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AGA - 9.0 AIRCRAFT ARRESTING SYSTEMS

 

9.1 Engineered Material Arresting Systems (EMAS)

NOTE: No EMAS are currently installed in Canada. This section is being published to educate the aviation community prior to EMAS being installed in Canada.

9.1.1 System Description

EMAS is an arresting system designed for transport category aeroplanes in the event of a runway overrun. An EMAS bed is designed to stop an overrunning aeroplane by exerting predictable deceleration forces on its landing gear as the EMAS material crushes. The strength of the arrester bed is designed to decelerate the aeroplane without structural failure to the landing gear. The beds are made up of a grouping of blocks of crushable cellular concrete that will reliably and predictably crush under the weight of an aeroplane.

In order to arrest an aeroplane overrunning a runway end, EMAS beds are placed beyond the end of a runway and in alignment with the extended runway centerline. 

Photograph of an Engineered Material Arresting System installation

Photograph of an EMAS installation
(The EMAS bed is the grey area under the yellow chevrons)

9.1.2 System Depiction 

The aerodrome sketch will show the location and dimensions of the EMAS beds. In the example below, the EMAS bed is shown as an outlined box with diagonal lines running through it. The dimensions are provided in feet. 

Engineered Material Arresting Systems - depiction on an aerodrome sketch

EMAS depiction on an aerodrome sketch

9.1.3 Pilot Considerations for Engagement

Prior to using a runway, pilots should be aware of the presence of an EMAS bed. Pilots should review the aerodrome sketch and other aerodrome information to determine if the runway that they will be using is equipped with an EMAS.

During the take-off or landing phase, if a pilot determines that the aeroplane will exit the runway end and enter the EMAS, the following procedure should be followed: 

(a)  continue to follow rejected-takeoff procedures or, if landing, maximum-braking procedures outlined in the aircraft flight manual, regardless of aeroplane speed upon exiting the runway;

(b) continue straight ahead—do not veer left or right. Having all of the aeroplane’s landing gear enter the bed will maximize the EMAS’s stopping capability. Veering to the side may result in the aeroplane missing the bed altogether or having only one set of wheels enter the bed with reduced  effectiveness. The quality of deceleration will be best within the confines of the bed. The further the aeroplane travels into the bed, and into deeper concrete, the greater the deceleration;

(c)  do not take any action—the arrester bed is a passive system, similar to other traditional arresting systems such as cables, chains and aircraft netting;

(d) do not attempt to taxi or otherwise move the aeroplane once stopped;

(e)  use standard aircraft emergency ground egress procedures, should an emergency egress be required. Where the surface of the bed has been breached, the loose material will crush under foot. During egress, it is important to note that the two sides and the back of the arrester bed have continuous steps built in to help provide easy access for responding ARFF vehicles and to enable passengers to safely step off the bed; and

(f) use slides or aircraft stairs to deplane passengers after an EMAS arrestment as the EMAS bed will not provide a stable base for the air stairs.

9.2 Military Aircraft Arresting Systems

9.2.1 Background

Some civil airports and military aerodromes are equipped with aircraft arresting systems. An aircraft arresting system usually consists of two sets of gear, called energy absorbers, with one located on each side of the runway, normally approximately 460 m from the threshold. These energy absorbers are interconnected by an arrester cable, which is attached to a nylon tape that is wound onto a tape storage drum (reel) on each energy absorber. In order to locate the energy absorbers away from the edge of the runway, runway edge sheaves are located next to the runway edge. The runway edge sheaves act as a guide (pulley) for the tape and have sloped sides to permit an aircraft to roll over them.

When the tailhook of a fighter aircraft engages the cable, the tape storage drums start to turn. The energy absorbers apply a braking force to the storage drums, which in turn slows the aircraft and brings it to a stop. 

9.2.2 Markings

For identification, yellow circles are painted across the runway at the location of the aircraft arrester cable. A lighted sign with a yellow circle beside the runway marks the location during darkness.

9.2.3 Operations

At civil airports, civil aeroplane operations will not be permitted while the arrester cable is deployed across the runway. At military aerodromes, civil aeroplane operations may be permitted with the arrester cable deployed across the runway.

9.2.4 Damage Hazards

(a)  Cables: Pilots are advised to avoid crossing the aircraft arrester cable at speeds in excess of 10 mph, as a wave action may develop in the cable, which could damage the aircraft. This is particularly important for nose-wheel aircraft having minimal propeller or undercarriage-door clearance, or wheel fairings. Tail-wheel aircraft may also sustain damage if the tail wheel engages the cable.

(b) Runway edge sheaves: The runway edge sheaves are located next to the runway edge, on the runway shoulder, and they are above grade. The two sides perpendicular to the runway are sloped, but the other two sides, parallel to the runway, are vertical. The runway edge sheaves are not frangible and may cause damage to an aeroplane that contacts or rolls over one.

(c) Energy absorbers: The energy absorbers are normally located beside the graded area of the runway strip (at a distance greater than 61 m from the runway centreline). The energy absorbers are not frangible and will cause damage to an aeroplane that contacts one.

9.2.5 Information for Pilots

Pilots will normally be advised of the status of the arrester cable through ATIS or by ATC. The existence of an aircraft arresting system should be included in the runway data section of the CFS. The location of an aircraft arresting system should also be depicted on the aerodrome sketch.

Date modified:
2012-03-16