design specifications.

Rule: Reg. (EU) 2018/1139 Art. 2(1)(e); CS ADR-DSN.A.001

Do: read the published aerodrome data before you use any aerodrome.

Flashcards

Print them: A6 landscape cards (PDF, front and back) · 4 cards per A4 landscape sheet (PDF, cut lines) · Key figures deck (PDF, 30 figures)

Print double-sided, flip on the short edge.

  1. 010-09-01-01What does TORA measure?

    The runway length declared available for the ground run of an aeroplane taking off.

  2. 010-09-01-02How is TODA built?

    TORA plus the clearway, if one is provided.

  3. 010-09-01-03How is ASDA built?

    TORA plus the stopway, if one is provided.

  4. 010-09-01-04What does LDA measure?

    The runway length declared available for the ground run of an aeroplane landing.

  5. 010-09-01-05Which declared distance does a clearway add to?

    TODA only. A clearway never adds to LDA.

  6. 010-09-01-06Which declared distance does a stopway add to?

    ASDA only. A stopway never adds to LDA.

  7. 010-09-01-07Does a displaced threshold change the take-off distances?

    No. It reduces the LDA only, and only for landings towards that threshold.

  8. 010-09-01-08How long can a clearway be?

    No longer than half the TORA.

  9. 010-09-01-09How wide is a clearway, each side of the extended centre line?

    At least 75 m each side of the extended centre line.

  10. 010-09-01-10Where is a stopway?

    At the end of the TORA, for stopping after an abandoned take-off.

  11. 010-09-01-11How wide is a stopway?

    The same width as the runway.

  12. 010-09-01-12Is a clearway or a stopway a place to land?

    No. Neither is a place to land.

  13. 010-09-01-13What is the aerodrome elevation?

    The elevation of the highest point of the landing area. It is not an average.

  14. 010-09-01-14What is a threshold?

    The beginning of the part of the runway usable for landing.

  15. 010-09-01-15What is a displaced threshold?

    A threshold that is not at the end of the runway.

  16. 010-09-01-16What does the runway strip protect?

    Aircraft that run off the runway and aircraft that fly over it.

  17. 010-09-01-17How far does the strip extend beyond the runway end for code number 2, 3 or 4?

    At least 60 m before the threshold and beyond the runway or stopway end.

  18. 010-09-01-18What is a RESA?

    An area beyond the strip end, mainly to reduce damage from an undershoot or an overrun.

  19. 010-09-01-19What is the minimum RESA length from the strip end?

    90 m.

  20. 010-09-01-20What is the RESA width?

    At least twice the runway width.

  21. 010-09-01-21What RESA length applies for code number 3 or 4, as far as practicable?

    240 m.

  22. 010-09-01-22What does RWYCC 6 mean?

    Dry.

  23. 010-09-01-23What does RWYCC 0 mean?

    LESS THAN POOR braking, for example on wet ice.

  24. 010-09-01-24Which RWYCC applies to standing water deeper than 3 mm?

    RWYCC 2, MEDIUM TO POOR.

  25. 010-09-01-25Which RWYCC applies to compacted snow at −15 °C or lower?

    RWYCC 4, GOOD TO MEDIUM.

  26. 010-09-01-26What is the depth limit for a WET runway?

    Up to and including 3 mm.

  27. 010-09-01-27What does a third with coverage under 10 % give?

    RWYCC 6, with nothing reported.

  28. 010-09-01-28What does a third with coverage from 10 to 25 % give?

    RWYCC 6, with the contaminant reported at 25 %.

  29. 010-09-01-29What does a third with coverage over 25 % give?

    The RWYCC of that contaminant.

  30. 010-09-01-30From which depth is standing water reported?

    From 4 mm upwards. At 3 mm or less, the third is WET.

  31. 010-09-01-31How are the thirds listed in the written RCR string?

    From the lower runway number.

  32. 010-09-01-32What is the first part of the runway in an ATS report?

    The first third in your direction of landing or take-off.

  33. 010-09-01-33How often is the movement area inspected, for code number 1 or 2?

    At least once a day.

  34. 010-09-01-34How often is the movement area inspected, for code number 3 or 4?

    At least twice a day.

  35. 010-09-01-35What triggers a NOTAM for surface hazards?

    Hazardous snow, slush, ice or water on the movement area.

  36. 010-09-01-36What tolerance applies to a pre-flight altimeter check location?

    Every part within 3 m (10 ft) of the published average elevation.

  37. 010-09-01-37What does the RCR give for each third of the runway?

    A code, coverage, depth and description.

  38. 010-09-01-38Which paved instrument runway length brings an aerodrome into EU scope?

    800 m, together with public use and commercial air transport.

  39. 010-09-01-39What passenger limit can a Member State use for an exemption?

    No more than 10 000 commercial air transport passengers a year.

  40. 010-09-01-40What cargo limit can a Member State use for an exemption?

    No more than 850 cargo-related movements a year.

  41. 010-09-01-41Where is a RESA provided for code number 3 or 4?

    At each end of the strip.

  42. 010-09-01-42Name two items that the movement area monitoring covers.

    For example works, rough or broken surfaces, temporary hazards such as parked aircraft, failure of visual aids or power.

Sources

  1. Easy Access Rules for Aerodromes, Regulation (EU) No 139/2014 (Articles, Annex I definitions, Part-ADR.OR, Part-ADR.OPS) with AMC/GM, March 2026.
  2. EASA, Certification Specifications and Guidance Material for Aerodromes Design (CS ADR-DSN), Issue 6, as published in the Easy Access Rules for Aerodromes, March 2026.
  3. Regulation (EU) 2018/1139 (Basic Regulation), Article 2, EUR-Lex consolidated text of 2 August 2026.
  4. ICAO Annex 14, Aerodromes, Volume I, 9th edition (July 2022), consolidated to Amendment 18.
  5. Easy Access Rules for Standardised European Rules of the Air (SERA), Regulation (EU) No 923/2012, August 2025: SERA.12005 and SERA.12020.
  6. Easy Access Rules for Air Traffic Management/Air Navigation Services, Regulation (EU) 2017/373, March 2025: ATS.OR.530.
  7. UK AAIB, Bulletin 5/2018, EW/G2017/12/04, Cessna 182T G-LANS, Bodmin, 9 December 2017: assets.publishing.service.gov.uk.
  8. EASA Community, Runway Contamination and GRF, post dated 22 January 2026: easa.europa.eu.

This page is educational. It does not replace instruction at your ATO or your aircraft's POH/AFM. Rules change: check the regulation in force.

Glossary

Open the full glossary page