Minimizing the Impact of Runway Arresting Systems on Commercial Airplane Operations

MINIMIZING THE IMPACT OF RUNWAY ARRESTING SYSTEMS ON COMMERCIAL AIRPLANE OPERATIONS

Many airports throughout the world have joint commercial-military operations. Runways at these airports often are equipped with arresting gear systems for tactical military aircraft to use for landing. These systems pose a potential damage and safety hazard to commercial airplanes that use the same runways. Airports and airlines can take steps to help ensure safe commercial operations under such circumstances. Measures include writing airport procedures specifically for commercial airplane operations, modifying existing arresting systems, reducing declared landing and takeoff distances, and increasing inspections of airplanes with nosegear spray and gravel deflectors.

BRAD BACHTEL AIRPORT TECHNOLOGY AERO FACILITIES LEAD, AIRPORT OPERATIONS BOEING COMMERCIAL AIRPLANES GROUP 23 TYPES OF AIRCRAFT They sometimes are used for special pur- arresting-cable installations. An aircraft 1 ARRESTING SYSTEMS poses, such as stopping the space shuttle. operating on runway 10R would use the f the nearly 36,000 airports around the world cable at the far end for both landing and The three basic types of aircraft arrest- Aircraft arresting cables. that are classified as civil, military, or joint-use, ing systems are barriers, cables, and aborted takeoff unless the aircraft had an approximately 3,800 are used for scheduled Arresting cables span the runway emergency, at which point the arresting engineered materials arresting systems surface and are engaged by the aircraft (EMAS). The first two systems are gear nearest the approach end of the run- commercial service. Worldwide, an estimated 2,000 aircraft arresting gear hook (fig. 2). Cables primarily military systems used for tac- way would be used. arresting systems are installed at facilities in 64 countries. are typically 1 to 1 1/4 in (2.5 to 3.2 cm) tical aircraft, such as fighter and attack The highest concentration of these systems is on military in diameter and suspended 1 1/2 to 3 in The installation criteria for cable jets. The third system recently has been systems on commercial runways are runways or where the military is a major tenant of a com- developed and is used at commercial (3.8 to 7.6 cm) above the pavement surface by rubber donuts 6 in (15.2 cm) identified in the U.S. Federal Aviation mercial airport. Commercial operators mainly encounter airports that do not have sufficient Administration (FAA) Advisory Circular safety areas at the end of the runway. in diameter. Used primarily by aircraft these systems at joint commercial-military airports or when AC 150/5220-9, Aircraft Arresting (See “U.S. and International Aircraft built in the United States and Europe, Systems for Joint Civil/Military Airports. operating charters to military airfields. If the nosegear spray Arresting Systems” on p. 31.) arresting cables have been used by the and gravel deflectors used on some commercial airplanes military since the late 1920s on aircraft The location of the cable is marked Aircraft arresting barriers. on the runway by a series of reflective come in contact with the arresting systems, the deflectors carriers and for land-based runways. These devices, which do not depend discs 10 ft (3 m) in diameter painted could shatter, creating foreign object debris (FOD). In extreme Three main factors determine where “identification yellow.” These discs are on arresting hooks on aircraft, stop an cables are located on runways: the direc- cases, the FOD could damage a critical airplane system. aircraft by absorbing its forward laid out with 30 ft (9.1 m) between tion of engagement (unidirectional or momentum in a landing or aborted centers and extend the full width of To help minimize the impact of runway arresting systems on takeoff overrun. These systems are most bidirectional); the runout of the system, the runway (fig. 2). (See location identi- commercial operations, airlines need to know the following: commonly net devices (fig. 1), but they which is the distance from the cable fication in “Common Terms” on p. 30.) to the point at which the aircraft stops 1. Types of aircraft arresting systems. also include older devices that catch the main gear struts. The barriers typi- (typically 950 to 1,200 ft, or 290 to 360 m); Engineered materials arresting 2. Operational concerns for airlines. cally are located in the overrun of the and whether the system is typically used systems (EMAS). runway, are unidirectional, and can have under visual meteorological conditions EMAS, which are constructed of high- 3. Measures to help ensure safe commercial operations. collocated or interconnected arresting or instrument meteorological conditions. energy-absorbing materials of selected cables as part of their configuration. Figure 3 shows the typical locations for strength, are located in the safety area,

AERO AERO 24 25 or overrun, of the runway. They are MA-1/MA-1A TYPE BARRIER NET TYPICAL ARRESTING GEAR CABLE When most operations are 1 designed to crush under the weight of 3 INSTALLATION LOCATIONS ON A RUNWAY conducted under instrument FIGURE commercial airplanes as they exert FIGURE meteorological conditions deceleration forces on the landing gear. Main control box 2,200 - 2,500 ft These systems do not affect the normal (671 - 762 m) Adapter webbing landing and takeoff of airplanes. More information concerning EMAS is in FAA 10R Arresting gear Aircraft travel Stanchion Advisory Circular AC 150/5220-22, intermediate Engineered Materials Arresting Systems cables 28L (EMAS) for Aircraft Overruns. 1,500 - 1,800 ft (457 - 549 m) Runway overrun area OPERATIONAL CONCERNS 2 When most operations are conducted under FOR AIRLINES visual meteorological conditions Airlines have numerous concerns about operating commercial airplanes Stanchion Cable 737-200 NOSEGEAR GRAVEL MD-80 NOSEGEAR SPRAY/FOD arresting on runways with aircraft arresting Chain 4 DEFLECTOR 5 DEFLECTOR systems. These include airplane FIGURE FIGURE nosegear interference, trampling of Lifter strap the arresting cable, adjustments to declared distances, dealing with arresting barriers, runway availability, airplane maintenance, and uninten- Auxiliary control box tionally engaging arresting systems. Nosegear interference. Some commercial airplanes have unique nosegear devices to deflect either spray or foreign objects. A 737-200 that operates on gravel runways has a nosegear gravel-deflector unit with BAK-12 ARRESTING GEAR CABLE 2 a ground clearance of 3 1/2 to 6 in FIGURE (8.9 to 15.2 cm) (fig. 4). The MD-80, removed, in accordance with the Adjustments to declared distances. MD-90, and 717 airplanes are equipped minimum equipment list, the airplane Some airlines that operate on runways with a combination nosegear spray–FOD is limited to operating on dry runways with arresting cables have reduced deflector for normal operations (fig. 5). until the deflector is replaced. the available runway length by the The ground clearance of this deflector distance from the operational end of is 3/4 to 1 1/2 in (1.9 to 3.8 cm). Trampling of the arresting cable. the runway, or threshold, to the cable. A few DC-9-50 airplanes also use the If an operator considers the trampling, For example, an 8,000-ft (2,438-m) same nosegear deflector for additional or rolling over, of a cable to be too FOD protection. Because most arresting rough on the airplane, the donuts runway could be reduced to 5,000 ft cables are 1 to 1 1/4 in (2.5 to 3.2 cm) that elevate the arresting cable above (1,524 m) of usable runway length in diameter and suspended by rubber the runway surface can be moved for each of the following declared donuts 6 in (15.2 cm) in diameter, to the sides of the runway during distances: takeoff distance available, nosegear deflectors are at risk of being commercial operations. This allows the takeoff runway available (TORA), damaged if a donut is struck. cable to rest directly on the pavement accelerate stop distance available, and landing distance available (fig. 6). Normal procedure is for the rubber surface, minimizing the bump effect donuts to be approximately 6 ft (1.8 m) on the airplane. If the distance between the apart, starting 3 ft (0.91 m) from the It is important to note that the cable threshold and the cable is not used, runway centerline on runways 200 ft must be kept under tension, whether however, the remaining runway (61 m) or less in width. For runways lying on the pavement or elevated substantially reduces the available wider than 200 ft (61 m), the donuts by the donuts. Otherwise, the cable payload on a 737-800 and MD-83 are placed 8 ft (2.4 m) apart. To mini- could be lifted by the airplane landing operation, based on the conditions of mize potential damage to the nosegear gear and contact the bottom of the a standard day, optimal flap setting, deflectors, airplanes with such attach- fuselage or antennae located on the zero wind, no obstacles, and zero ments should slow-taxi over the cable, lower fuselage. (See rigged and down, slope (table 1). This method may be avoiding the donuts. If the nosegear rigged and up, and out of battery in usable for a short-haul flight, but it is spray deflector is damaged and “Common Terms” on p. 30.) not a preferred long-term solution.

AERO AERO 26 27 ADJUSTMENT TO DECLARED RUNWAY DISTANCES BAK-14 RETRACTABLE HOOK BAK-14 RETRACTABLE HOOK 6 7a CABLE SYSTEM, LOWERED 7b CABLE SYSTEM, RAISED FIGURE FIGURE FIGURE

1,500 ft 5,000 ft 1,500 ft (457 m) (1,524 m) (457 m) 10R 28L

Arresting gear cables

Dealing with arresting barriers. EXAMPLE OF REDUCED RUNWAY LENGTHS ON WEIGHT Nets are typically located in the over- 1 run area near the runway threshold. If TABLE the net is in the raised position at the Takeoff weight Weight loss departure end, it should be treated as Airplane Airfield length an obstruction that has to be cleared ft (m) lb (kg) lb (kg) by 35 ft in accordance with the FAA federal aviation regulations and an 737-800 8,000 (2,438) 174,000 (78,926) — ■ If the airport has parallel runways, normally only one of the ■ Although not considered an optimal solution, the runway adjustment made to the TORA. There two runways has the arresting systems installed. Consider length can be reduced. This is feasible if the runway is of are rare situations in which a net has 5,000 (1,524) 140,300 (63,640) 33,700 (15,286) limiting commercial operations to the runway without the sufficient length that the mission of the airplane can be been located in the actual runway. arresting systems. achieved on the usable runway distance between arresting In these cases, provided the net lies ■ Coordinate the permanent removal of the arresting systems. gears installed at each end of the runway. At a minimum, flat on the runway and is under tension, operators may consider reducing only the distance from the MD-83 8,000 (2,438) 159,700 (72,440) — The military aircraft using the runways may no longer need it can be rolled over. If the net is the arresting gear; the gear, or at least the cable, could be approach end of the runway to the gear. bunched and lying on top of the runway, removed. (See derigged in “Common Terms” on p. 30.) ■ the airplane should not cross it. 5,000 (1,524) 131,300 (59,558) 28,400 (12,882) Operators may wish to increase the frequency of maintenance ■ Install a system to raise and lower the arresting cable inspection of the nosegear and lower fuselage areas for air- Runway availability. flush into a track on the runway (fig. 7). This modification, planes that routinely operate over arresting-gear cables. A commercial airplane following a mili- referred to as BAK-14, takes an existing tary aircraft could experience a delay in thought that the cable had made In 1995, an MD-88 was starting its arresting cable and allows the air traffic landing if the military aircraft engages contact with the belly of the airplane. takeoff roll when the nose landing gear control tower to remotely raise the arresting 8 BAK-12 DISCONNECTED AND AT SIDE OF RUNWAY the arresting gear. The flight crew of the For airlines that routinely operate on snagged the arresting gear, bringing cable for military operations and lower it FIGURE commercial airplane should expect to runways with arresting-gear cables, the airplane to a halt. It was inspected into a track flush-mounted on the runway execute a missed approach while additional visual inspections may be with no damage found and dispatched for commercial operations. At the majority the military aircraft is removed and the conducted depending on the type shortly thereafter. of joint-use airports in the United States, arresting gear reset. Typical cycle times of arresting systems installed and to this modification has been made to the MEASURES TO HELP ENSURE for arresting gear can vary from 3 to what extent the airplane interacts standard BAK-9/12/13 systems that previ- 3 SAFE COMMERCIAL OPERATIONS 10 minutes depending on the type of with the system. ously were supported by the rubber donuts. system. (See cycle time and reset time The key to dealing with the presence (See BAK in “Common Terms” on p. 30.) in “Common Terms” on p. 30.) Unintentionally engaging of arresting cables on runways is co- arresting systems. ordination among the airline operator, ■ Disconnect the cable and lay it on the side Airplane maintenance. Occurrences of commercial airplanes the airport operator, and the agency of the runway during periods of commercial If the flight crew believes the airplane being engaged or tangled in arresting having control of the arresting system. operations (fig. 8). This is a workable nosegear has contacted one of the hard cables are rare. In the 1970s, a DC-10 Educating the various parties on the solution provided the scheduled commercial rubber donuts supporting an arresting- had a rejected takeoff during a flight operational needs of commercial air- operations do not interfere with the flight gear cable, a visual inspection of test. In this case, the fuse plugs on the planes can alleviate many limitations. schedule of the military aircraft. Or slide the the nosegear spray deflector should leading tires on one main landing gear Six ways to minimize the impact of rubber donuts to the edge of the runway be conducted to verify whether it has had deflated, and during the takeoff arresting systems located on runways so that the cable lies flat on the pavement been damaged. A similar visual inspec- roll the arresting cable was snagged, used by commercial airplanes are shown but is still under tension. The airplane tion would apply if the flight crew causing the airplane to stop. in the following list. then can roll over the top of the cable.

AERO AERO 28 29 U.S. AND INTERNATIONAL AIRCRAFT ARRESTING SYSTEMS TAIL HOOK SYSTEMS MAIN STRUT OR WING ENGAGEMENT SYSTEMS Bidirectional Unidirectional BAK-6 Water squeezer MA-LA Web barrier between stanchions attached to a BAK-9 Rotary friction brake chain energy absorber. Designed primarily for main strut engagement, but tests reveal successful hook BAK-12 Rotary friction brake backup capability. There are three types of installation for the BAK-12 system: MA-LA modified or MA-1A/E-5 SUMMARY ■ Standard BAK-12 — 950-ft runout, 1-in cable, and Web barrier between adjustable stanchions 40,000-lb weight setting. combined with a hook pickup cable and chain Commercial airplanes energy absorber. ■ can safely use runways with Extended BAK-12 — 1,200-ft runout, 1-1/4-in cable, and 50,000-lb MA-1A/BAK-9 or MA-1A/BAK-12 weight setting. Web barrier between adjustable stanchions com- aircraft arresting systems. ■ Dual BAK-12 — Two energy absorbers on each side of the runway bined with a hook pickup cable and a mechanical Safe operation requires planning connected to a single cable; runout varies. energy absorber (bidirectional on request). MAAS Essentially a BAK-12 system mobilized on a specially BAK-15 Web barrier between stanchions attached to an by, and coordination among, developed trailer. Basic system has 990-ft runout energy absorber (water squeezer, rotary friction, commercial airplane operators, and is equivalent to standard BAK-12. MAAS may be chain). Designed for wing engagement. modified to accommodate different configurations BAK-15 (NI) Web barrier between stanchions interconnected airport authorities, and the equivalent to various BAK-12 systems. with a hook pickup cable and energy absorber. agencies that control the BAK-13 Rotary hydraulic System is called BAK-15 with Net Interconnect (NI). E28 Rotary hydraulic (water brake) BEFAB 6:3* Description not available (N/A) arresting systems. M21 Rotary hydraulic (water brake) mobile BEFAB 12:3* N/A BEFAB 21:2 N/A Unidirectional BEFAB 24:4** N/A E5/E5-1/E5-3 Chain type. Rated by chain weight and length. The RAF MK-6 N/A rating is used to determine the maximum aircraft engaging speed. A dry rating applies to a stabilized RAF MK-12A All nylon net surface (dry or wet), while a wet rating takes into RAF TYPE A N/A account the amount (if any) of wet overrun that is not capable of withstanding the aircraft weight. RAF TYPE B N/A (net only; may be attached to energy absorber from any arresting gear) Foreign cable SAFE-BAR (Safe-land barrier) 34B-1A, 1B, 1C Rotary hydraulic (water brake) N/A (engage with closed canopy) 44B-2E, 2F, 2H, 2I, 2L, 3A, 3H, 3L, 4C, 4E, 4H 61QSII Barricade net system Rotary hydraulic (water brake) 62NI Net barrier with hook cable interconnect 500S, 500S-4, 500S-6 63PI Dual-cable interconnect for hook engagement COMMON TERMS Rotary friction A30 Aerazur 30-element net (F30) 500S-8 (TAG) Rotary friction (trans-arresting gear) A40 Aerazur 40-element net (F40) Arresting-Gear Cable Status: ■ out of battery (slack cable) — The or departure end, runway designa- 500S-8 Rotary friction HOOK CABLE Unspecified type of tail hook engagement cable is extended across the runway tion, and position in hundreds of 1300 Rotary hydraulic (water brake) ■ derigged — The cable is removed feet from the threshold. For example, HP-NET Adec high-performance net from the runway surface and is not but is not under tension. 2800 Rotary hydraulic (water brake) the location identification J-BAR Generic barrier (non-hook cable) engagement an operational concern. BAK — U.S. designation for a barrier AAE-64 Rotary hydraulic (water brake) “extended runout BAK-12 at +1,500 MA-1 Net barrier main gear cable engagement arresting system. Non-U.S. arresting BEFAB 8:3, 20:4, 56:2 ■ rigged and down — The cable is on approach runway 36” indicates NET Unspecified type of net engagement systems carry other designations. Pneumatic disc brake under tension across the runway but a 1,200-ft runout BAK-12 arresting (See “U.S. and International Aircraft DUALBAK-12 Rotary friction UNK Unknown not elevated off the surface by use system located 1,500 ft beyond the Arresting Systems” on p. 31.) E5-1, E5-2, E5-3 Chain of rubber donuts (BAK-9/12) or rub- threshold of runway 36. DEVICES USED WITH SOME AIRCRAFT ARRESTING SYSTEMS ber elevation arms (BAK-14 mod). cycle time — A measure of time E6 Chain BAK-11 Pop-up engaging device with a mechanical energy reset time — The time required to between engagement of an aircraft E15, E27 Rotary friction absorber (BAK-9, BAK-12) to engage main struts ■ rigged and up — Also referred ready the arresting system for another and the point when the arresting E28 Rotary hydraulic (water brake) BAK-14 A device that raises a hook cable out of a slot in to as the gear being “in battery.” engagement after aircraft release. system is certified fully operational the runway surface and is remotely positioned for Means that the cable is under tension (This does not include time to dis- M21 Rotary hydraulic (water brake) mobile and ready for another engagement. engagement by the tower on request across the runway and elevated off engage the aircraft from the arresting MAG I thru MAG X Rotary hydraulic (mobile arresting gear) the surface by use of rubber donuts location identification — A descrip- system but does include the time PAAG Portable aircraft arresting gear (British) * May alternatively be fitted with a cable (BAK-9/12/13) or rubber elevation tion identifying the location of required to inspect and certify the UNKAGEAR Unknown type of energy absorber ** Cable attached arms (BAK-14 mod). arresting systems by the approach system fully operational.) SOURCE: THE U.S. DEPARTMENT OF DEFENSE (DOD) EN ROUTE SUPPLEMENT, A DOD FLIGHT INFORMATION PUBLICATION (FLIP) PRODUCED AND DISTRIBUTED BY THE NATIONAL IMAGERY AND MAPPING AGENCY (NIMA).

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