Overweight landings and aircraft checks

[QuEsT147]

Hi all

had a discussion with a coleague recently regarding overweight landings and following aircraft checks. AFAIK you dont need to send the aircraft for the inspection if vertical speed at touchdown is less than 360 ft/min at MTOW, no matter how many overweight landings you make.

But he said, that even if this is true, no limit values exceeded, you still have to send the aircraft for inspection after certain number of overweight landigs, regardless of how low the touchdown vertical speed was.

Who is right?

Thanks for your opinions, gentlemen

QuEsT147

[TURIN]

What does your AMM say on the subject?

[QuEsT147]

Hi Turin

unfortunately, I dont know, since I have no access to any AMM. I am just aviation enthusiast, using this perfect forum to gain more knowledge and hoping that you, professionals, will answer my questions :)

Anyway, thanks for your reply :)

QuEsT147

[extreme P]

AERO - Overweight Landing? Fuel Jettison? What To Consider (http://www.boeing.com/commercial/aeromagazine/articles/qtr_3_07/article_03_4.html)

"The Boeing airplane maintenance manual (AMM) provides a special inspection that is required any time an overweight landing occurs, regardless of how smooth the landing."

[Occy]

I would suggest at any weight, a touchdown with a vertical speed of 360 ft/min would probably warrant some kind of inspection.

[QuEsT147]

Hi all

Thanks for your answers, much appreciated:)

QuEsT147

[glhcarl]

It is called an "Overweight Landing Inspection". Note that "Landing" is singular, ie no "s" on the end.

[Intruder]

I would suggest at any weight, a touchdown with a vertical speed of 360 ft/min would probably warrant some kind of inspection.
How would one know the rate of descent at touchdown?

There is also such a thing as a "hard landing inspection" in addition to the overweight landing inspection...

[ei-flyer]

intruder,

you may happen to glance at the vsi, very easy to interpret in a millisecond when you have substantial time on type. in any case, following a hard landing, this can be obtained from the FDR.

[john_tullamarine]

Some thoughts -

(a) MLW is a TC/AFM limit so any overweight landing contravenes the aircraft limitations which has reporting and followup consequences. For those who think otherwise, do you, then, routinely, and intentionally, takeoff at weights in excess of the MTOW/RTOW ? .. same philosophy applies.

(b) the vsi, very easy to interpret in a millisecond

except for the PEC's doing strange things in ground effect. VSI reading is not much use.

(c) this can be obtained from the FDR.

generally not achieveable due to inadequate sample rates

[boredcounter]

In the case of a 'Hard Landing' would this be downloadable to assist?

Can a Boeing type engineer please confirm for me:

Hard landing (as I have called it) = excessive sink rate/g for want of a better definition.

Heavy / Overweight landing, the same thing, exceeding the MLW of the airframe.

In a previous (non-flying, non-engineering, hell yes, Ops ) life, "Heavy' was excessive sink/g and 'Overwieght' was just that and a hard landing was the F/o's as reported by the Captain.

Now I work with Boeings, thats why I ask for clarification.


Thanks in advance,

Bored

[Quality Time]

I don't think that disregarding MTOW/RTOW and landing over Max landing weight reflect the same mentality.A line pilot may occasionally expect to do the latter and be trained to do so under some circumstances.

One of them is clearly considered and accounted for because for most aircraft the MTOW is significantly higher than the MLW. The manufacturers consider this and account for it and it may well be discussed in Operations manuals. Of course it has some implications as you suggested.

Taking off over MTOW is not something normally considered.

[TURIN]

How would one know the rate of descent at touchdown?


The Airbus family and B777 have on board data systems that record various parameters during the 'touchdown'.
Some airlines will have the system programmed to automatically printout a copy in the flight deck and/or send an ACARS to base for evaluation.

The Boeing is pretty straight forward to interpret.
The Bus on the other hand requires a masters degree in quantum mechanics and relies heavily on the Heisenberg Uncertainty Principle. ;) (http://www.bbc.co.uk/dna/h2g2/A408638)

[BigJoeRice]

"Can a Boeing type engineer please confirm for me:

Hard landing (as I have called it) = excessive sink rate/g for want of a better definition.

Heavy / Overweight landing, the same thing, exceeding the MLW of the airframe."

See my response to this in the Engineers section.

[john_tullamarine]

I don't think that disregarding MTOW/RTOW and landing over Max landing weight reflect the same mentality.A line pilot may occasionally expect to do the latter and be trained to do so under some circumstances.

I am utterly astounded that we are having this discussion ... if the above be true, then which other limitations in the AFM limitations section are optional .. rather than required as part of the Type Certification ?

Caveat - we are talking non-emergency situations here.

[Quality Time]

JT

' Utterly astounded ' Maybe a little dramatic there John?

How do you define 'emergency' ? Does it have to be a 'Mayday' call or will a 'Pan' do? Is the passenger really having a heart attack or should you hold overweight until you find out for sure?

The point I was making is that I never expect to deliberately Take off over the limit but I have and may again land over MLW.

In fact I was in the company of a very senior technical pilot from a certain well known aircraft manunfacturer the other day and I put to him the scenario in the other thread on this forum about overweight landings. He didn't hesitate - he would land unless it was specifically prohibited by the applicable rules.

BTW IMO returning to land at the departure airport for a technical reason is not the same thing as 'in flight re-planning' as defined in operations manuals I have seen. The latter normally occurs on long flights with a change of destination and is effectively the same as planning the flight on the ground so it requires similar considerations. EG Landing factors.

In any event our Ops manual is quite clear that different factors apply once airborne to those at the planning stage on the ground.

[john_tullamarine]

Maybe a little dramatic there John?

I don't think so.

How do you define 'emergency'

One could be facile and cite the regulatory words for a given jurisdiction. However, a simpler view is anything which the commander considers warrants such a declaration.

In exceptional cases

.. which, to me, infers an emergency situation ...


Several points are pertinent -

(a) MLW is a limitation, no different to any other

(b) if you land in excess of MLW then you may be called upon to justify your actions either to the Regulator or the judiciary .. especially if a mishap ensues during the event

(c) to avoid the problems inherent in (b) I would only consider an overweight landing if I had a defensible risk based argument and could argue that the circumstances warranted declaring an emergency. An alternative acceptable circumstance might be one which involved the declaration of mercy flight provisions.

IF your ops manual has been Regulator approved and permits/directs an overweight landing in specified circumstances then that is a different situation.

If your views differ, that's fine .. but I know which option offers the best chance of a peaceful night's sleep .... perhaps you ought to seek local jurisdiction legal advice ?

Philosophically, I see no difference between busting the MLW limit for convenience and breaking any other limitation or regulatory requirement.

Perhaps I'm just an old dinosaur brought up in a different world ?

Hopefully some of our legally competent folk will offer an opinion or two ..

[Quality Time]

(a) MLW is a limitation, no different to any other


But it is different.
Why do Boeing and Airbus both give guidance on overweight landings?

If your views differ, that's fine ..

My views are far from isolated. They developed from listening to lots of other peoples opinion and experience and company guidance- including for example the gentleman I mentioned in my previous post. If I had discussed this scenario with my friends (Airline Captains)and they all said 'no way could you land' I would have to rethink my position. That has not been the case. Some would hold to MLW, some would land immediately and others would hold to an intermediate weight to increase margins if required.

From a technical point of view I don't think there is a major issue. There appears to be significany divergence on the requirement to do so and any consequences thereof.

Finally I am not suggesting for one minute that landing overweight is optional under normal circumstances but I don't think you have to be on fire with an engine out before you can do so.

BTW would a 'legally competent' person make the same decision as a competent aircraft Commander?

[Quality Time]

Sorry a little OT for this thread maybe we should combine the two threads?

[Tinwacker]

Just had an A330 landing OW after a divertion into BOM due 'All toilets inop'.
Not an emergency but then to the person busting a bladder it was.

OW weight inspection carried out.
The AMM for Hard and OW landing checks might at first hand seem a touch difficult but to follow the printable report 15 and the AMM graphs it's quite easy even for an old:mad:r

TW

[john_tullamarine]

But it is different. Why do Boeing and Airbus both give guidance on overweight landings?

I suggest that there is no fundamental difference at all.

Now, no-one is suggesting that overweight landings will not, and do not, occur. The only question of material interest is whether such a given landing might have been appropriate or inappropriate (and, I guess, if it were to get to Court .. legal or not so .. with the potential for legal censure in the latter event .. ie loss of certificate, fines, or time in the Big House according to jurisdiction and circumstances).

The situation is -

(a) the particular Type is designed to meet/exceed requirements specified in the relevant Design Standard (eg FAR 25).

(b) each individual aircraft, as part of the build and release process, is inspected and certified as being in compliance with the TC. At the end of the process a Certificate of Airworthiness is issued .. this document, in summary, attests to that compliance status.

(c) operational, maintenance, and general continuing airworthiness requirements have, as an implicit basis, continuing compliance with the Standards.

(d) part of the body of compliance involves a bunch of declared limitations which the pilot finds in the AFM Limitations Section (or, more commonly, in the company operations manual .. which should incorporate all pertinent AFM data)

(e) the MLW is a Certification limitation and, as such, is NO DIFFERENT to any other ... MTOW, MZFW, max operating level, number of persons permitted, etc., etc., etc....

(f) if you bust the MLW then, I suggest, at law, that is little different to intentionally flying without a valid pilot certificate or rating, taking off overweight, etc., etc., etc...

*********

Now, the whole Certification thing is based on risk, amongst other things.

The reality is that, once airborne, a circumstance may well arise which is associated with a risk environment where an overweight landing is preferable to delaying the landing for sufficient time to burn down to MLW.

The regulatory processes all have rules for the pilot to invoke emergency provisions with the implied right to operate (but only to the minimum extent necessary) outside the normal set of rules. If such a set of circumstances apply then it is appropriate for the commander to consider such an overweight landing.

A responsible and prudent OEM will provide certification-relevant data in the AFM or crew operating manuals for such a circumstance.

A responsible and prudent operator will provide operational guidance in the operations manual for this circumstance. Such guidance ought also provide information to assist the commander in determining whether the particular circumstances might be appropriate to consider an overweight landing.


.. but you don't have any prerogative to land overweight just because you thought it might be a good idea .. or you wanted to get to the pub quicker (although that has some justification after a long day) .. or the toilets didn't work (God preserve us) .. or whatever other trivial reason might pertain.


My views are far from isolated.

That is clear from the several threads relating to this topic. However, such a circumstance is not a necessary and sufficient condition to infer that the view is acceptable from either Regulatory or legal points of view.

From a technical point of view I don't think there is a major issue

In general, from the aircraft side of the house, that probably will hold true.

I don't think you have to be on fire with an engine out before you can do so

Then, where do you propose to draw whatever line ? (This is the line which ought to be in the company operations manual for guidance).

One needs to keep in mind that, if you step outside the "acceptable" boundaries, you can expect

(a) your company to leave you high and dry like a shag on a rock ...

(b) likewise the Regulator ... they might just take your ticket .. and then prosecute you at Law with potential penalties of fine and/or jail time

(c) likewise the Judge .. I shudder when I read, as a lay person, reasons for judgement in some cases. The Law is about procedure and history .. not the lay person's comprehension of Industry-based "reasonableness".

would a 'legally competent' person make the same decision as a competent aircraft Commander?

Very possibly not. However, the concern is irrelevant. The significance of "legal competence" is that such a person might be far better able to comment on the legal significance of Limitations and operation in contravention of such limitations. At the end of the day, should you survive the aircraft event, the legal bits are what are going to result in your being a pauper or able to retire with dignity ...

For those who think that I am being an overwrought wuss ... read up on a few such (or similar) events.

For instance, we have an example in Oz where an apparently professional and responsible pilot recently has been found liable in a Court judgement in respect of a fatal accident several years ago.

As another example, many years ago, a commuter crashed at Sydney. A local airline pilot spent, as I recall, the best part of two days under severe cross examination and all he had done was land during the event in circumstances where he really didn't have much alternative.

.. the list goes on .. and on.

Just had an A330 landing OW after a divertion into BOM due 'All toilets inop'.

.. I think I'll just go and cry into my beer :}... [caveat: I don't know the 330 .. if it doesn't have dump capability then, depending on the circumstances, that situation might well fit in with a consideration of low level emergency warranting an early landing. Interestingly, toilet capability is a practical design consideration for long range aircraft.]

[Quality Time]

JT

.. or the toilets didn't work (God preserve us) .

To be crude.......

What level would the sh1t be at when you reached MLW John?

[john_tullamarine]

Good sir, my comment should be read as being a little tongue in cheek .... I guess that, sometimes, an attempt at humour can fall flat ...

Clearly, with a large aircraft full of passengers of all ages and medical conditions, circumstances may well arise where an overweight landing is reasonable and appropriate in the situation of U/S toilets. I would be less concerned with the social amenity etc., than with consideration of potential medical sequelae.

It is implicit, however, that the normal operational and airworthiness considerations would be incorporated into the decision making process.

However, and more importantly for the discussion topic, this is a perfect example (at least, to me) of why the operator should include OM guidance material on when an overweight landing might be acceptable in lieu of prolonged holding.

The point in question is that it is better for the operator's flight standards and certification/tech services folk to mull over the intracies of such situations around the coffee pot rather than put the commander on the spot ......

[Quality Time]

JT

Surely you just can't write down and cover all eventualities which is why the Commander is meant to be able to exercise good judgement ?

I have definitely taken on board your concern on the legal side of this discussion. I will certainly follow this up in more detail, my concern is that I may want to give up professional flying after I do!

[john_tullamarine]

Surely you just can't write down and cover all eventualities which is why the Commander is meant to be able to exercise good judgement ?

Couldn't agree more.

However, the operator is avoiding its reasonable obligation if it doesn't provide guidance on those situations which are reasonably predictable.

The commander should only have to exercise his/her vast experience and decision making prowess in those interesting, oddball and out of left field events which come out of the woodwork from time to time ... Sioux City and the Hudson are points of note.

The routine bits should be discussed in the OM.

my concern is that I may want to give up professional flying after I do!

As you are aware from our sideline discussions, I am out of the cockpit at present and, when I read some of the things which go on, sometimes I'm not all that keen to get back in.