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90m RESA just before a cliff, does it make sense?

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90m RESA just before a cliff, does it make sense?

Old 31st Jan 2013, 22:50
  #1 (permalink)  
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Join Date: Jan 2013
Location: London
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90m RESA just before a cliff, does it make sense?

This is my first post. I am not a pilot but a junior engineer. I would like to gather some opinions regarding the RESAs.

Close to where I live there is this airport ( A Coruna, ICAOís code: LECO, IATA: LCG AD - Aerodromes - Navegacion Aerea - Aena.es - Spanish airports and airspace )
with a 1940 meters runway (so code number 4 according to ICAO), which has around 10,000 operations per year and serves around one million passengers per year. On each side of the runway it has the 60m strip plus 90m RESA, so the bare minimum required by ICAO.

The shocking thing is that it is on a plateau, so just after the end of the RESAs there are vertical cliffs of up to 60ft.There are no EMAS or similar system, the RESAs have a downward slope of around 5% which makes them even less effective and due to weather conditions the it often operates in wet conditions and even with a bit of tailwind (there are not instrument procedures to land on runway 03 or take off from runway 21).

My first question is, even if the airport satisfies the Annex 14, isnít this situation a bit dangerous? I mean, surely the Annex 14 does not say anything, for example, about nuclear reactors, but I would not put a nuclear power plant 500 meters after the end of a runway.
I find even more surprising the fact that the runway and strip are going to be extended 400m to allow the operation of larger aircrafts (even if there is already a nearby airport, SCQ, with some 3200m runway), but the RESAs will still be kept at the bare minimum.

To me this sounds a bit crazy: extending the runway by 400m would allow the displacement of the thresholds 150m from the ends and it would still get
TORA=2190 TODA=2490 ASDA=2190 LDA=2040
which would put leave cliffs at 300m from the end of the thresholds and would still be an improvement over the current situation ( TORA=1940 TODA=2090 ASDA=1940 LDA=1940).
What are your views: am I being too picky, is this crazy or somewhere in between (not ideal, but acceptable)?

EnxAero is offline  
Old 1st Feb 2013, 07:37
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So it is ICAO compliant. Remember a RESA is there to reduce the risk of damage to an aeroplane undershooting or overrunning the runway, so what lies beyond or outside this area is irrelevant for an aircraft that overshoots or under-runs and stops on the RESA.

Does it make sense? Up to a point.

There are people and organisations that prefer to talk about de-lethalising the area around a runway so that an aircraft running off the runway will not kill people (even though the aircraft may ultimately be destroyed). But the current standards do not do this. But because there is a lot of pressure to comply with the rules you do get some daft outcomes - see the runway at Funchal, for example.

As for nuclear power plants and the like, aviation standards are about keeping aircraft and flying safe - there are other standards that keep nuclear power plants safe. Following your logic, it might be better to ban schools from being built near an airport because almost every time an aircraft comes to grief, the pilot has to valiantly steer the aircraft away from an inconveniently located school.

In theory, everything aviation should now be doing safety management. In very simple terms - although those who try to make common sense into SMS science may disagree - this means that someone building a runway should first apply the relevant standards and then say, 'OK, could we do anything to make it safe enough to use'. It is at this point that someone should say, 'Well, if an aircraft over-runs it will drop over the edge of the cliff. Maybe we need an arrestor system of some sort....'.
Old 13th Feb 2013, 23:17
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Yes, we agree in that a runway can be ICAO compliant and still the design might be daft.

In this particular case, an overrun of 149m would probably mean some damage to the undercarriage, while an overrun of 151m would probably mean complete destruction of the aircraft with no survivors.

So what I am trying to grasp is, in practical terms and taking into consideration the circumstances, whether 150m is "far enough" or "too close to the end of the runway".

I guess for the average passenger is probably not a big concern, because the probabilities of a fatal accident are still low, but for a company operating say 1,000 or 2,000 flights a year from there could be more affected (for instance if the probability of an overrun >150m overrun were 1/2,000,000 there would be a 1/1,000 chance of losing a plane per year only in that airport).

Any views or gut feeling?
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Old 14th Feb 2013, 09:26
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Sir George Cayley
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Hi EnxAero,

I think you raise a valid point for discussion especially after the Moscow plane crash and the motorway barrier beyond their RESA.

90m is a minimum requirement and 240m a recommendation so compelling an airport to provide the full 300m (60 + 240) is unlikely. Until after the accident

Using Street View one can see the aircraft carrier type runway perched on top of the hill and the precipitous drop at each end. The area before Rwy 21 looks somewhat bizarre with netting and lots of green poles; what's that all about? Wish I could post a photo to show everyone.

When an airport looks to lengthen their runway to more than 2100m that suggests they hope for bigger a/c to serve longer route. (natch) It follows that a/c mass and energy increase putting more stress on safety areas.

It seems obvious that the laws of physics will win but I wonder if all airport directors fully appreciate the potential erosion of safety margins.

Maybe you could keep an eye on this airport and update us on any developments. Thanks for your post.
Old 15th Feb 2013, 23:25
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Sir George Cayley,

They are indeed hoping to get longer distance flights and even trans-oceanic. I do not know how realistic that is, since SCQ is only 65km from there, but has only managed to attract one flight to Turkey, even if it has a 3200m runway.

I believe the pictures in Street View are old. I think the green poles before Rwy 21 are now part of the structure that supports the artificial reference surface for the radio-altimeter, which begins 400m before the threshold.
This can be seen in the Precision Approach Terrain Chart from the link below
AD - Aerodromes - Navegacion Aerea - Aena.es - Spanish airports and airspace

I am now working abroad, but I will try to take some pictures next time I am around there.
EnxAero is offline  
Old 16th Feb 2013, 11:55
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Sir George Cayley,

I think they are indeed hoping to get longer routes, and even transoceanic flights. I do not know how realistic that is, since SCQ is only 65km from there and they only have one "long" flight (assuming a 2,000 miles flight to Turkey can be considered long). And SCQ has already a 3200m runway.

I think the photos in Street View are a bit old. I believe the green poles are now part of the structure supporting the artificial reference surface for the radioaltimeter, which starts 400m before the threshold or rwy 21 and prevents a sudden drop of 60ft in the RA when passing over the cliff. The details can be seen in the Precision Approach Terrain Chart in AD - Aerodromes - Navegacion Aerea - Aena.es - Spanish airports and airspace

I am now working abroad, but I will try to take some pictures next time I am over there.
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Old 27th Feb 2013, 23:37
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Join Date: Dec 2007
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Runway standards

A runway used by a C172 and is, say 2000 ft long will suffice at low altitudes, however, this runway will not accomodate a heavy passenger aircraft and, certainly not, when the brakes or tire friction fail. So it boils down to common sense used by the pilots, although this is questionable as the Air France runway overrun in Toronto had more than enough runway length, but the pilot decided to stay on the deck even after he had landed long because of an (non-stabilized approach) overspeed situation.
Having a cliff at the end of a relatively short runway overrun puts weight and performance restrictions on aircraft and, again, the pilot has to use common sense in rejecting its use when he knows that a slight miscalculation of runway friction or temp/alt effect on engine performance is highly probable. This can all be determined and decided long before actually using the runway.
Experienced pilots who value their lifes will make the right decisions.
Yankee Whisky is offline  
Old 14th Jun 2014, 18:46
  #8 (permalink)  
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It's been more than a year, but as I promised these are two pics of the area.

Note that only the top 12 m of the lights are frangible, even if they are less than 300 m from the threshold. Not that matters at all, since the radioaltimer reference surface is not frangible at all (I guess this does not comply with 9.9.5), but in any case the main issue is the concrete wall, 150 m before the threshold.
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