Why does CASA allow twin engine ETOPS operation at all?
 

I have recently heard a story about an aeronautical engineer who will not fly on the long trans-oceanic routes in anything less than a Boeing 747 or an Airbus A380. This person claims the reason is safety, and that a twin engine airline jet of similar manufacturing date (and therefore safety features) will never be as safe as a four engine aircraft.

He claims the whole ETOPS system is simply based on probability, and that one day, a twin engine aircraft will end up in the drink.

This person claims the safety difference is very small, but it is there nevertheless.

If this is so, how does CASA justify Part 9A of the Civil Aviation Act, which says that the number one priority shall be safety. In this case, it looks as if the number one priority is moving more passengers at a lower cost.

I would like to know what others comments are on this – especially those who have an aeronautical safety qualification and understand the risk matrix.

Presumably if the twin engine planes were as “safe” there would be no reason for ETOPS restrictions.

His logic is sound. It’s just that his perception of the consequences means that he vastly over-estimates the probabilities of a ditching caused by loss of both engines. The give-away would be if he’s prepared to drive a car on the highway.

A four-engined jet could end up in the drink one day, too. B747 + Mount Pinatubo = quadruple engine failure.

I don’t believe there is any evidence that he has over estimated the risk.

Just that the risk is higher in the twin.

So why does CASA allow?

So how many twin engine aircraft have been lost due to only having two engines? How does the risk analysis change if you compare an older generation four engine aircraft that is poorly maintained and flown by poorly trained crew to a modern two engine type with good maintenance history and well trained crew? Yes, ETOPs is based on probability, but isn't any safety system? If we were to try to eliminate all risk, regardless of cost, wouldn't air travel become unaffordable? I think a rather outspoken former Chairman of the CAA made this very point about 'affordable safety'. ;)

Go away...

That’s why I said he compared similar generation aircraft.

Headmaster. So you are saying in some cases CASA puts affordability in front of safety? How does that comply with 9a?

Well tricky dicky, I can see the angle you’re going for here. Using this to leverage something else.

However, provided the risk has been identified and the systems are in place to mitigate it, safety has been compiled with.

Hence the approvals, inspections, training and cost involved in ETOPS twins.

As much as I love the 747, the modern twin is leagues ahead in terms of design, system reliability and safety.

You can’t even start the apu inflight in the 747.

Having Class C airspace everywhere would be safer too, wouldn’t it?

Lancer. Yes. But the reason CASA does not require class C everywhere is that they have put affordability in front of safety.

So why live a lie with 9a ?

Green. No nothing tricky. What’s wrong with the truth? Or is that why you post anonymously when you don’t have to?

Do you benefit when finite safety resources are mis allocated?

Why not mandate 8 engined aircraft? Where do you stop?

You seem to be trying to solve a problem that doesn’t exist. How often has a dual engine failure on an ETOPS aircraft caused an accident?

:ok:...........

It’s clear that with GA CASA often quotes 9a as the reason they have to put “ safety” in front of cost.

Clearly not consistent. Imagine having to live a lie.

I dare one of you to answer the key point I put in post 1!

Wishy. Don’t you like the hypocrisy being exposed?

Roger Bacon
Flight International
(Many many years ago)

CC

I think the data speaks for itself. Millions of ETOPS hours flown with no defineable risk increase. Additionally ETOPS is dead and gone, it is now EDTO, where much more than just engine failure is considered, and in those areas 4 eng aircraft have zero safety advantage over a modern twin. Further if Australia was to go alone against the globally accepted ICAO EDTO standard, both Australian International airlines would become a footnote in the history books within a year as they became unable to compete against every other airline flying big twins.

That race has been run and won.

The assertion that CASA put cost ahead of safety is a totally different issue and one that I think is beyond doubt, but you will need to come up with a better argument than ETOPS/EDTO.

Dick,

You can takeoff from Sydney bound for Perth direct in a twin with a non EDTO approved aircraft that has to stay within 60 mins of Adequate Aerodromes. There is no requirement for these aerodromes to have good weather. They could all be fogged in. Assuming the flight time is 5 hours, you could be 2.5 hours from safety. Legally. And you could have MELs that further reduce the levels of safety (APU out etc).

However if you are EDTO approved twin aircraft (say 120 minute) you need to have weather conditions that are pretty good at your EDTO Alternate Aerodromes a maximum (equivalent) of 2 hours away. And you can't depart with certain systems/items inop lest they reduce the safety margins, you need to actively monitor the weather conditions when underway, AND all your critical systems have been inspected by different engineers in case they make the same mistake on both....

Ergo EDTO can be significantly safer than normal non EDTO flights. Should CASA ban non-EDTO flights?

Virgin sums it up perfectly

Which also shows the fallacy of your proposition Dick based on regulatory requirements and real world implementation.
FWIW I ferried a 767 from JFK to LGW many moons ago that was effectively missing the correct regulatory piece of paper that would have enabled us to dispatch ETOPs, as a result it was perfectly legal for us to fly via the blue spruce routes with not an airport between St Johns and Prestwick serious options due to a fairly standard North Atlantic winter.
I’ve spent 20 years flying 180-207 mins, I’m far more concerned about an onboard PED or IFE fire than an engine issue simply because that’s the reality.

Of course it is all based on probabilities etc, CASA is all about risk assessment and deciding what is an 'acceptable' level of safety. Why does your friend fly at all? After all it is a statistical certainty that at some point a passenger aircraft will crash and kill everyone on board, it has happened before and it will happen again so the only way to keep flying safe is for CASA to stop allowing aircraft to fly? How may all engine flameouts have there been, I can think of two off the top of my head:

1 - BA 747, all four out due to volcanic ASH
2 - A320, both out due to bird ingestion.

So on the basis of that it makes no difference if it is a 2 or 4 engine aircraft :-)

Just to be clear- this is Mr "Affordable safety" telling us we need to use less efficient aircraft in spite of decades and millions of hours of safe operation?

Does anyone know what has happened to Dick that he has gotten to this level of idiocy?

I think you’ll find Dick is trying to make precisely the opposite (and valid) point. Section 9A of the Civil Aviation Act means everything and nothing, when it suits. ETOPS and ETDO balance the infinitesimal probabilities of the double failure against the costs of mitigating the risks. If safety were indeed the most important consideration, it would always ‘override’ cost. And there would be no aviation.

Ollie Onion brings up a good point. Fuel starvation would be another thing to affect all your engines.

It would be interesting to put compile a list of events or factors which resulted in either a single (or particular) engine failure vs the failure of all engines... but that's an exercise for another day.

Jonee Helms was the administrator for the FAA back in the day (before ETOPS) apparently said he'd never allow it... things change, technology improves, etc.