Airbus 380 loses engine, goes 5000 miles
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I don't think there's been a single case of a failure of ETOPS basic principles - i.e. a second engine failure - unless you count Air Transat Flight 236 - Wikipedia, the free encyclopedia.
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(xx)quad vs (xx)twin and "the next failure"
This value of xx should be less when there are ETOPS ratings and procedures involved.
Either environmental or common-servicing-error reasons could also come into play to make two failures on a quad more likely than just xx-squared.
When discussing this it might be better to consider not the number of accidents due to 3/4 or 1/2 of the engines working, or 2/4-or-2/2 failing, but rather to the incidences of these failures. From that, it might be clear whether we're overdue for the first accident to occur due to engine failures taking place a long way from safety in a twin.
Very roughly, with ~1000 ETOPS flights per day, and a few reported failures per year, it seems that ~1:100,000 flights have failures, and so a double failure might only be expected every ~10,000 years. If this is valid, then the current practice should be safe enough.
Either environmental or common-servicing-error reasons could also come into play to make two failures on a quad more likely than just xx-squared.
When discussing this it might be better to consider not the number of accidents due to 3/4 or 1/2 of the engines working, or 2/4-or-2/2 failing, but rather to the incidences of these failures. From that, it might be clear whether we're overdue for the first accident to occur due to engine failures taking place a long way from safety in a twin.
Very roughly, with ~1000 ETOPS flights per day, and a few reported failures per year, it seems that ~1:100,000 flights have failures, and so a double failure might only be expected every ~10,000 years. If this is valid, then the current practice should be safe enough.
Last edited by awblain; 4th Jan 2014 at 19:58.
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Even a glider can fly 
It depends....
A quad on one engine will probably have problems maintaining altitude depending on weight. But it will have a better chance of getting to a suitable landing site than a twin on none.
It depends....
A quad on one engine will probably have problems maintaining altitude depending on weight. But it will have a better chance of getting to a suitable landing site than a twin on none.
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Oh it can fly on *none* - see Gimli, and the quad-flameout in a volcalic ash cloud - but it will certainly be flying downwards. The rate-of-descent is what matters, and having one working donkey will certainly help in that regard.
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Yes, a quad can fly on one, but only in a shallow glide. Can even fly on none if needs be!
https://en.wikipedia.org/wiki/British_Airways_Flight_9
Gimli was a twin, btw
https://en.wikipedia.org/wiki/British_Airways_Flight_9
Gimli was a twin, btw
Last edited by Super VC-10; 4th Jan 2014 at 18:57. Reason: Note re Gimli
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Is that the one Lord King tried to buy?
(when asked, with all the twins coming into service, why BA was still buying 4-engined aircraft, he supposedly responded with "because they don't make them with five!")
(when asked, with all the twins coming into service, why BA was still buying 4-engined aircraft, he supposedly responded with "because they don't make them with five!")
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Part of the risk analysis of the 4 engine argument is a conservative assessment of the unknown. Zero risk is unattainable. On your remaining engines you still have wear out, infant mortality and random failure mode. When you mentioned lies and stratistics HDRW, I laughed when I also recall one of the models most commonly used in deciding on chances of failure of 4, 3, 2, 1 is the Monte Carlo Simulation (named after the gambling resort).
Perhaps the 'per flight' risk in the subject of this discussion was calculated as being low and that is why they decided to 'push on'. The data and engineering judgement so far (EK this incident of push on and SQ return) indicates there is not yet a consistent set of ground rules.
Perhaps the 'per flight' risk in the subject of this discussion was calculated as being low and that is why they decided to 'push on'. The data and engineering judgement so far (EK this incident of push on and SQ return) indicates there is not yet a consistent set of ground rules.
Perhaps the 'per flight' risk in the subject of this discussion was calculated as being low and that is why they decided to 'push on'. The data and engineering judgement so far (EK this incident of push on and SQ return) indicates there is not yet a consistent set of ground rules.
Too many what-ifs that are best handled today by pilots considering their resources both on-the-ground and in-the air.
then just to prepare for deep thinking arguments, why do we need an EROPs rule ? Has it saved anything ?
As you might suspect I see any diversion or air-turn-back as an increased risk as well as continuing.
ETOPS was perused by both Boeing and Scarebus so they could sell big twins to airlines to operate the Atlantic and Pacific more economically, with the comparable safety to the quads they replaced.
That didn't last long but, then again, neither did the A340!
Who can forget the A340 demonstrator at various airshows with "FOUR ENGINES FOR LONG HAUL" scrawled along the belt line in 3 metre high letters!!
Well until they bought their A330s.
losing engines....
Airbus 380 loses engine, goes 5000 miles.
Airbus 380 loses 2 engines, goes 10,000 miles.
Airbus 380 loses 3 engines, goes 15,000 miles.
Airbus 380 loses 4 engines, goes 20,000 miles.
DoT
Airbus 380 loses 2 engines, goes 10,000 miles.
Airbus 380 loses 3 engines, goes 15,000 miles.
Airbus 380 loses 4 engines, goes 20,000 miles.
DoT
