When do you "dispatch"?

[James Brake]

You are governed by the requirements of the aircraft MEL (with regard to aircraft deficiencies) up until the point at which you dispatch.

When does this happen?

My feeling is that is at the start of pushback, but have also been told that it is when the aircraft first moves under it's own power, or alternatively, at the start of the take-off roll.

Does anyone have a reference for this?

thanks

Jim

[bafanguy]

JB,

I'd imagine this would vary from one country/airline to another. I can quote from my former US employer's MEL:

"For the...MEL purposes, "Dispatch" is defined as the advancement of the throttles for the purpose of taking off (takeoff event). If the takeoff is aborted for any reason, the MEL provisions and limitations become applicable once again."

Just one definition, I guess.

[Hand Solo]

In BA we use when the aircraft first moves under its own power.

[JackOffallTrades]

As I understand it, prior to the point of dispatch the crew should refer to the MEL for guidance with regard to their fault. After that the QRH or any other inflight procedures should be applied (such as ECAM drills on an Airbus).

However, after the point of dispatch consideration should be given to the MEL and its implications as they could prevent further dispatch (e.g. if the flight is outbound from an engineering base to an out-station with no cover).

A report I read where a BA 744 departed, and during the taxi had an EPR guage fault and reverted, quite correctly to an N1 mode. Fine, the a/c had taxied away under its own power so the crew simply refered to the QRH for the procedure.

Had the crew also refered to the MEL they might have spotted that this fault would inflict a performance penalty. Given the weight of the Jumbo at the time, they would not have been able to take-off.

Fortunately the B747 departed without incident.

Jackoff.

[Scallywag]

James - Our reference, or definition, is in the "preamble" of the MEL.

We use.......when the aircraft first moves under own power.

[FlightDetent]

My outfit has the paperwork set to the first mov ement under own power as well. However, the company still us asks to review the MEL and contact the OPS and maintenance squads before departure (single hub operations here) to decide, return capability being a factor.

Further more, all of us know that 737 NNC says that EQPT Cooling OFF thou shall select the alternate fan, and if that fails as well, well ... no crew action required. Ha, ha. On the other hand, the MEL admis that single fan dispatch is still possible but on the very contrary to the QRH, should the single working fan fail, in 90 minutes one may face "loss of essential flight instruments".

Our flights to DUB are 2:00 on averge, CAI standing at 3:15, still not speaking of the extremes that reach 4:20 on the return leg, 737 classic speakng.

Airmanship should be revealing here I guess, and luckily being just another CM2, it is not me who gets to decide...

Cheers,
FD.

[TopBunk]

Hand Solo is not quite correct.....

In BA dispatch when first moving under own power is correct for Airbus (and shorthaul?), but on the 747-400 (and 777?) you have dispatched after commencement of first engine start.

[Disclaimer: that's what it was on the 747 back in 2001].

[bafanguy]

Top Bunk,

Now I have a question. If I understood James Brake's original question, he wanted to know at what point the MEL ceases to be a legally-binding document for the operation/crew, saw this point as the moment at which you are "dispatched", and wanted a definition of "dispatched".

From your comments, did you mean you are no longer legally bound by MEL restrictions at first engine start/moving under own power ? So, you could ignore the mechanical discrepancy if it occurred during taxiout, for example, and takeoff with no further legal encumbrance because the problem appeared AFTER you had moved under your own power ?

I suspect we're comparing apples to apples more than it would appear. For us, the MEL is legally binding any time the acft is on the ground until "..the throttles are advanced...", as I quoted before. It isn't tied to a particular point of progress durng ground ops prior to that point.

Our particular MEL procedures are further complicated by "pilot placarding procedures" where the crew can legally inop some items without the services of a mechanic. The implementation of this twist is, in fact, tied to various points of progress while on the ground ( I won't bore you with those).

[Smoozesailing]

Remaining on the MEL issue, I'd like to digress a bit.

Certain MELs have conditions that have to be complied with in order to defer the defect, such as having the ECAM switch working in case of an ADIRU failure (on the A330).

Now according to one maintanence engineer in my outfit, the requirements for defering the defect have to only be met at the time of the deferment. Once the defect has been defered, the requirements do not need to be met. In this case, if the faulty ADIRU has been defered, and the ECAM switching becomes faulty later on with the deferment still active, the deferment is still valid and the aircraft is considered airworthy

Sounds fishy if you ask me.:confused:

Can anyone confirm this?

[john_tullamarine]

I think one needs to consider some of the philosophy ...
the aircraft is designed to meet a specific set of airworthiness and operational specifications and the TC attests to the design's compliance with such specifications

the individual CofA carries the general TC approval forward to the individual aircraft

the MR, likewise, carries the CofA approval to the day to day level of things
The basic presumption is that if a TC-related item is broken, the bird stays on the ground until the thing is fixed - otherwise the operation would involve a non-compliance with the Design Standards.

That's fine .. but totally unworkable and unreasonable in the real world.

Thus we have the idea of MMELs and resulting MELs.

The MMEL is the result of the stakeholders' looking at the effect of a problem on the aircraft's operation, specifically in respect of the problem's relationship with the Design Standards. If the think tank can come up with a set of restrictions which mitigate the risk associated with aircraft operation carrying the defective item (from a TC viewpoint), then operation with the defect, in accordance with the requirements of the MMEL, results in a situation similar to the fully serviceable aircraft from the point of view of redundancy, and so forth. These requirements ultimately find their way to the operator level via the MEL derived from the MMEL.

Hence
INTENTIONAL operation with a defect involves a detailed consideration of the effect of that defect on the TC basis for the aircraft design. Necessary maintenance and operational restrictions to account for the defect while maintaining equivalent compliance with the Design Standard are built into the MMEL and, in turn, the MEL.

CONTINUED operation with a defect occurring during the sector is concerned with recovering the aircraft to a safe landing and may involve a level of risk higher than that implicit in the Design Standard.
The despatch thing tries to put a line in the sand to define where intentional operation with a defect becomes continued operation and, naturally, there will be various approaches to this definition in the same way that there are variations in most things from one jurisdiction to another.

Consider though that, prior to takeoff, the pilot still has an option to get the bent bit fixed, even if the definition permits him/her to continue.

From a practical airmanship point of view, the pilot who mindlessly accepts a newly developed defect on the basis of QRH/AFM words alone, and without considering the MEL requirements, is acting a tad capriciously, I suggest.

[Carnage Matey!]

TopBunks a little out of date with his 747 info. That fleet has fallen into line with the rest of BA and 'dispatches' when it first moves under its own power.

[Cough]

BA point of dispatch is as above. However, through my training I was always told to refer to the MEL 'just in case there is a little gem of info in there'. The MEL is not binding after brakes release, but at least you know what you are getting into.