MEL definition
 

A quick question for the knowledgeable :

I am looking for the definition of "commencement of flight" with regard to MEL.

I want to find the present valid EASA documents on this.

Thank you !

CS-MMEL (Certification Specifications and Guidance Material for Master Minimum Equipment List), Book 2 – Guidance Material, Subpart B, Master Minimum Equipment List, GM5 MMEL.120 Format and content of MMEL, Definitions And Explanatory Notes

For an older reference to JAR:
Commencement of flight is defined in JAR-MMEL/MEL.001(d) and .005(d) as “the point when an aircraft begins to move under its own power for the purpose of preparing for take-off.” In the case of a helicopter, it refers to the moment the helicopter commences air or ground taxi.

So, MEL working on the ground until "the point when an aircraft begins to move under its own power for the purpose of preparing for take-off", after that point- QRH only.

Not QRH only ! Life's not that simple. You would be foolish not to consult the MEL after taxi particularly for take off where the failure affects performance (or indeed something that will stop you returning from destination). That's Captaincy



For example Antiskid fail. The QRH says nothing but the MEL details the various takeoff performance penalties which you must still apply whether you have dispatched or not.

And just be careful because it CAN be airline specific. For example our aircraft aren't defined as dispatched until take off power is set. So any fault prior to takeoff is subject to MEL.

And just be careful because it CAN be airline specific

Generally, such will be the case.

The MMEL must be tailored to suit the operator and then processed through whatever regulatory approval process applies in the particular jurisdiction.

Sometimes the regulator will help out - developing an MEL is a painful exercise - as, for instance, in Australia where, for a period, CASA developed a generalised MEL (GMEL) for given Types which the operator could purchase for a fee much more attractive than the cost of a do-it-yourself animal. The GMEL system fell into disuse for reasons I have never discovered ..

Having had some involvement in MEL (and GMEL) development and defect investigation, I can only shake my head at the philosophy that holds a flight starts prior to takeoff ..

EASA Air Operations Requirements ORO.MLR.105 MEL


"The Operator should include guidance in the MEL on how to deal with any failures that occur between the commencement of the flight and the start of the take off run".


As I understand it this guidance should include how to comply with the O&M procedures in that period between taxy and take off.

8che, you"re on! ..."the point when an aircraft begins to move under its own power for the purpose of preparing for take-off, after that point- QRH only." It means- if you are on the RW and start moving for T/O. Sure, if you taxi to the RW and EICAS messages appears, NNCL first, MEL second, decision third. But if you start moving on the RW for T/O purpose, QRH- first and later you CAN use MEL, but for reference only.

If you fly for an outfit that doesn't clarify exactly what is expected between pushback and comencement of the takeoff roll then you probably fly for a crap outfit.....if that is the case, the safety of the paying public relies on the Captains sound judgement and knowledge only. No systemic back up. It'll work well most of the time, it won't work well when the Captain is a fruit-loop.

Thank you Skyjob for the EASA reference.

When you read the definition on commencement of flight, it says
"the point when an aircraft begins to move under its own power for the purpose of preparing for take-off".
You could read this in two ways, either as beginning of the taxi phase, or the Take Off roll. But in the "old" JAR documents it says further :

"The operator's MEL should include procedures to deal with any failures which
occur between the start of taxi or push back and take-off brake release (see
ACJ to JAR-MMEL/MEL.001(d)). Any failure which occurs after take-off
commences should be dealt with as an in-flight failure, by reference to the
appropriate section of the Aircraft Flight Manual, if necessary."

(do you have the above as an EASA document ?)

As I understand it, "the point when an aircraft begins to move under its own power for the purpose of preparing for take-off" means the taxi phase, agree ?


If that is correct, then according the above, we should have tailored "on-ground Abnormal Procedures" (we fly Airbus`s) to cover the part of the flight from were it commences (beginning of taxi) until T/O ?

The EASA reference given is and can be explained either way. So it is up to an individual operator to establish the policy for its fleet and remove ambiguity.

As 8che mentioned, some operators rely on Captaincy to return to stand should a failure occur prior to departing during taxi, some require a return to stand no matter what.

Some failures (eg turnoff light failing) are benign but others (eg an antiskid failure) not so. Captaincy requires the Captain of the vessel to make an informed judgement call (decision) whether to continue the flight, having established the failure prior to departure, or to return to stand and have it looked at by Engineers, or speak to Engineers before continuing the flight without a return to stand, or to refer to MEL/CDL and assess if possible to apply restrictions for the flight to be undertaken instead delaying the aircraft further even though the restriction is not (yet) raised as a defect in the technical log of the aircraft.

There is no EASA defence to Captaincy and the area between the lines is in the hands of the Operator to define.

The definitions will not save your a$$ , but your decisions. Your company will ask you at the end. It is always good to check MEL for futher actions and it gives you vaulable information.

Folks,
That is close enough to the FAR definition for government work, the MEL applies up to the point of commencement of takeoff. It definitely does not mean commencement of taxiing.
Sorry I can't give a reference, too late at night.

PS: Have a look through a B744 or B767 etc. MEL, at the king of things that can happen between commencement of taxi, and ask yourself if you would want to get airborne.

Our airbus MEL says this...

MEL are NOT legally binding ONLY after the takeoff roll has begun.
From the moment the plane moves under its own power to takeoff roll, MEL are still legally binding.

The spirit of the sentence is that if you have an APU fire after pushback, first you deal with the fire drills as per QRH, then eventually consider a dispatch with an inop APU, though I guess first you want to investigate the fire damages :E

After engine start, MEL and/or QRH apply in our joint. Plus common sense and captain discretion. All well written and explained.

Start of flight is although company specific there are far too many issues to consider before you take off and it is not possible or practical to apply MEL during taxi and if you ignore it because by definition the flight has begun it could have serious implications and land you in trouble. The least of which is getting grounded at destination where maintenance is not available. Prudent option is to return to dispersal switch off and do the needful.

And herein lies the discretion of application.
If a failure would occur at home base with engineering support it may be more prudent to return to stand, whereas if the same failure had occurred down-route at an outstation it would probably more prudent to "return to dispersal".
Same failure, different choice made by, but both governed by the same definition in MEL, both correct.

Just to be clear, it's misleading in this discussion to say 'the MEL applies'.
The MEL does not 'apply' anything. What applies is that you go back to the gate, open the doors, enter the defect in the tech log, call an engineer, wait an hour for the engineer to arrive, and THEN, if the fault cannot be cleared in a reasonable time frame, possibly apply the MEL in order to dispatch.

This is what EASA states in its document 'Certification Specificationsand Guidance Material for Master Minimum Equipment List CS-MMEL':So it is very, very, very clear till what stage a defect needs to be entered in the Tech Log, rectified by an engineer or possibly deferred under the MEL: the release of the parking brake for taxi.

You'd be surprised how many pilots don't grasp this simple fact

100% agree, my previous operator had exactly the same wording in our OM(A) and that cleared any possibile doubts amongst the pilot population. My current one uses the wording "commencement of the flight" which should still be pretty clear but does indeed create confusion sometimes over a widespread fleet. As we all know most of the times wording is kept in such a way that it can be twisted and interpreted as needed depending on whom is supposed to be right or wrong :E

Same as PENKO.

From our FOM:

''The crew must refer to the MEL if a failure occurs or a component is degraded or a function is inoperative before taxi-out. If a failure occurs between the start of taxi ( when the aircraft begins to move under his own power) until the start of the takeoff roll it is subject to good pilot judgement and airmanship. The PIC may refer to the MEL to make an assessment before any decision to continue the flight is taken. This is particularly true for those failures that might affect the takeoff performance (i.e loss of spoilers, brake failure, etc.).''

Maybe where you are, WE are on the headset for departure at our airline! :p

Many MEL '' No dispatch'' are conservative and therefore not busine$$ friendly so it would not necessary make sense to return to the gate especially if you are in a remote area where they would not be able to fix the aircraft. Most of the time, it will have zero effect on the flight as there is redundancy. As long as you are aware of the potential consequences and comfortable with it. Then why not continue. I personally like the way it is. :)

Maybe since we are still att the gate, probably with no pax on board with engines shut down, and maintenance available it's worth it to try and fix it? During taxi we are left alone. xD
Just speculating. I'm not sure why. xD

The MEL provisions also consider the worst case scenario of a subsequent inflight failure of another critical system and therefore protects You accordingly. Once the applicability of the MEL ceases it is up to You to cater for all the different scenarios that could happen and decide. Regardless of what the MEL says the final word is anyway always with the flight crew (ie the Captain) if a more restrictive interpretation of the MEL is required given the conditions of the day.

If you ask me what is whise, then yes, of course, the MEL is one of the things you consider in your scenario of ECAM during taxi. The MEL is also a wonderful companion with ECAM in flight if time permits, or reading FCOM in bed at home.

If you ask what are the rules, then the rules are very clear, see my quote in an earlier post.
If you disagree with this, then please explain why. I pointed out that EASA also has the provision regarding failures during taxi. This should answer your initial question.

As for your point that we need tailored on ground procedures for dealing with failures, well, that's exactly what you have in your MEL: once dispatched but before TO, complete the QRH/ECAM and consider the implications of the MEL, maintenance facilities etc and then decide to go or not. But you are not bound by the MEL at that stage.

That's a different discussion jaja. An interesting discussion for those quiet cruise portions on a long flight indeed, but still a different discussion.
Now we can produce a long list of failures and ask 'would you take off'. Or we can ask one simple question: why have the regulators chosen the moment of taxi as the start of a flight with respect to defect handling? Apparently they trust our professionalism.

Fair enough, no?

Well You can't that's why You need to balance risks, assess the situation and come up with a decision using all the available tools. If possible a phone/satcom/HF call to your maintenance team while at the holding point could give you valuable inputs to come up with your decision and if you're still stuck a call to your duty pilot (if there is one where your work) can help you out as he is going to speak on behalf of the company even though he's not going to decide for you but most likely give you "food for thoughts". Main thing when in a grey area is to get as many inputs as possible before jumping to a decision and being told "oh yeah but you could have talked to etc..". In the end no one decides for You but if the feeling You get from all around is that it smells "dodgy" then the parking bay is where you are heading to.

https://cimg3.ibsrv.net/gimg/www.gmf...3f83d4121d.jpg

Clear I would hope...

This is not EASA-based.
So to be clear, you would go back to the gate for say..a burnt turn off light?

Why so paranoid? It's perfectly legal, no tech log entry necessary after you've dispatched. Any professional engineer will have no hesitation to advise you to go or not go, in writing, or on a recorded phone conversation.

I'm glad I work with sensible professionals who are not afraid to offer sensible advise or take sensible decisions. Also in writing when requested.

Boeing 767 DDG quotation "Upon completion of any applicable procedures and prior to takeoff, the operator’s MEL should be consulted to determine if relief is available for continued operation with system faults displayed at the alert level (Warning, Caution, Advisory).", so Boeing's policy is: if after or during engine start and before TO there is an alert message: 1) do the respective non-normal checklist (NNC), 2) check the DDG or MEL to make decision. For me, it is still unclear what to do if on this stage and before ETOPS entry point there some issues related to ETOPS MEL ITEMS and which usually not considered for NON-ETOPS flights.