PDA

View Full Version : Dispatch point


linedriva
7th Aug 2011, 10:13
I'm trying to find a definition for 'dispatch' as far as MEL goes. I have a company definition, but I can't find a reference for Boeing.
I'm basically trying to work out if I can legally continue on an ETOPS plan if I get a pack failure after dispatch (according to the company), but before takeoff if the MEL says no to ETOPS.

sleeve of wizard
7th Aug 2011, 14:35
Considerations for Dispatch with Displayed EICAS and
CMCS Messages
Any monitored faults that affect airplane dispatchability will be displayed on EICAS as a Status or Alert level (Warning, Caution, Advisory) message, with a corresponding correlated maintenance message. System faults displayed at Status level or Alert level should be resolved by MEL compliance or maintenance action prior to engine start. After engine start, EICAS Alert messages are the primary means of alerting the crew to non-normal conditions or improper configuration. Display of any Alert message requires accomplishment of the appropriate non-normal procedure by the crew. Upon completion of the procedure and prior to takeoff, the operatorís MEL should be consulted to determine if relief is available for continued operation with system faults displayed at the Alert level (Warning, Caution, Advisory).

4dogs
7th Aug 2011, 19:36
First things first:

I'm basically trying to work out if I can legally continue on an ETOPS plan if I get a pack failure after dispatch (according to the company), but before takeoff if the MEL says no to ETOPS.

Technically, you could continue as the MEL is no longer applicable post-despatch until such time as you complete the flight. Legally, I believe the question of reasonable behaviour would subsume the technicality. I know that my first thought would be to question whether I want to take that problem airborne in all of the relevant circumstances, regardless of what the MEL says. Only if I decide that threshold question in the affirmative would I bother to see if I am permitted by the MEL to do so.

In Oz, "despatch" occurs when the aircraft first moves under its own power for the purpose of taking off, which is the legal definition of the start of "flight time". In effect, it attempts to practically recognise the point at which Ground Handling operations by the operator have, for all intents and purposes, ceased and the aircraft is solely in the hands of the Captain. There is an underlying presumption that return to the gate may not be practical and, from a risk management perspective, any post-despatch failures can, for the most part, be treated as airborne failures that generally will not reduce permissible certification system redundancies below an acceptable level.

Technically, the QRH becomes the primary airworthiness control document post-despatch. Thus arises our "Practical Gap" because the QRH rarely distinguishes between ground failures and airborne failures - it is, for all intents and purposes, the airworthiness control document that applies from the commencement of "time in service", that is, the commencement of the take-off roll.

So our "Practical Gap" is from disconnecting the tow bar until cleared for take-off where neither the MEL or the QRH practically apply to problems that may arise. The decision about how to resolve the issue is an element of command. Your command judgement is not controlled by the MEL or the QRH: they are considerations that must be weighed up amongst others in terms of the potential consequences of your actions, even if nothing else goes wrong.

And each situation will be different: I may well take a taxiway generator failure airborne on a clear moonlight night, but return to the bridge if it is dark and stormy, the destination involves a serious likelihood of diversion and there is a chance that water ingestion may be the cause.

And when it comes to taking risks, I haven't come across an operator yet that is worth placing myself at unreasonable risk to further their commercial needs! :=

Stay alive,

linedriva
8th Aug 2011, 19:52
Thanks for your responses 4dogs and sleeve. I know what I'd do practically, but looking for the legal answer. Sleeve, is your reference from the MMEL?

A wise Captain once told me everything is ACE!!! An ass covering exercise!

sleeve of wizard
9th Aug 2011, 01:39
Linedriva, straight from the B777 MEL

stormyweathers
11th Aug 2011, 17:38
Presumably, your company says that you cannot "GO" prior to "dispatch" for an ETOPS flight. The MEL does not differientiate whether it is ETOPS or not ETOPS...so (as per sleeve's post) I say you can LEGALLY go.