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MEL definition

Old 27th Nov 2014, 20:23
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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 !
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Old 27th Nov 2014, 20:52
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‘Commencement of flight’ is the point when an aircraft begins to move under its own power for the purpose of preparing for take-off.
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.
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Old 28th Nov 2014, 08:43
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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.
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Old 28th Nov 2014, 09:10
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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.
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Old 28th Nov 2014, 09:35
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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.
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Old 28th Nov 2014, 10:33
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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 ..
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Old 28th Nov 2014, 12:43
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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.
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Old 1st Dec 2014, 07:39
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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.
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Old 1st Dec 2014, 07:49
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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.
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Old 1st Dec 2014, 09:15
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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 ?
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Old 1st Dec 2014, 12:48
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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.
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Old 2nd Dec 2014, 01:33
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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.
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Old 2nd Dec 2014, 11:58
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For example our aircraft aren't defined as dispatched until take off power is set
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.
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Old 5th Dec 2014, 00:50
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Our airbus MEL says this...
The provisions of the MEL are applicable until the start of the takeoff roll.
If a failure occurs between Pushback (OFF BLOCKS) and the takeoff roll, flight crew must complete all actions as required by the failure, including ECAM Actions and then refer to the MEL .
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Old 28th Dec 2014, 11:29
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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
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Old 28th Dec 2014, 11:49
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After engine start, MEL and/or QRH apply in our joint. Plus common sense and captain discretion. All well written and explained.
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Old 28th Dec 2014, 12:15
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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.
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Old 28th Dec 2014, 16:14
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Prudent option is to return to dispersal
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.
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Old 23rd Jun 2018, 06:53
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So please give examples of which major airlines in Europe, apply the MEL up until takeoff power is set, and not just until start of taxi.
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Old 23rd Jun 2018, 07:21
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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.
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