ETOPS and the ETP
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I operate ETOPS/EDTO a couple of times per month, so I have a genuine interest in this topic.
Once upon a time, twin engine high capacity turbine aircraft had to be operated within 60 minutes of an adequate airport.
In case one engine failed, the reliability of the remaining engine was seen to be no more than 60 minutes, based on statistics and the probability of a further in- flight shutdown. (My interpretation and understanding.)
That was as far as the authorities allowed us to go.
Even today, if we depart an airport that is closed for arrivals, we still need to provide a take-off alternate within 60 minutes flight time of departure at single engine cruise speed in case we have an engine failure during the departure. Why is this?
Safety of aircraft, safety of the passengers, further technical difficulties etc.
Then, we wanted to go further, so straighter tracks were planned taking us greater than 60 minutes from an adequate airport, and ETOPS/EDTO evolved.
Still based on statistics for an in flight- shutdown, 90, 120, 150, 180, 240 minutes from an adequate airport was granted, based on the regulators approval for such operations.
Often during ETOPS/EDTO, there are other available adequate airports closer than the ETOPS pair that can be considered. That is why my ETP pair is always the 2 closest available airports, in case something unforeseen should happen. ETOPS/EDTO just defines the area of operation. It doesn't dictate where you must go within the area of operation.
So, PKMJ to PHNL. It's great circle distance is 1981 NM. No other airports available. An offset ETP will be at slightly greater or much greater than half great circle distance (990 NM). It really doesn't matter as long as we don't fly more than 3 hours in either direction. Otherwise, we are flying contrary to our aviation authorities ETOPS/EDTO regulations. Refer CAO 82.0 appendices 4 and 5, EDTO.
United Airlines fly to Majuro 3 days a week in a B737-800, so the airport is more than capable of handling an A330. RNAV approach both runways. As good as an ILS. Would we have any qualms about performing the 34 RNAV approach at YMML? Probably not I'm guessing. Given 2 hours notice, how unlikely would it be that the airport, stipulated for such eventualities, would not be available for us to use? Forget PAX comfort for the minute. We are up to 3 hours over water from the closest available airport, now on 1 engine. Passenger and aircraft safety are the only things that matter.
At what point do we say continue to Honolulu. 3 hours before Honolulu? definitely. At 3.5 hours before Honolulu? most likely. Any longer than 3.5 hours when an adequate airport, let's assume with ok WX is available, at less flying time? Where do we draw the line?
It would depend on the nature of the problem, where the problem occurred, whether you continued toward destination while trying to sort it out, (should you turn towards the closest airport while trying to sort it out?), the possibility of further problems and where all this left you reference to either airport once the final decision was made.
Either way, the flight time remaining needs to be less than 3 hours on single engine.
It is all about passenger and aircraft safety within the regulations. Operator convenience and PAX comfort have nothing to do with it.
Once upon a time, twin engine high capacity turbine aircraft had to be operated within 60 minutes of an adequate airport.
In case one engine failed, the reliability of the remaining engine was seen to be no more than 60 minutes, based on statistics and the probability of a further in- flight shutdown. (My interpretation and understanding.)
That was as far as the authorities allowed us to go.
Even today, if we depart an airport that is closed for arrivals, we still need to provide a take-off alternate within 60 minutes flight time of departure at single engine cruise speed in case we have an engine failure during the departure. Why is this?
Safety of aircraft, safety of the passengers, further technical difficulties etc.
Then, we wanted to go further, so straighter tracks were planned taking us greater than 60 minutes from an adequate airport, and ETOPS/EDTO evolved.
Still based on statistics for an in flight- shutdown, 90, 120, 150, 180, 240 minutes from an adequate airport was granted, based on the regulators approval for such operations.
Often during ETOPS/EDTO, there are other available adequate airports closer than the ETOPS pair that can be considered. That is why my ETP pair is always the 2 closest available airports, in case something unforeseen should happen. ETOPS/EDTO just defines the area of operation. It doesn't dictate where you must go within the area of operation.
So, PKMJ to PHNL. It's great circle distance is 1981 NM. No other airports available. An offset ETP will be at slightly greater or much greater than half great circle distance (990 NM). It really doesn't matter as long as we don't fly more than 3 hours in either direction. Otherwise, we are flying contrary to our aviation authorities ETOPS/EDTO regulations. Refer CAO 82.0 appendices 4 and 5, EDTO.
United Airlines fly to Majuro 3 days a week in a B737-800, so the airport is more than capable of handling an A330. RNAV approach both runways. As good as an ILS. Would we have any qualms about performing the 34 RNAV approach at YMML? Probably not I'm guessing. Given 2 hours notice, how unlikely would it be that the airport, stipulated for such eventualities, would not be available for us to use? Forget PAX comfort for the minute. We are up to 3 hours over water from the closest available airport, now on 1 engine. Passenger and aircraft safety are the only things that matter.
At what point do we say continue to Honolulu. 3 hours before Honolulu? definitely. At 3.5 hours before Honolulu? most likely. Any longer than 3.5 hours when an adequate airport, let's assume with ok WX is available, at less flying time? Where do we draw the line?
It would depend on the nature of the problem, where the problem occurred, whether you continued toward destination while trying to sort it out, (should you turn towards the closest airport while trying to sort it out?), the possibility of further problems and where all this left you reference to either airport once the final decision was made.
Either way, the flight time remaining needs to be less than 3 hours on single engine.
It is all about passenger and aircraft safety within the regulations. Operator convenience and PAX comfort have nothing to do with it.
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Even today, if we depart an airport that is closed for arrivals, we still need to provide a take-off alternate within 60 minutes flight time of departure at single engine cruise speed in case we have an engine failure during the departure
It really doesn't matter as long as we don't fly more than 3 hours in either direction. Otherwise, we are flying contrary to our aviation authorities ETOPS/EDTO regulations
Either way, the flight time remaining needs to be less than 3 hours on single engine.
what mob do you fly for ekolbregit? sounds like a few differences there
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This situation and thinking about it was first mooted on PPRuNe more than 10 years ago.
A very similar incident with a heavy, trans Pacific twin and an engine going sub idle.
The surprise, discussed as part of the wash up afterwards, was the 3 tonne hole in the fuel plan options they thought they had with a useless engine plodding away alongside them as a very large, thirsty APU.
Rob
A very similar incident with a heavy, trans Pacific twin and an engine going sub idle.
The surprise, discussed as part of the wash up afterwards, was the 3 tonne hole in the fuel plan options they thought they had with a useless engine plodding away alongside them as a very large, thirsty APU.
Rob
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I'm happy to be wrong. I just referenced CAO 82.0. Perhaps CAO 26 trumps COA 82. I'm not sure.
Please show me the references.
When an ETOPS airport becomes unavailable during cruise, we always had 3 options: turn around, divert to remain in ETOPS coverage of an other available airport or land. Of course with 2 engines operating, and engine failure probabilities being low, we would most probably keep going if time intervals were reasonably insignificant.
Either way, here we are talking about a specific airport pair, both available, and what is or is not considered to be an acceptable risk.
Like I said, I deal with this a couple of times a month and my licence is on the line every time.
Perhaps I'm about to be re educated.
Please show me the references.
When an ETOPS airport becomes unavailable during cruise, we always had 3 options: turn around, divert to remain in ETOPS coverage of an other available airport or land. Of course with 2 engines operating, and engine failure probabilities being low, we would most probably keep going if time intervals were reasonably insignificant.
Either way, here we are talking about a specific airport pair, both available, and what is or is not considered to be an acceptable risk.
Like I said, I deal with this a couple of times a month and my licence is on the line every time.
Perhaps I'm about to be re educated.
There is no time limit on a takeoff alternate in oz - unless your company mandates it. You just have to get somewhere else in any timeframe (less than max endurance!). Most other sensible states follow ICAO Annex 6 stating a 60 minute takeoff alternate if dept weather is cr@p.
If an EDTO airport went out in cruise - and you were already past your EEP, what states you have to divert to remain within three hours of another EDTO alternate? Why couldn't you just keep going?
And your EDTO area is predetermined by distance - not time. This is a common misconception. It is the distance travelled in a time (eg 180mins) at a predetermined speed and weight. For arguments sake, let's assume your EDTO threshold is 1300nm @ 180 mins. You can now fly up to 1300nm from your nominated EDTO aerodrome, irrespective of winds. If then you had a 100kt headwind for the divert, you'd end up taking 234 mins to get there. Totally legal under the regulations. Of course your EDTO xtra fuel on your plan would be significant.
If an EDTO airport went out in cruise - and you were already past your EEP, what states you have to divert to remain within three hours of another EDTO alternate? Why couldn't you just keep going?
And your EDTO area is predetermined by distance - not time. This is a common misconception. It is the distance travelled in a time (eg 180mins) at a predetermined speed and weight. For arguments sake, let's assume your EDTO threshold is 1300nm @ 180 mins. You can now fly up to 1300nm from your nominated EDTO aerodrome, irrespective of winds. If then you had a 100kt headwind for the divert, you'd end up taking 234 mins to get there. Totally legal under the regulations. Of course your EDTO xtra fuel on your plan would be significant.
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Compressor Stall.
In my first post I mentioned the take-off alternate was required if the departure airport was closed to arrivals. Fair enough regarding Oz. I've not worked there for some time. It was the general principle of a take-off alternate, Australia excluded.
In the last post I apologise for my lack of clarity. I said "Of course with 2 engines operating, and engine failure probabilities being low, we would most probably keep going if time intervals were reasonably insignificant". I meant being already inside the ETOPS threshold for the airport that became unavailable.
With regard to your last point, you may well be correct. ETOPS defines the total area of operation. One may well be able to choose one's preferred airport. But I wouldn't wish to expose my PAX and aircraft to the additional flight time on one engine in case something were to happen to the other one. That's where the probability and risk enter. I'd possibly be facing severe penalty if my judgement was wrong.
Certainly food for thought.
In my first post I mentioned the take-off alternate was required if the departure airport was closed to arrivals. Fair enough regarding Oz. I've not worked there for some time. It was the general principle of a take-off alternate, Australia excluded.
In the last post I apologise for my lack of clarity. I said "Of course with 2 engines operating, and engine failure probabilities being low, we would most probably keep going if time intervals were reasonably insignificant". I meant being already inside the ETOPS threshold for the airport that became unavailable.
With regard to your last point, you may well be correct. ETOPS defines the total area of operation. One may well be able to choose one's preferred airport. But I wouldn't wish to expose my PAX and aircraft to the additional flight time on one engine in case something were to happen to the other one. That's where the probability and risk enter. I'd possibly be facing severe penalty if my judgement was wrong.
Certainly food for thought.
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The surprise, discussed as part of the wash up afterwards, was the 3 tonne hole in the fuel plan options they thought they had with a useless engine plodding away alongside them as a very large, thirsty APU.
But I wouldn't wish to expose my PAX and aircraft to the additional flight time on one engine in case something were to happen to the other one. That's where the probability and risk enter. I'd possibly be facing severe penalty if my judgement was wrong.
What about if you had a 150kt crosswind all the way there or back?
Is there a difference, legally? Operationally?
a critical point or pnr (point of no return) is the last point you have fuel to divert or return to the airfield being considered
Critical Point or Equi-time point is where the TIME to two destinations is equal. It does not take into consideration fuel. It is all about TIME.
PNR is about how far one can fly, often from the departure airport but also can be an off track PNR, and still return to a nominated airport. PNR is all about FUEL which obviously translates to time in the air.
Because in aviation we are not happy unless we keep changing the name of things to suit the latest whim (AFIZ, MBZ, MTAF, non towered...) the acronym LPSD latest point of safe diversion is also used. I stuck with CP/ETP and PNR to KISS.
Am I missing something, happy to be wrong.
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I agree Icarus, CP and ETP are synonymous as far as ETOPS/EDTO is concerned. PNR is something entirely different.
In reference to the original post. After the engine rolled back surely thrust was restored?
In reference to the original post. After the engine rolled back surely thrust was restored?
a pnr/cp is by definition always "critical"
the acronym LPSD latest point of safe diversion is also used.
I am returning to ETOPS flying shortly and have started studying (sort of) before line training kicks in but I find myself a little confused. Either some rules have changed or my memory is getting as bad as my eyesight……
If an en route airport becomes unavailable after the EEP, re route or turn back is NOT required?
“Weather minima at diversion airport(s) going below the company/crew en-route minima, before reaching the ETOPS Entry Point, or diversion airport(s) becoming unsuitable for any reason.”
I read the above from FCOM as though we can continue if wx goes below landing mins after we pass the EEP? Does the same apply to the remaining comment in the passage – “…or diversion airport(s) becoming unsuitable for any reason.”
Thanks for any input.
If an en route airport becomes unavailable after the EEP, re route or turn back is NOT required?
“Weather minima at diversion airport(s) going below the company/crew en-route minima, before reaching the ETOPS Entry Point, or diversion airport(s) becoming unsuitable for any reason.”
I read the above from FCOM as though we can continue if wx goes below landing mins after we pass the EEP? Does the same apply to the remaining comment in the passage – “…or diversion airport(s) becoming unsuitable for any reason.”
Thanks for any input.
Once you dispatch you make the best decision you can with the available information and time available.
The end
When you pass your EEP (EDTO Entry Point) it is as you say. Up until that point, however, if the weather deteriorated at your island divert - or you had a mechanical issue rendering you no longer EDTO compliant - you'd have to turn back.
It just so happens that many Australian airlines have chosen to pervert this regulation and declare their EEP as dispatch, not at 90 minutes out from the last suitable aerodrome which by strict definition is the beginning of the EDTO /ETOPS area.
The obvious commercial advantage is that if the weather is good when you takeoff at all your bolt holes across the Pacific then you can sail on your merry way to HNL, even if every one fogged in 2 mins later. Other airlines would reassess the bolt holes just prior to their EEP which might be halfway into the flight and if they have deteriorated below EDTO Alternate minima, then the flight can't continue on that basis.
Last edited by compressor stall; 13th Nov 2013 at 08:17. Reason: Clarity
Iccy, I have always considered that PNR and LPSD are different. LPSD is an offtrack PNR ie to a place off track. PNR, by definition, is the point of no return to the place of departure.
A rose by any other name...
Etops is basically a planning exercise.
Once you dispatch you make the best decision you can with the available information and time available.
Once you dispatch you make the best decision you can with the available information and time available.
The important point in this incident is that it appears they had an engine operating at idle, thereby supplying services, versus an IFSD. Two different beasts. I look forward to reading more.
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When you say they turned back before the "CP", was this the CPE ("Critical Point ETOPs"), or was it the ETP (equi-time point)?
They are not the same thing.
An A330 CP (ETOPs) is calculated on simultaneous engine failure and depressurisation, which is the most fuel critical scenario. If you don't have both, the CP (ETOPs) becomes rather meaningless, not to mention that its calculation is a preflight requirement but not an inflight requirement. A cruise depressurised at 10,000ft with an engine out is not equal to a cruise at engine out cruise ceiling.
Now, they did not divert to the Marshall Islands (Majuro) but proceeded to to HNL:
For an A330 (at least in QF), Majuro is classed as a "Category C Airport". That is, it is only to be used as an "adequate" airport for the purposes of ETOPs planning. It is not an approved "Main" and it is not an approved "Alternate". In QF rules and regulations at least, it is stated crystal clearly that there is no requirement to land at the nearest adequate (i.e., a cat C) airport in the event of a critical systems failure.
The crew (at least if they were QF) were completely and totally within their rights to continue to Honolulu - and probably quite sensibly too. I've flown a lot into the remote Pacific airports and to force me to do it in an A330 the situation would want to be pretty grim.
**yes I'm qualified on the A330 in QF.
They are not the same thing.
An A330 CP (ETOPs) is calculated on simultaneous engine failure and depressurisation, which is the most fuel critical scenario. If you don't have both, the CP (ETOPs) becomes rather meaningless, not to mention that its calculation is a preflight requirement but not an inflight requirement. A cruise depressurised at 10,000ft with an engine out is not equal to a cruise at engine out cruise ceiling.
Now, they did not divert to the Marshall Islands (Majuro) but proceeded to to HNL:
For an A330 (at least in QF), Majuro is classed as a "Category C Airport". That is, it is only to be used as an "adequate" airport for the purposes of ETOPs planning. It is not an approved "Main" and it is not an approved "Alternate". In QF rules and regulations at least, it is stated crystal clearly that there is no requirement to land at the nearest adequate (i.e., a cat C) airport in the event of a critical systems failure.
The crew (at least if they were QF) were completely and totally within their rights to continue to Honolulu - and probably quite sensibly too. I've flown a lot into the remote Pacific airports and to force me to do it in an A330 the situation would want to be pretty grim.
**yes I'm qualified on the A330 in QF.