GM1 ADR-DSN.C.236 Engineered Materials Arresting System (EMAS)

(a)Engineered materials:

(1)The materials are tailored to specific mechanical properties and are referred to as engineered materials.

(2)The engineered materials have to meet a force-deformation profile within limits which have been shown to assure uniform characteristics, and therefore, predictable response to an aircraft entering the EMAS.

(3)The engineered materials will crush under the landing gears of the aeroplane when it engages the EMAS. The crushing is an irreversible or partly irreversible process and the arresting performance of the system is proportional to the amount of energy that is dissipated.

(b)The compatibility of the EMAS with the specific meteorological and aerodrome conditions is ensured by using materials which:

(1)are water-resistant to the extent that the presence of water does not affect system performance;

(2)do not attract or are physically vulnerable to:

(i)vermin,

(ii)birds,

(iii)wildlife, or

(iv)other creatures to the greatest extent possible;

(3)do not support unintended plant growth with proper application of herbicides;

(4)exhibit constant strength and density characteristics during all climatic conditions within a temperature range that is appropriate for the local conditions;

(5)are resistant to deterioration as a result of:

(i)salt;

(ii)aircraft and runway de-icing and anti-icing fluids and solids;

(iii)aircraft fuels, hydraulic fluids, and lubricating oils;

(iv)ultraviolet;

(v)water;

(vi)freezing/thawing;

(vii)blowing sand and snow;

(viii)hail;

(viii)paint;

(ix)herbicides.

(c)Undershoot:

(1)An EMAS is not intended to reduce the risk of damage to an aeroplane undershooting the runway. However, the presence of an EMAS cannot increase the potential for damage in case of undershoot more than the risk that is associated with an undershoot in a RESA.

(2)Compliance with CS ADR-DSN.C.236 (c)(11) could be justified through experience of real cases of undershoot in an EMAS, flight simulator tests, other type of studies, or a combination of the three.

(d)An EMAS is a passive system which does not require any specific action or procedures by the flight crew. However, a basic knowledge of the systems by the crew is considered advantageous to prevent undesired evasive manoeuvres that could cause the aircraft to avoid entering the bed or system. The EMAS is designed to be entered preferably straight ahead with the unrestricted use of wheel brakes and/or thrust reversers. Additionally, the availability of an EMAS cannot be used for flight planning purposes, i.e., it cannot be included in the declared distances.

(e)Mechanical property:

(1)An EMAS is not intended to support vehicular traffic for maintenance or normal operating purposes.

(2)The EMAS needs to be capable of supporting personnel walking on it for the purposes of its own maintenance and co-located air navigation aids without causing any damage to its surface.

(3)Precaution needs to be taken during snow and ice removal to prevent damage to the EMAS bed.

(4)Light equipment for snow removal may be used in accordance with the manufacturer´s specification to avoid any damage to the surface.

(f)Setback distance:

(1)The setback distance is defined as the distance between the runway end or stopway, if provided, and the beginning of the EMAS.

(2)The setback distance will vary depending on the available area and the EMAS design.

(3)The calculation of the setback distance balances the risk objectives of:

(i)providing enough area for arresting purposes;

(ii)providing enough separation to protect the bed from jet blast;

(iii)providing separation from the threshold to reduce the probability of undershoot in the EMAS; and

(iv)decreasing the probability of aircraft overruns passing by one side of the EMAS due to lateral dispersion. The safety assessment determines the relevance of each risk objective, taking into account the operating particularities of the associated runway, including usage of the runway, types of approach, weather conditions, fleet, incidents and accidents, and any other particularity related with runway safety.

(4)To reduce the probability of an aircraft undershooting in an EMAS, it is recommended to provide a minimum setback distance of at least 60 m from the threshold or runway end. However, this separation may be reduced if a safety assessment determines that it is the best alternative for both overrun and undershoot protection.

(g)An EMAS normally includes steps and/or slopes at its end and both sides, but they are not considered functional for arresting purposes. Where possible, the functional width of the EMAS is to be maintained the same throughout the whole length of the system.

(h)Exit speed is defined as the speed of the nose gear of the aeroplane as it passes the runway end or stopway, if provided.

(i)The critical aircraft is defined as the aircraft that regularly uses the associated runway that imposes the greatest demand upon the EMAS.

(j)Design aircraft list refers to the combination of aircraft types which are/will be operating regularly on the runway. The critical aircraft is usually, but not always, the heaviest/largest aircraft that regularly uses the runway. The performance of an EMAS is dependent not only on aeroplane weight, but also on the landing gear configuration, tyre pressure, and centre of gravity. In general, the operational maximum take-off weight (operational MTOW) is used for the critical aircraft. However, there may be instances where less than the MTOW will require a longer EMAS. All parameters are to be considered in optimising the EMAS design. However, to the extent practicable, the EMAS design may consider both the aeroplane that imposes the greatest demand upon the EMAS and the range of aircraft expected to operate regularly on the runway. In some instances, a composite of design aircraft may be preferable to optimising the EMAS for a specific runway than a single critical aircraft. Other factors that are unique to a particular aerodrome, such as available RESA and air cargo operations, should also be considered in the final design.

(k)Testing: Testing is to be based either on passage of an actual aircraft, or a single wheel bearing an equivalent load through a test bed. The design will need to consider multiple aircraft parameters, including but not limited to allowable aircraft gear loads, gear configuration, tyre contact pressure, weight, centre of gravity, and speed.

[Issue: ADR-DSN/6]