ETOPS qns

[Glidermike]

A few ops qns:
I presume final fuel reserve must still be honoured under an ETOPS diversion (e.g. in case of fuel jettisoning to reduce weight)?

And thus the requirement for a 3-4 engine jet to fly level for 15 mins above aerodrome is not part of the final reserve?
Ditching certification is mentioned but not really described. Could you elaborate (out of interest)

Thanks - Mike

[Tom]

In EU OPS, the requirement for 'additional fuel' in the event of loss of pressurisation or an engine failure, and diversion to an adequate aerodrome is defined ...

... to allow the aeroplane to descend as necessary and proceed to an adequate alternate aerodrome in the event of engine failure or loss of pressurisation, (assuming the failure occurs at the most critical point), and .... hold there for 15 minutes at 1 500 ft (450 m) above aerodrome elevation in standard conditions ... and make an approach and landing ....

... in deciding if you need this additional fuel, you can take into account the remaining trip fuel and final reserve ... but as ever, you are going to put the aeroplane on the ground with final reserve in the tanks.

Ditching - EU OPS says that above 30 seats, and more than 400nm/120mins from land - the operator must ensure the aeroplane complies with the ditching requirements prescribed in the applicable airworthiness code ... now, for large aeroplanes, I think the detail is in CS25 ... and I need to have a look at that before I start talking rubbish - I am at BGS on Monday - so I will have a look then!!

Hope that is OK for now

Tom

[Jamie Fox]

This is purely out of interest because I've done my exams now. In any case, I don't think there were any known questions on this.

My reading of the additional fuel requirement is that, if in the event of depressurization/engine failure there is sufficient fuel on board to divert to the nearest adequate aerodrome and have 15 minutes holding at 1500ft, then there's no requirement to carry any additional fuel. Therefore, having diverted at the most critical point, you would expect to land with 15 minutes fuel remaining rather than the usual final reserve of 30 minutes. Is this correct?

And on a related point: if the requirement is to consider the additional fuel required in the event of engine failure OR depressurization, why do the two graphs at the back of the flight planning manual consider depressurization for both all engines operating and one engine inoperative?

[Tom]

Yes, you are correct ... in this EMERGENCY situation, you will put the aeroplane on the ground with at least 15 mins of holding (but remember , you have declared a mayday!)

So far as one engine or two engines go - the fuel critical scenario will be depressurization - .... you must consider both the engine failure case and the all engine case - you might just have a 'window blow out' ... you have lost pressurization, but you still have both engines - how much fuel required for this??

If you look in the CAP 697 - FIG 4.7.1a and b - the notes at the bottom tell you that to find the CRITICAL FUEL RESERVE, you must look at both charts, and take the higher of the two. (This will probably be from the ALL ENGINE chart - FIG 4.3.1b)

Tom