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Statistically, when will a large twin engine jet end up in the drink?

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Statistically, when will a large twin engine jet end up in the drink?

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Old 3rd Jan 2019, 21:30
  #61 (permalink)  
 
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I'm sorry Dick, where in the replies that you have received does it clearly state that? What is the written evidence?

I understand your end game reference the Act but I don't really see evidence in this thread that supports your position.
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Old 3rd Jan 2019, 21:31
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Like so many safety issues we will only really know the statistical answer looking back.

The move to twin engines was paralleled by increased reliability of engines and redundancy of systems and more obsessive maintenance processes and the flight crews desire to arrive safely too on failure of engine #1. The sum of those factors is still being calculated

The Customer is a realist: They like cheap flights and if the chances of making it to a safe landing are increasing vs last time they don't care much about the reliability of the most reliable parts . . most are more scared of a nut-case fellow passenger
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Old 3rd Jan 2019, 23:09
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Originally Posted by Dick Smith View Post
It’s clear that the prime reason for the move from 4 engined to two engined is not to improve safety but to improve participation levels and airline profits- and it has clearly worked.

Thanks for all the written evidence I require to show that.

CASA is clearly not complying with “the lie” in the act!

One day the act act will be changed to reflect the truth.
And the agenda is revealed
Would you mind sharing some of the "written evidence" supporting your position that quads are more safe than twins? I haven't seen any - on this thread or anywhere else.
On the other hand, there is a whole bunch of data that says twins are safer than quads. For example (numbers as of 2016):
The most common quad in service over the last 30 years is the 747-400 - fatal hull loss rate 0.49 (the older -1/2/300 model 747s are quite a bit worse at 1.46)
By comparison, the aircraft that have largely replaced the 747 on the long over water routes are the 767, 777, and A330. Their fatal hull loss rates:
767 - 0.10
777 - 0.20
A330 - 0.21
All substantially better than 747-400. As are the hull lost rates for the 737NG, 757, and A320 series.
Granted, the A380 rate is currently zero - no fatal hull loss events -but it's a statistically small fleet, however the statistically larger 787 fleet is also at zero (as is the A350).
So I ask again, please share your data that proves twins are less safe? Or will you simply keep repeating your assertion and hope that if you repeat it enough times people will assume it's true?

Oh Squawk - you might want to know that resorting to personal insults is generally considered evidence you're loosing the debate.
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Old 3rd Jan 2019, 23:25
  #64 (permalink)  
 
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Originally Posted by Jetstream67 View Post
Like so many safety issues we will only really know the statistical answer looking back.

The move to twin engines was paralleled by increased reliability of engines and redundancy of systems and more obsessive maintenance processes and the flight crews desire to arrive safely too on failure of engine #1. The sum of those factors is still being calculated

The Customer is a realist: They like cheap flights and if the chances of making it to a safe landing are increasing vs last time they don't care much about the reliability of the most reliable parts . . most are more scared of a nut-case fellow passenger
Folks,
One thing I can say without doubt, because I was in the middle of it --- when EROPS (ETOPS/EDTO) was first established in Australia and NZ (and bear in mind no European nation allowed it for years after --- long range twins were "not safe") perhaps the statistics were not as sophisticated as now (after all, there was no huge body of statistics for big twins) but one thing is for certain!!

No supporters of the changes proposed, and those involved in the regulatory approvals (FAA, whatever CASA was then -CAA?, Boeing, P&W and GE, AIPA, QF etc.) considered big twins "safer" or "as safe" as a B747, but the risk of a multiple engine failure was ALARP- As Low As Reasonably Practicable, and that assessed residual risk was seen as acceptable.

Don't forget --- quite properly, in my opinion, many engine failures were excluded from the calculations --- fundamentally any engine failure not in the EROPS phase of the flight. Failures on takeoff, bird-strikes etc did not count.

Increased concern about hold fires and Class D compartments falling out of favour was years down the track, as were lithium batteries, and, if I recall correctly, the very first edition of AS/NZ 4360, Risk Management

Other system redundancies were carefully considered (the B767 has better electrical redundancy than the B747) --- but the "biggie" was engine failure) and aircraft modified compared to a non-ER B767, and it was all about the B757/767, because Airbus didn't want to know, because JAA/UK CAA etc., and all the European pilot unions said NO!!. ITS NOT SAFE!! I don't remember the exact timescale, but the A310, the first Airbus so certified was quite a few years after Boeing.

So Dick's basic proposition is correct, in the genesis of EROPS/ETOPS/EDTO, all accepted (whether it was right or wrong) that long range twins were not "as safe" as a three or four engine aircraft, but they were "safe enough" (my words)--- and "absolute safety", "safety is our first priority" and the present CASA selectively preferred interpretation of S.9A of the Act did not get a look-in.

And Dick's proposition that the Act should be amended, as agreed by Barnaby and Albo, as Minister and Shadow Minister, remains a necessary change, has been a necessary change since 1998, 20 years --- without which we will not see proper application of risk management principles across the board in aviation in Australia --- it will be confined to those with the commercial power.

Tootle pip!!

Last edited by LeadSled; 4th Jan 2019 at 03:56. Reason: typo and minor text amm.
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Old 3rd Jan 2019, 23:58
  #65 (permalink)  
 
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So Dick's basic proposition is correct, in the genesis of EROPS/ETOPS/EDTO, all accepted (whether it was right or wrong) that long range twins were not "as safe" as a three or four engine aircraft, but they were "safe enough" --- and "absolute safety", "safety is our first priority" and the present CASA selectively preferred interpretation of S.9A of the Act did not get a look-in.
Perhaps that was true 30 years ago in Australia, I'm not in a position to know. But I was involved in the development of EROPS/ETOPS rules with the FAA in that same time frame. No such provision was made about 'safe enough' - either it's safe (per the one in a billion requirement I posted earlier) - or it's not safe - in which case it's not certifiable. That some groups objected is immaterial - that's an emotional response, not a technical response (not unlike the two crew/three crew flight deck debate)
EROPS/ETOPS rules were developed using technical statistical methods - the same statistical methods used for showing every other critical system on the aircraft is safe. It's also used for an "Equivalent Level of Safety" (ELOS) - when a new design doesn't meet the letter of the regulation but meets the intent of the regulation the regulators can grant an ELOS finding (ELOS was heavily used when EICAS was incorporated to replace all those flight deck lights and dials - and was needed when Boeing incorporated the thrust reverser 3rd lock after Lauda - 25.939 says a deployment in flight must be controllable but with big fan engines that's no longer practical, so Boeing was able to obtain an ELOS by showing the 3rd lock was effective in making sure an in-flight deployment wouldn't happen).
Further, IIRC, while Qantas was an early adopter of EROPS (for flying over the Australian outback), Australia's initial EROPS rules were based on the already existing FAA EROPS rules - rules that had already shown to be just as safe as a quad.
Besides, this whole crusade overlooks a very basic fact. As per my earlier post, current ETOPS twins are statically meaningfully safer than the quads and tri-jets they replaced. By that metric, allowing ETOPS has actually made flying safer and hence saved lives.
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Old 4th Jan 2019, 01:38
  #66 (permalink)  
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That “ one in a billion” requirement sounds to me that the standard does not call for absolute safety.

It looks as as if there are compromises made for affordability reasons.

That is in in some cases CASA and regulators throughout the world put the ultimate cost of safety improvements as the most important consideration.

Just a fact of of life that is admitted in other countries and reflected in legislation.

But not in Canberra. They have “ safety” as the most important consideration- more important in all cases than cost.

Why they live this lie is behind me.

In in the meantime with the “one in a billion” parameter when is it likely that a twin will end up in the ocean?
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Old 4th Jan 2019, 02:20
  #67 (permalink)  
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I note this paragraph from the article “Engine-failure 777 busts ETOPS limit

“The FAA at present is working in co-operation with US industry body the Aviation Rulemaking Advisory Committee to draw up a new set of standards for long-range aircraft regardless of the number of engines they have, possibly taking modern twins into the 240min ETOPS range and beyond.”
It looks as if since then the rules are simply re-written to allow twin engine aircraft to be used on routes where it is obvious that a four engine aircraft of a similar production date and safety features would be safer.
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Old 4th Jan 2019, 02:36
  #68 (permalink)  
 
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Dick, the 180 minutes in the article you quote is a planning issue only - planned at up to 180 mins from an appropriate diversion field BUT the pilot in command does not need to fly at the speeds which are used to calculate that 180 minute distance.

So conceivably any number of aircraft schlepping across the Pacific today could quite easily take longer than their diversion time (be it 60, 120, 180, 240, 330, 370 minutes)

I note the A350 has been certified for ETOPS 370 - 6hrs and 10 minutes - but these distances are necessarily derived using a specific speed schedule against the necessary time, so there is no obligation on the crew to fly the speeds used to calculate the ETOPS range rings
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Old 4th Jan 2019, 02:47
  #69 (permalink)  
 
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Originally Posted by Dick Smith View Post
That “ one in a billion” requirement sounds to me that the standard does not call for absolute safety.

No, it is an acknowledgement that - in the real world - "absolute safety" is a myth. Absolute safety simply doesn't exist - particularly in a complex system such as a commercial jetliner.

Originally Posted by Dick Smith View Post
In in the meantime with the “one in a billion” parameter when is it likely that a twin will end up in the ocean?
Well, at least one 777 has in fact ended up in the ocean - MH370. Of course, based on what's currently known about MH370 the number of engines was immaterial.
As for the rest of your question, all it demonstrates is your lack of understanding of statistics.
BTW, still waiting for you to provide data to back up your claim that quads are safer than twins on long over water routes.
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Old 4th Jan 2019, 03:45
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Originally Posted by tdracer View Post
Further, IIRC, while Qantas was an early adopter of EROPS (for flying over the Australian outback), Australia's initial EROPS rules were based on the already existing FAA EROPS rules - rules that had already shown to be just as safe as a quad.
.
tdracer,
As you admitted, you were not involved in the development of the Australian (and NZ) rules, and it shows.

EROPS in Australia had nothing to do with the "outback', there was no shortage of places you could put a B767. ( or an early B737, A300 or.DC-9 --- none ever ER)

And everything to do with a network around the western Pacific and SE Asia.

AND, if you had any knowledge of those original AU rules (versus the FAA's, which were developed in an atmosphere of universal pilot union opposition, and resultant political lobbying, and luke warm, at best, FAA support) they were substantially different to the FAA original rules, that were "intended" to make trans-Atlantic EROPS operations as close to impossible as possible. And, if my memory serves me correctly, AU in operation before the US rules. Certainly, Qantas and Air New Zealand conducted something like 80% of EROPS operations in the first three or so years of the "new rules". --- refer the Boeing library.

And a roaring operational and commercial success it was!! Nice to be leader, and not followers, just occasionally. The only case similar I can thing of was FANS-1..

Just one example, AU v. FAA, that I remember --- at no stage did we have to plan for engine out depressurized 10,000 ft diversion in icing conditions. Our rules were really quite practical and common sense --- and said practical common sense had as much influence on the final rules as statistical justification.

And another example, the Captain in the AU rules ( unusual for Australia) had much greater freedom of action, once airborne, than under original FAA rules.

As a final comment, once you get to such low rates of adverse occurrences as the airlines now achieve, ALL occurrences are individual, one interpretation, valid in theory, is that there are not enough occurrences to draw statistically valid conclusions about failure patterns in (now) EDTO --- hence being able to certify a new type "out of the box". With most ICAO states close to the ICAO SARPS, the aircraft performance has developed to the degree that the now more restrictive (compared to AU original) rules have a very limited operational/commercial impact.

Tootle pip!!

PS: Are you aware that there are a number of risk levels used across the board in aviation regulation (except, generally speaking, in Australia) , not one single one to define "safe/unsafe", as you suggest?

Last edited by LeadSled; 5th Jan 2019 at 09:05. Reason: spelling
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Old 4th Jan 2019, 04:10
  #71 (permalink)  
 
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Originally Posted by Veruka Salt View Post
Dick,
Engine reliability is only part of the risk analysis. Cargo fire suppression, amongst other things, plays a part.
Cargo fire suppression is designed to meet ETOPS, not the other way around. Greater ETOPS range, add another bottle to be metered out in the extra hour.

Originally Posted by Veruka Salt View Post
Dick,
Originally Posted by Veruka Salt View Post
FYI the 4-eng aircraft in our company are required to comply with ETOPs rules beyond 180 mins flight time from an adequate airfield.
What do they call those operations since they are not ETOPS?

Originally Posted by Squawk7700 View Post
Because it’s being flogged and pushing along a bloody big aircraft on its own! Isn’t that to an extent, what happened to Wyalla?
That is hilarious. Post of the Year!

Originally Posted by Dick
With more and more EDTO throughout the world (literally millions of hours), statistically someone must have worked out when one of these aircraft is going to end up in the drink. That is, originally there is a single engine failure, and before it can get to the alternate and land , the other engine fails. I have recently been told that statistically we are over that time and the safety experts are wondering when such a disaster will happen.

It's already happened. Here's a list of many glide events.

Here's a specific list of ditchings. Not all are relevant but many are. Having had more than our share events, statistically we should be fine for another 173 years.
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Old 4th Jan 2019, 04:24
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PS: Are you aware that there are a number of risk levels used across the board in aviation regulation (except, generally speaking, in Australia) , not one single one to define "safe", as you suggest?
I presume you're referring to Minor, Major, Hazardous, and Catastrophic - with associated allowable probabilities of 10-3, 10-5, 10-7, and 10-9/hr, respectively. You are correct that 'safe' is not referred to in so many words, however it's commonly stated that if a system can meet the 10-9/requirement, then it's considered safe and you don't even need to address if the failure is Hazardous or Catastrophic.
The original FAA EROPS requirements were finalized in 1985 - and were soon used across the north Atlantic (granted, it's possible to fly across the north Atlantic using a 60 minute diversion using less than optimal routing - some operators chose to remain with 60 minutes or a strange pre-EROPS 90 minute 'exception' rather than jump through the hoops for full EROPS). I certainly don't remember the early rules as making " trans-Atlantic EROPS operations as close to impossible as possible" - although they were rather restrictive.
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Old 4th Jan 2019, 04:37
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Originally Posted by Eclan View Post
What do they call those operations since they are not ETOPS?
Extended Diversion Time Operations - EDTO. EDTO applies to all passenger aircraft - including quads and tri-jets - starting roughly five years ago (cargo quads and tri-jets are exempted from EDTO, cargo twins do need to meet it).
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Old 4th Jan 2019, 10:30
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As mentioned by tdracer, since 2015 in our area of the world at least, ETOPS basically doesn't exist, and is now EDTO. The CASA CAAP about it all is listed below.

EDTO - Civil Aviation Safety Authority

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