Return versus Diversion

[Lairyliam 17]

 

if you read the report ...

 

https://assets.publishing.service.gov.uk/media/542302bfe5274a1317000bd7/Boeing_747-436__G-BNLG_06-06.pdf

 

 

I am aware of this happening, but never read the report, what an indepth factual read that was. ( I didnt read the whole thing) But thanks for sharing.

 

Liam

[BlueStar 323]

Where are you getting your numbers from?

 

A former B744 FO that I fly with from time to time.  She just came off the B744 and has about 5,000 hours on it.

 

How many hours do you have on the B744, Simon?

 

blaustern

[skelsey 765]

Sigh.

 

OK, you do the sums. I actually got mine wrong - as you will see, I'd actually assumed the numbers were without reverse. In fact they assume all four reversers in use, so the number is even more than I calculated.

 

Perhaps your friend flies a different variant (I still can't find a picture of a -400B) but I can't see how you could get the landing distance below 7000ft at MTOW. If I am doing the sums wrong then please educate me.

 

 

As I say, whether you can get it stopped is irrelevant really because of the brake energy issues, which you have not addressed.

[phil747fan 14]

Hi Wilhelm,

 

 

 

 

What is a 747-400B? Where are you getting your numbers from? At 395 tonnes (i.e. slightly under but near as dammit MTOW) the best I can get from the QRH with F25 is 2660m with max manual braking, which is just over 8,000ft.

 

Regardless, as I said in my post you can do it, but as you will know with your experience that it is not just about landing distance alone. The big limiting factor is the brake energy and if you land a 747-400 on an 8,000ft runway at MTOW you will unquestionably melt the brakes and fuse plugs. If you are on fire then clearly this is a better outcome than burning in the air. However, ending up disabled on the runway with 16 flat tyres and burning brakes to me, again, would seem to be a rather extreme and disproportionate response to a compressor stall. Do you not agree?

 

 

 

 

That is not true. If you read the report, you will see that several other carriers had similar or identical flight continuation policies, and from a legal perspective Boeing, the CAA and the FAA (at the time) all agreed that a single engine failure on a four-engined aircraft with no other aggravating factors is not a case for immediate panic and diversion. The airframe manufacturer, the engine manufacturer, the regulators and the operator all agreed that the aircraft was in a perfectly airworthy condition to continue the flight, that there no risk of further damage to the engine or airframe as a result and that:

 

 

Again, I'll stress that the Commander didn't make an immediate decision to continue the flight to destination. The decision was to continue, assess the situation, route in such a way that ensured there were plenty of options available and divert if anything adverse appeared at any point during the flight. What is unreasonable about that, given that the decision was considered and made within the framework of the FCOM, QRH, well-established written and regulator-approved operator policy and the law?

we at the time operated tow different kinds of 747-400 and we in the ops had to divert even just for a surge (in the report one operator was doing it already maybe us ...). i read the report i even provided the link lol ... US operators after that were given by the FAA that the diversion was the only option no continuation of flight ... and if you look on the report :..''...

The aircraft manufacturer did not provide guidance as

to the acceptable period of continued flight following

an IFSD ...''... so BAW did it over 11 hours when even the builder had no clue how long it can be conducted ...

 

technically the plane can do it but in aviation there is always the if especially with PAX in .... just remember also that BAW promises they wont do it again ...

Simon i will check what i have for RR engines and landing with three reverses working at MTOW ... but there is certainly a lot of penalty. as it was not an emergency and at first they circled around LAX there is a chance that they considered landing back after a while and not being at MTOW but more MLDW which is a different story even with 3 reverses working ...

[skelsey 765]

 

 

US operators after that were given by the FAA that the diversion was the only option no continuation of flight ...

 

(my bold)

 

Again, whether the FAA decided to change the regulations after the fact is irrelevant. The crew made their decision based on the regulations and precedents in force then. How could they do otherwise? If the road outside my house has a 30mph limit, and one day it is decided that a 20mph limit should instead be enforced, would I then be wrong to have driven at 30mph prior to the new speed limit, or should I have driven at 20mph instead just in case one day someone decided to change it?

 

 

 

and if you look on the report :..''...
The aircraft manufacturer did not provide guidance as
to the acceptable period of continued flight following
an IFSD ...''... so BAW did it over 11 hours when even the builder had no clue how long it can be conducted ...

 

But they had also issued a notice to operators stating:

 

 

‘windmilling the engine for lengthy periods without engine oil does no harm to the bearings within that engine. In engine terms therefore, a flight may continue after in-flight shut down for oil loss. Should an Operator nevertheless wish a flight to return or divert in such circumstances, this remains an airline decision based upon commercial/operational considerations.’

 

While these observations relate to an undamaged engine, the manufacturer did not foresee further major damage resulting from windmilling an engine with damage similar to that sustained by G-BNLG’s No 2 engine for a period of 12 hours or more.

 

Essentially, RR had a documented history of no technical objection, and with the sort of telemetery installed in modern engines I would be very surprised if the airline had not consulted them during the event in any case.

 

If your operator had a policy to divert immediately to the nearest suitable airport in the event of any problem that is fine. However, BA did not then, and as far as I know still permits its commanders to exercise their judgement now.

 

 

just remember also that BAW promises they wont do it again

 

Just because the FAA threw their toys out of the pram does not make the decision unsafe. What would have been safer about flying in circles over LA for an hour or two dumping fuel, rather than flying in a straight line east with literally hundreds of B747-capable diversion airfields within easy reach for hours on end? I suspect that if the same thing had happened at 400ft ex-CPT, for instance, the crew may well have elected to return rather than head out for 11 hours over unforgiving terrain with limited diversion options.

 

That is precisely why BA provides its commanders with the flexibility to make a decision based on facts in this situation rather than simply applying a blanket policy. Engine surges and is shut down over the middle of Africa in the middle of the night. What is safer: immediate mandatory diversion to somewhere completely unfamiliar to the crew in the middle of nowhere with perhaps poor ATC, limited facilities for the passengers and limited repair facilities, unreliable approach aids, poor lighting etc or a gentle driftdown and continuation towards destination, monitoring the situation and keeping options open for diversion in the event of any further issues?

[BlueStar 323]

 

 

you do the sums

 

Simon,

 

I don't have to do the sums, it is in the test flight data when the aircraft was certified. 

 

As for my friend, she just made Captain on the B777. 

 

blaustern

[skelsey 765]

Wilhelm,

 

I don't have to do the sums, it is in the test flight data when the aircraft was certified.

 

Well it's not in the current QRH, or any other documentation, so I'm not sure how anyone is supposed to make use of this data then.

 

Congratulations to your friend!

[BlueStar 323]

Wilhelm,

 

 

Well it's not in the current QRH, or any other documentation, so I'm not sure how anyone is supposed to make use of this data then.

 

Congratulations to your friend!

 

I know you will find this hard to believe, but you do not have access to all the pertinent data. 

 

blaustern

[skelsey 765]

 

 

I know you will find this hard to believe, but you do not have access to all the pertinent data. 

 

Could you please explain to me where, if not in the QRH, a pilot would find the pertinent data to do the calculation you are referring to?

 

I'm very happy to have a discussion about the merits of an immediate return over a diversion but so far all you have done is insisted I am wrong about something which is an absolutely straightforward black and white calculation, despite refusing to provide any actual hard data or calculations whatsoever to the contrary or explain where I am going wrong, so it's a bit difficult to get anywhere if I'm honest.

 

Again, if you can show me a way of calculating an LDR at MTOW of 7,000ft/2130m from the data I have provided above, or point me to the name of the document that I should be looking at instead, I'd be very grateful as this would expand my understanding.

 

Do you have any comment on the brake energy issues I highlighted previously?

 

Best,

 

Simon

[G-CIVA 62]

'Do you have any comment on the brake energy issues I highlighted previously?'

 

No but apparently he does have a special friend though on the 'inside' so that must cancel out your reasoned logic.

[phil747fan 14]

not sure Simon but if you used Freighter data i think it is even less strenght on the fuses for the Pax version. 

[BlueStar 323]

 

 

Could you please explain to me where, if not in the QRH, a pilot would find the pertinent data to do the calculation you are referring to?

 

Look in the "Landing" chapter in the FCTM. 

 

blaustern

[phil747fan 14]

Look in the "Landing" chapter in the FCTM. 

 

blaustern

Simon tried to explain to you  ...

you may exceed the brake energy limits ...

 

i ve been on a jumpseat for a test on overweight autoland ... briefing was interesting ....

[G-CIVA 62]

Look in the "Landing" chapter in the FCTM. 

 

blaustern

 

You see, the thing IS ......

 

Simon actually gave you a reference from a table that real world pilots reference in the the real world i.e from the QRH.

 

During an actual flight they would be referring to numbers & tables contained with in the QRH, its called the QRH because it is a Quick Reference Handbook.  Within the Performance Inflight Chapter is all the Information the Flight Crew requires to operate the aircraft under Normal & Abnormal conditions once airborne.

 

It saves a busy flight crew the task of sifting through the many many pages contained within the FCTM which is best read over a nice cuppa whilst tucked up in bed or in the classroom.  An FCTM is a Flight Crew Training Manual, not a Quick Reference  Handbook.

[BlueStar 323]

 

 

You see, the thing IS ......

 

Mr. Bell,

 

No Mr. Bell the thing is I was a commercial and military pilot before you were born.  You and Simon have slander and belittled me while I have tried to add some real world insight into commercial flying.  That is a mistake I will not make again.

 

Grace and Peace,

 

blaustern