text: Annex to ED Decision 2016/009/R

text: Annex to ED Decision 2016/009/R

text: Annex to ED Decision 2016/009/R Aerodrome category RFF level of protection required 1 1 2 2 3 3 4 4 5 5 6 5 7 6 8 6 9 7 10 7 Table 2 (d) The aerodrome operator, in order to assess whether the rescue and firefighting level of protection to be provided at the aerodrome is appropriate to the aerodrome rescue and firefighting category, should, at least annually, forecast the aeroplane traffic expected to operate at the aerodrome for the next twelvemonth period. Upon knowledge of planned changes to traffic volume and structure, additional assessments might be necessary. In doing so, the aerodrome operator may use all information available from aeroplane operators as well as statistics on aeroplane movements during the year preceding the day of review. (e) Unforeseen circumstances leading to temporary reduction of the aerodrome rescue and firefighting level of protection are considered as unplanned events that result in unavailability of facilities, equipment and resources. (f) For emergency landings and occasions when in the pilot’s-in-command opinion, a diversion or hold may create a more significant hazard, operation of aeroplanes whose required category is higher than the level of protection provided by the aerodrome should be permitted regardless of the rescue and firefighting level of protection available.

text: Annex to ED Decision 2016/009/R

text: Annex to ED Decision 2016/009/R

text: Annex to ED Decision 2016/009/R Example 1 — Wider aeroplane fuselage If an aeroplane has a fuselage length of 47.5 m, column 2 of Table 1 in AMC2 ADR.OPS.B.010(a)(2) indicates RFF category 7. However, the example aeroplane has a fuselage width of 5.5 m, therefore, according to (a)(2) in AMC2 ADR.OPS.B.010(a)(2), the appropriate level of protection is RFF category 8. Example 2 — Longer than average aeroplane length Where operations by aeroplanes larger than the average size in a given category are planned, the quantities of water should be recalculated, and the amount of water for foam production as well as the discharge rates for foam solution should be increased accordingly. The example below is based on an aeroplane with an overall length of 48 m and a maximum fuselage width of 5 m. The quantity of water and the discharge rate of foam solution have been calculated using the ICAO critical-area concept, and increased to reflect the greater practical critical area. Minimum useable amounts of extinguishing agents (based on the provision of foam meeting performance level B) Aerodrome category Water (lt) Discharge rate of foam Dry chemical powder(kg) solution (lt/min) Category 7 minimum 12 100 5 300 225 requirement Requirement following 14 113 6 163 225 recalculation Example 3 — Less than 700 movements in the busiest consecutive 3 months The following examples illustrate the method for the determination of the aerodrome’s rescue and firefighting level of protection when considering the number of movements:

text: Annex to ED Decision 2016/009/R

text: Annex to ED Decision 2016/009/R

text: Annex to ED Decision 2016/009/R 18 m ≤ L < 24 m L × (17 + W) L ≥ 24 m L × (30 + W) where ‘L’ is the overall length of the aeroplane, and ‘W’ is the maximum width of the aeroplane fuselage. (f) In practice, it is seldom that the entire theoretical critical area is subject to fire; thus, a smaller area for which it is proposed to have firefighting capacity is referred to as the practical critical area. As a result of a statistical analysis of actual aeroplane accidents, the practical critical area AP has been found to be approximately two thirds of the theoretical critical area AT, or AP = 0.667 × AT (g) The quantity of water for foam production should be calculated with the following formula: Q = Q1 + Q2, where: — ‘Q’ is the total water required; — ‘Q1’ is the water used to control the fire in the practical critical area; and — ‘Q2’ is the water required after control of the fire has been established, and is needed for maintaining this control and/or extinguishing the remaining fire. (h) The water required for control of the fire in the practical critical area (Q1) may be expressed by the following formula: Q1 = Ap × R × T, where: — ‘Ap’ is the practical critical area; — ‘R’ is the rate of application; and — ‘T’ is the time of application. (i) The amount of water required for Q2 may not be exactly calculated as it depends on a number of variables. The factors considered to be of primary importance are: (1) the maximum gross mass of the aeroplane; (2) the maximum passenger capacity of the aeroplane; (3) the maximum fuel load of the aeroplane; and (4) previous experience (analysis of aeroplane RFF operations). These factors, when plotted on a graph, are used to calculate the total amount of water required for each airport category. The volume of water for Q2, as a percentage of Q1, varies from about 0 % for category 1 aerodromes to about 190 % for a category 10 aerodrome. (j) The relation between Q1 and Q2 for aeroplanes representative of each airport category is shown in the following table: Aerodrome category Q2 = percentage of Q1 1 0 % 2 27 %

text: Annex to ED Decision 2016/009/R 3 30 % 4 58 % 5 75 % 6 100 % 7 129 % 8 152 % 9 170 % 10 190 %

identifier: AMC & GM for Aerodromes — Amendment 1

beslut: ED Decision 2016/009/R

publisher: Europeiska unionens byrå för luftfartssäkerhet

sprak: en

title: AMC & GM for Aerodromes — Amendment 1

serie: amc-gm

text: Annex to Decision 2016/009/R ‘Acceptable Means of Compliance (AMC) and Guidance Material (GM) to Authority, Organisation and Operations Requirements for Aerodromes — Amendment 1’

type: rubrik

text: The Annex to Decision 2014/012/R is hereby amended as follows: The text of the amendment is arranged to show deleted, new or amended text, as shown below: (a) deleted text is marked with strike through; (b) new or amended text is highlighted in grey; and (c) an ellipsis (…) indicates that the remaining text is unchanged in front of or following the reflected amendment.

type: stycke

text: 1. GM1 ADR.OPS.B.010(a)(1) has been amended as follows:

text: GM1 ADR.OPS.B.010(a)(1) Rescue and firefighting services

text: AVAILABILITY AND SCOPE OF RESCUE AND FIREFIGHTING SERVICES Public or private organisations, suitably located and equipped, could be designated to provide the rescue and firefighting service. The fire station housing these organisations should normally be located on the aerodrome, although an off-aerodrome location is not precluded, provided that the response time can be met. The scope of the principal objective of rescue and firefighting services is to save lives in the event of an aircraft accident or incident occurring at, or in the immediate surroundings of, the aerodrome. The operational objective rescue and firefighting service is provided is to create and maintain survivable conditions, to provide egress routes for occupants ,and to initiate the rescue of those occupants unable to make their escape without direct aid. The rescue may require the use of equipment and personnel other than those assessed primarily for rescue and firefighting purposes. Ambulance and medical services are out of the scope of rescue and firefighting services as described in ADR.OPS.B.010. The role and responsibilities of ambulance and medical services during an emergency situation should be included in the aerodrome emergency plan (AEP), according to GM3 ADR.OPS.B.005(a).

text: 2. AMC2 ADR.OPS.B.010(a)(2) has been amended as follows:

text: AMC2 ADR.OPS.B.010(a)(2) Rescue and firefighting services

text: RFFS LEVEL OF PROTECTION (a) The aerodrome operator should ensure that: (…) (2) the RFF aerodrome category for rescue and firefighting is determined according to the Table 1, based on the longest aeroplanes normally using the aerodrome and their fuselage width. If, after selecting the category appropriate to the longest aeroplane’s overall length, that aeroplane’s fuselage width is greater than the maximum width in Table 1, column 3, for that category, then the category for that aeroplane should actually be one category higher. Decision 2014/012/R of the Executive Director of the Agency of 27 February 2014 adopting Acceptable Means of Compliance and Guidance Material to

text: Regulation (EU) No 139/2014

text: ‘AMC/GM for Aerodromes — Initial Issue’

text: Aerodrome category for rescue and firefighting

text: Aerodrome category Aeroplane overall length Maximum fuselage width (1) (2) (3) 1 0 m up to but not including 9 m 2 m 2 9 m up to but not including 12 m 2 m 3 12 m up to but not including 18 m 3 m 4 18 m up to but not including 24 m 4 m 5 24 m up to but not including 28 m 4 m 6 28 m up to but not including 39 m 5 m 7 39 m up to but not including 49 m 5 m 8 49 m up to but not including 61 m 7 m 9 61 m up to but not including 76 m 7 m 10 76 m up to but not including 90 m 8 m

text: (3) the rescue and firefighting level of protection provided is appropriate to the aerodrome category determined using the principles in (2) above except that where the number of movements (landing or take-off) of the aeroplanes performing passenger transportation in the highest category, normally using the aerodrome, is less than 700 in the busiest consecutive three months, the level of protection provided in accordance with (2) above may be reduced by no more than one category below the determined one. (b) Notwithstanding (a),The the aerodrome operator may, should ensure that during anticipated periods of reduced activity (e.g. specific periods of the year or day), reduce the rescue and firefighting level of protection available at the aerodrome. In this case: (1) the level of protection is should be no less than that needed for the highest category of aeroplane planned to use the aerodrome during that time, irrespective of the number of movements.; and (2) the periods of aerodrome operation with reduced rescue and firefighting level of protection should be published in the aeronautical information publication (AIP) or through notice to airmen (NOTAM). (c) Reduction of the level of protection for rescue and firefighting as determined in accordance with Table 1, may be accepted by the Competent Authority. The level of protection required for all-cargo, mail, ferry, training, test, positioning and end-of-life aeroplane operations, including those carrying dangerous goods, irrespective of the number of movements, may be reduced in accordance with Table 2 as follows:

text: 3. AMC3 ADR.OPS.B.010(a)(2) has been amended as follows:

text: AMC3 ADR.OPS.B.010(a)(2) Rescue and firefighting services

text: NUMBER OF RFFS VEHICLES AND RESCUE EQUIPMENT (a) The aerodrome operator should ensure that: (1) the minimum number of rescue and firefighting vehicles at the aerodrome to effectively deliver and deploy the agents specified for the aerodrome category will be in accordance with the following table; and (…)

text: 4. AMC4 ADR.OPS.B.010(a)(2) has been amended as follows:

text: AMC4 ADR.OPS.B.010(a)(2) Rescue and firefighting services

text: EXTINGUISHING AGENTS The aerodrome operator should ensure that: (a) both principal and complementary extinguishing agents are provided at the aerodrome; (…) (da) the quantity of foam concentrates separately provided on vehicles for foam production is in proportion to the quantity of water provided and the foam concentrate selected; (…) (k) a reserve supply of complementary agent equivalent to 100% of the quantity identified in Table 1 is maintained on the aerodrome for vehicle replenishment purposes and sufficient propellant gas is included to utilize this reserve complementary agent; .Complementary agent(s) carried on fire vehicles in excess of the quantity identified in Table 1 may contribute to the reserve; (…) (o) quantities of water and foam concentrate are recalculated and the amount of water and foam concentrate for foam production and the discharge rates for foam solution are increased accordingly, where operations by aeroplanes larger than the average size in a given category are planned; and (oa) Where the level of protection is reduced in accordance with AMC2 ADR.OPS.B.010 (a)(2), a recalculation of quantities of extinguishing agents should be computed based on the largest aeroplane in the reduced category; (ob) For all-cargo, mail, training, test, positioning and end-of-life aeroplane operations, including those carrying dangerous goods, the recalculation of quantities of extinguishing agents should be based on the largest aeroplane in the category specified in Table 2 of AMC2 ADR.OPS.B.010(a)(2);and (…)

text: 5. AMC5 ADR.OPS.B.010(a)(2) has been amended as follows:

text: AMC5 ADR.OPS.B.010(a)(2) Rescue and firefighting services

text: RESPONSE TIME The aerodrome operator should ensure that: (a) rescue and firefighting service achieves a response time not exceeding three minutes with an operational objective of not exceeding two minutes from the time of the initial call to the rescue and firefighting services, to any point of each operational runway, in optimum visibility and surface conditions, and be in a position to apply foam at a rate of, at least, 50 % of the discharge rate specified in AMC4 ADR.OPS.B.010 Table 1; (…)

text: 6. GM4 ADR.OPS.B.010(a)(2) has been amended as follows:

text: GM4 ADR.OPS.B.010(a)(2) Rescue and firefighting services

text: REDUCTION OF RFFS AERODROME CATEGORY LEVEL OF PROTECTION (a) The level of protection could be one category below the determined category if the number of movements of the aeroplanes in the highest RFF aerodrome category normally using the aerodrome is less than 700 in the busiest consecutive three months. (b) The level of protection should be equal to the determined category if the number of movements of the aeroplanes in the highest RFF aerodrome category normally using the aerodrome is equal or above 700 in the busiest consecutive three months. (c) For aerodromes serving exclusively all-cargo aircraft operations, the RFF aerodrome category could be adjusted to a category lower than the one for passenger aircraft operations, provided that the principal objective, to save lives in the event of an aircraft accident or incident, is met. Contingency arrangements to limit the need for changes to the promulgated rescue and firefighting level of protection should be developed. This may involve, for example, a maintenance plan to ensure the mechanical efficiency of equipment and vehicles for rescue and firefighting, and arrangements to cover unplanned absence of the minimum level of personnel including supervisory levels. (d) The following may be considered as Uunforeseen circumstances leading to temporary reduction of the level of protection of the aerodrome rescue and fire fighting services are considered any unplanned events that lead to unavailability of facilities, equipment, and resources, such as: (1)(a) breakdown of RFFS vehicles; (2)(b) staff shortage; (3)(c) unavailability of extinguishing agents; and (4)(d) RFFS response to an accident;. (5)Etc. Such changes, including estimated time of the reduction, should be notified without delay to the appropriate air traffic services (ATS) units and aeronautical information services (AIS) units (see GM1 ADR.OPS.A.005 Aerodrome data) to enable those units to provide the necessary information to arriving and departing aircraft. A temporary reduction should be expressed in terms of the new category of the rescue and firefighting services available at the aerodrome. Where the temporary reduction involves resources not used to calculate the aerodrome RFF category (e.g. specialist rescue equipment for difficult environs), details should be notified. When such a temporary reduction no longer applies, the above units should be advised accordingly.

text: 7. A new GM5 ADR.OPS.B.010(a)(2) has been added as follows:

text: GM5 ADR.OPS.B.010(a)(2) Rescue and firefighting services

text: RESCUE AND FIREFIGHTING LEVEL OF PROTECTION The following examples are intended to illustrate the way in which the various factors to be taken into account when calculating levels of protection should be applied:

text: Aeroplane Overall length Fuselage width Category Movements

text: Airbus A320 37.6 m 4.0 m 6 600 Bombardier CRJ 900 36.4 m 2.7 m 6 300 Embraer 190 36.2 m 3.0 m 6 500 ATR 72 27.2 m 2.8 m 5 200 The longest aeroplanes are categorised by evaluating, based on Table 1 of AMC2 ADR.OPS.B.010(a)(2), firstly their overall length and secondly their fuselage width until 700 movements are reached. It may be seen that the number of movements of the longest aeroplanes in the highest category totals more than 700. The aerodrome, in this case, is category 6.

text: Airbus A350-900 66.8 m 6.0 m 9 300 Boeing 747-8 76.3 m 6.5 m 10 400 Airbus A380 72.7 m 7.1 m 10 400

text: The longest aeroplanes are categorised by evaluating, based on Table 1 of AMC2 ADR.OPS.B.010(a)(2), firstly their overall length and secondly their fuselage width until 700 movements are reached. It may be seen that the number of movements of the longest aeroplanes in the highest category totals more than 700. It may also be noted that when evaluating the category appropriate to the overall length of Airbus A380, e.g. category 9, the category selected is actually one level higher as the aeroplane’s fuselage width is greater than the maximum fuselage width for category 9. The aerodrome, in this case, is category 10.

text: Boeing 737-900ER 42.1 m 3.8 m 7 300 Bombardier CRJ 900 36.4 m 2.7 m 6 500 Airbus A319 33.8 m 4.0 m 6 300

text: The longest aeroplanes are categorised by evaluating, based on Table 1 of AMC2 ADR.OPS.B.010(a)(2), firstly their overall length and secondly their fuselage width until 700 movements are reached. It may be seen that the number of movements of the longest aeroplanes in the highest category totals only 300. The minimum category for the aerodrome, in this case, is be category 6, which is one category level below that of the longest aeroplane.

text: Airbus A380 73.0 m 7.1 m 10 300 Boeing 747-8 76.3 m 6.5 m 10 200 Boeing 747-400 70.7 m 6.5 m 9 300

text: The longest aeroplanes are categorised by evaluating, based on Table 1 of AMC2 ADR.OPS.B.010(a)(2), firstly their overall length and secondly their fuselage width until 700 movements are reached. It may be seen that the number of movements of the longest aeroplanes in the highest category totals only 500. It may also be noted that when evaluating the category appropriate to the overall length of Airbus A380, e.g. category 9, the category selected is actually one level higher as the aeroplane’s fuselage width is greater than the maximum fuselage width for category 9. The minimum category for the aerodrome, in this case, is category 9, which is one category level below that of the longest aeroplane.

text: Airbus A321 44.5 m 4.0 m 7 100 Boeing 737-900ER 42.1 m 3.8 m 7 300 ATR 42 22.7 m 2.9 m 4 500

text: The longest aeroplanes are categorised by evaluating, based on Table 1 of AMC2 ADR.OPS.B.010(a)(2), firstly their overall length and secondly their fuselage width until 700 movements are reached. It may be seen that the number of movements of the longest aeroplanes in the highest category totals only 400. The minimum category for the aerodrome is category 6. However, even if there is a relatively wide range of difference between the length of the longest aeroplane (Airbus A321) and the aeroplane for which the 700th movement is reached (ATR 42), the minimum category for the aerodrome may only be downgraded to category 6.

text: Example 4 — Anticipated periods of reduced activity The level of protection should be no less than that needed for the highest category of aeroplanes planned to use the aerodrome during that period. If the aerodrome has promulgated RFFS category 7, but between 23:00 and 6:00, the largest aeroplane operating has an overall length of 27.5 m and a maximum fuselage width of 3.9 m, the promulgated category may be downgraded to category 5 for that time frame. Example 5 — All-cargo and mail aeroplane operations including dangerous goods An all-cargo aeroplane is an aeroplane operated for the transportation of cargo including dangerous goods. If an all-cargo aeroplane has an overall length of 47.5 m and a maximum fuselage width of 4.2 m, according to Table 1, category 7 is indicated. As the aeroplane is an all-cargo one, according to Table 2, a reclassification to category 6 may be applied.

text: 8. A new GM6 ADR.OPS.B.010(a)(2) has been added as follows:

text: GM6 ADR.OPS.B.010(a)(2) Rescue and firefighting services

text: CRITICAL AREA FOR CALCULATING QUANTITIES OF WATER (a) The ICAO critical-area concept is applied for rescuing the occupants of an aeroplane. It seeks to control only that area of fire adjacent to the fuselage. The objective is to safeguard the integrity of the fuselage and maintain tolerable conditions for the occupants of the aeroplane. The size of the controlled area required to achieve this for a specific aeroplane has been determined by experimental means. (b) There is a need to distinguish between the theoretical critical area, within which it may be necessary to control the fire, and the practical critical area, which is representative of actual aeroplane accident conditions. The theoretical critical area serves only as a means of categorising aeroplanes in terms of the magnitude of the potential fire hazard in which they may become involved. It is not intended to represent the average maximum or minimum spill fire size associated with a particular aeroplane. The theoretical critical area is a rectangle having as one dimension the overall length of the aeroplane and as the other dimension a length which varies with the fuselage’s length and width. (c) From experiments performed, it has been established that for an aeroplane with a fuselage length equal to or greater than 24 m, in wind conditions of 16–19 km/h and at right angles to the fuselage, the theoretical critical area extends from the fuselage to a distance of 24 m upwind and 6 m downwind. For smaller aeroplanes, a distance of 6 m on either side is adequate. To provide for a progressive increase in the theoretical critical area however, a transition is used when the fuselage length is between 12 and 24 m. (d) The overall length of the aeroplane is considered appropriate for the theoretical critical area as the entire length of the aeroplane must be protected from burning. If not, the fire might burn through the skin and enter the fuselage. Moreover, other aeroplanes, such as T-tail ones, often have engines or exit points in their extended portion. (e) The formula for the theoretical critical area AT should be the following:

text: Overall length Theoretical critical area AT L < 12 m L × (12 + W) 12 m ≤ L < 18 m L × (14 + W)

text: 9. AMC1 ADR.OPS.C.005 has been amended as follows:

text: AMC1 ADR.OPS.C.005 General

text: MAINTENANCE PROGRAMME (…) (e) equipment and vehicles, including those used by rescue and firefighting services, which are necessary for the safety of aerodrome operations; and (…)

type: vagledning

utgivare: easa


text: Minimum acceptable lLength of irregularity (m)

text: Surface Irregularity 3 6 9 12 15 20 30 45 60

text: Acceptable surface irregularity height 2.9 3.8 4.5 5 5.4 5.9 6.5 8.5 10 (cm) Maximum surface irregularity height (or 3 3.5 4 5 5.5 6 6.5 8 10 depth) (cm) Temporary Tolerable acceptable surface 3.5 6.5 7.5 8 9 13 15 5.5 11 irregularity height (or depth) (cm) 3.9 6.8 7.8 8.6 9.6 13.6 16 Excessive surface irregularity height 5.8 7.6 9.1 10 10.8 11.9 13.9 17 20 (cm)

identifier: AMC & GM for Aerodromes — Amendment 2

beslut: ED Decision 2017/017/R

title: AMC & GM for Aerodromes — Amendment 2

text: Annex to ED Decision 2017/017/R

text: ‘Acceptable Means of Compliance (AMC) and Guidance Material (GM) to Authority, Organisation and Operations Requirements for Aerodromes — Amendment 2’

text: The Annex to ED Decision 2014/012/R is amended as follows: The text of the amendment is arranged to show deleted text, new or amended text as shown below: — deleted text is struck through; — new or amended text is highlighted in grey; — an ellipsis ‘(…)’ indicates that the rest of the text is unchanged.

text: 1. GM1 ADR.OPS.A.005 is amended as follows: GM1 ADR.OPS.A.005 Aerodrome data (…) (b) Strip/Runway End Safety Area/Stopway (1) Length, width to the nearest metre or foot; and (2) Surface type.; and (3) Arresting system – location (which runway end) and description. (…)

text: 2. A new AMC4 ADR.OPS.B.070 is added as follows: AMC4 ADR.OPS.B.070 Aerodrome works safety CLOSED RUNWAYS AND TAXIWAYS, OR PARTS THEREOF The aerodrome operator should ensure that: (a) a closed marking as defined in CS ADR.DSN.R.855(c) is displayed on a temporarily closed runway, or taxiway, or a portion thereof, except that such a marking may be omitted when the closing is of short duration and adequate warning by air traffic services is provided; (b) lighting on a closed runway or taxiway, or a portion thereof is not operated, except as required for maintenance purposes; and (c) in addition to closed markings, when the runway, taxiway, or portion thereof is closed and is intercepted by a usable runway or taxiway which is used at night, unserviceability lights as defined in CS ADR.DSN.R.870(c) should be placed across the entrance to the closed area at intervals not exceeding 3 m.

text: 3. A new GM5 ADR.OPS.B.070 is added as follows: GM5 ADR.OPS.B.070 Aerodrome works safety USE OF TEMPORARY RUNWAY MARKINGS (a) Circumstances may occur when it is not practicable to install permanent markings, for example during runway resurfacing. In order to provide sufficient visual guidance to aircraft, the following markings should be considered: (1) runway centre line; (2) taxiway centre line lead on/off; (3) runway edge line; (4) runway threshold; and (5) touchdown zone and aiming point markings. (b) Centre line and edge marking widths can be replaced by temporary markings of reduced width from 0.9 m to 0.6 m, if required. (c) Touchdown zone and aiming point markings should be painted as soon as possible after the resurface of the runway. (d) Threshold markings should be painted as soon as possible, using temporary materials before making them permanent.

text: 4. AMC1 ADR OPS.B.080 is amended as follows: AMC1 ADR.OPS.B.080 Marking and lighting of vehicles and other mobile objects (…) (c) When flags are used to mark mobile objects, they should comply with the applicable CSs be displayed around, on top of, or around the highest edge of the object. Flags should not increase the hazard presented by the object they mark. (d) When flags are used to mark mobile objects they should not be less than 0.9 m on each side and should consist of a chequered pattern, each square having sides of not less than 0.3 m. The colours of the pattern should contrast each with the other and with the background against which they will be seen. Orange and white, or alternatively red and white should be used, except where such colours merge with the background.

text: 5. AMC1 ADR.OPS.C.010 is amended as follows: AMC1 ADR.OPS.C.010 Pavements, other ground surfaces and drainage (…) (g) The surface of a paved runway should be evaluated when constructed or resurfaced to determine that the surface friction characteristics achieve the design objectives.

text: 6. GM3 ADR OPS.C.010(b)(2) is amended as follows: GM3 ADR.OPS.C.010(b)(2) Pavements, other ground surfaces, and drainage RUNWAY SURFACE EVENNESS (a) The operation of aircraft and differential settlement of surface foundations will eventually lead to increases in surface irregularities. Small deviations in the above tolerances will not seriously hamper aircraft operations. In general, isolated irregularities of the order of 2.5 cm to 3 cm over a 45 m-distance are tolerable acceptable, as shown in Figure 1. Although maximum acceptable deviations vary with the type and speed of an aircraft, the limits of acceptable surface irregularities can be estimated to a reasonable extent. The following table describes maximum acceptable, and temporarily acceptable tolerable and excessive limits.: Table 1 If the maximum limits are exceeded, corrective action should be undertaken, as soon as reasonably practicable, to improve the ride quality. If the temporarily acceptable limits are exceeded, the portions of the runway that exhibit such roughness should have corrective measures taken immediately if aircraft operations are to be continued. (1) If the surface irregularities exceed the heights defined by the acceptable limit curve but are less than the heights defined by the tolerable limit curve, at the specified minimum acceptable length, herein noted by the tolerable region, then maintenance action should be planned. The runway may remain in service. This region is the start of possible passenger and pilot discomfort. (2) If the surface irregularities exceed the heights defined by the tolerable limit curve, but are less than the heights defined by the excessive limit curve, at the specified minimum acceptable length, herein noted by the excessive region, the maintenance corrective action is mandatory to restore the condition to the acceptable region. The runway may remain in service but should be repaired within a reasonable period. This region could lead to the risk of possible aircraft structural damage due to a single event or fatigue failure over time. (3) If the surface irregularities exceed the heights defined by the excessive limit curve, at the specified minimum acceptable length, herein noted by the unacceptable region, then the area of the runway where the roughness has been identified warrants closure. Repairs are required to restore the condition within the acceptable limit region and the aircraft operators may be advised accordingly. This region runs the extreme risk of a structural failure and must be addressed immediately. (b) The term ‘surface irregularity’ is defined herein to mean isolated surface elevation deviations that do not lie along a uniform slope through any given section of a runway. For the purposes of this concern, a ‘section of a runway’ is defined herein to mean a segment of a runway throughout which a continuing general uphill, downhill, or flat slope is prevalent. The length of this section is generally between 30 and 60 m, and can be greater, depending on the longitudinal profile and the condition of the pavement. (c) The maximum tolerable step-type bump, such as that which could exist between adjacent slabs, is simply the bump height corresponding to zero bump length at the upper end of the tolerable region of the roughness criteria of Figure 1. (d) Deformation of the runway with time may also increase the possibility of the formation of water pools. Pools as shallow as approximately 3 mm in depth, particularly if they are located where they are likely to be encountered at high speed by landing aeroplanes, can induce aquaplaning which can then be sustained on a wet runway by a much shallower depth of water. Improved guidance regarding the significant length and depth of pools relative to aquaplaning is the subject of further research. It is, of course, especially necessary to prevent pools from forming whenever there is a possibility that they might become frozen. (e) Macrotexture and microtexture are taken into consideration in order to provide the required surface friction characteristics. This normally requires some form of special surface treatment. Figure 1