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Beyond the Runway End Safety Area
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Description
The consequences of many runway excursions, especially overruns, are made much more serious because the aircraft end up beyond the actual or nominal confines of the ICAO-defined Runway End Safety Area (RESA) and is catastrophically damaged because of major obstructions or terrain changes encountered soon after this protected area has been exceeded. Suddenly down-sloping terrain and low but substantial ground obstructions, which are of no concern to aircraft in flight, may take on considerable significance in determining the damage to an aircraft following a major overrun. The example of the Air France Airbus 340-300: [[1]] which ended up in a ravine at Toronto in 2005 illustrates this well.
Under ICAO SARPs, the Recommended extent of a RESA is considerably greater than the concomitant Requirement for one. However, the context for the consideration of what may be just beyond a RESA is that worldwide, and even in the USA, there are still large numbers of runways used by air carrier aircraft which do not yet have even the ICAO required RESA or satisfy the more stringent ICAO Recommended Practice or meet the equivalent (for overrun purposes) FAA ‘Standard’. State AIPs do not always include specific reference to the extent of RESA provision.
The RESA for some runways is surrounded by such dangerous features, usually on the runway extended centreline, that it might be considered that a raised prior awareness of flight crew of those consequences might have some effect on their subsequent focus on the final decision to make or complete a landing on such runways rather than initiate a go around including ones commenced as Rejected Landings. Similar reasoning applies to any decision to attempt a Rejected Take Off from a speed above V1. There appears to be some circumstantial evidence that it is flight crew who do not have sufficiently detailed personal knowledge of significant terrain or obstacle challenge beyond the immediate confines of a runway who are more likely to be involved in overruns which lead to major airframe structural damage.
Although Aerodrome Obstacle and Precision Approach Terrain Charts published in the AD section of State AIPs can identify notable terrain changes, this information is not routinely transcribed to the documentation available to Flight Crew unless it refers to terrain awareness which is relevant to safety in flight. In the case of notable non-terrain ground obstructions, these will only be recorded in an AIP - and therefore capable of transcription to flight crew documentation - where they are relevant to safety in flight.
It should be noted that the safety case for an EMAS has generally been made as a substitutes for a fully-established RESA. Any application of EMAS to reducing the risk of occasional overrun on take off or overrun on landing which extends beyond RESA must be regarded as at best problematic in the absence of any studies to define an appropriate lateral extent given at least some tendency to increasing divergence from the runway centreline as distance from a runway end increases.
Some UK Examples of Sudden Terrain Change beyond defined RESAs
The following are examples of sudden down-sloping terrain change beyond the existing RESA provision at three ICAO Annex 14 Code 3/4 runways used regularly by air carrier and other aircraft in the UK. The choice of UK examples should not be taken to imply anything more than illustrative convenience.
- EGGD Bristol UK Runway 27
At 60 metres from the end of the runway i.e. at the end of the Runway Strip, the terrain suddenly begins to drop steeply at a gradient of around 14%, continuing at a similar gradient for over 150 feet vertically. This is evident from the AIP Obstacle Chart
- EGJJ Jersey Channel Islands Runway 27
At approximately 100 metres from the stop end of this runway, there is a sudden and continuous drop in terrain of about 200 feet. This is evident from the AIP Obstacle Chart
- EGGW London Luton UK Runway 26
The terrain beyond the stop end of this runway initially slopes gently downwards at a gradient of about 3% for about 225 metres; the downward slope then increases to about 5% for a further 115 metres at which point an almost sheer drop of over 50 feet suddenly occurs. This is evident from the AIP Obstacle Chart and in slightly more detail on the Precision Approach Terrain Chart for Runway 08
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Further Reading
- See SKYbrary "Before you fly there" entires on Madiera Funchal (LPMA)