Burst tyre behind Concorde crash-report

[Irishboy]

<a href="http://uk.news.yahoo.com/020116/80/cpfs6.html" target="_blank">http://uk.news.yahoo.com/020116/80/cpfs6.html</a>

PARIS (Reuters) - French investigators have issued a summary of their final report into the causes of the July 2000 Concorde air disaster, reaffirming their previous conclusions that the crash was triggered by a burst tyre.


But Air France on Wednesday denied a newspaper report that it had been singled out for fresh criticism in a fuller version of the report on the crash which killed 113 people.


French newspaper Liberation reported that the full text of the findings by the BEA aviation security body also noted various failings by Concorde operator Air France, while stressing these were not related to the crash.


The BEA was not immediately available for comment.


An Air France spokesman said there was nothing new in the final version of the report, but that authorities had made various recommendations which had mostly been implemented.


Concorde, the world's fastest passenger jet, re-entered service last November after its suspension following the crash shortly after take-off from Charles de Gaulle airport.


In a summary statement, the BEA confirmed its conclusions from an interim report that the front tyre of the aircraft ran over a strip of metal left on the runway.


The debris was thrown against the wing structure leading to a rupture of a fuel tank and a fire that broke out under the left wing of the aircraft.


Citing what it said was the unpublished full report, Liberation newspaper reported that BEA noted "several dysfunctions" in Air France's operation of the aircraft, "for example the use of certain outdated data in the initial phase of flight preparation and incomplete baggage handling".


"There is nothing new in this report," the Air France spokesman said. "An audit of company procedures was conducted last summer, recommendations were made, and most of those recommendations have already been put in place."

[fox_trot_oscar]

"There is nothing new in this report...."

Exactly - what about all the other supposed contributary factors discussed on this forum from various sources over several months....

<img src="confused.gif" border="0">

[sabenapilot]

They are now all officially classified as rubbish because they have not contributed in any substantial way to the accident.

It's maybe a lesson to those who believe that you can only properly fly a plane if you use the same language as the manufacturer's manual, i.e; English...

Besides, Concorde -as well as Airbus planes- has a FRENCH official operating Manual. For Airbus is even goes so far that the English version is nothing more then just a translated copy! Wouldn't it be time to simplify things and start using French on all Airbus flight decks all over the world? :)

[Bubbette]

The NTSB reports usually include a "survivability" aspect, with suggestions to improve such. Will the final BEA report include this?

[Bally Heck]

The report has yet to be posted on the AAIB site so it may be premature to comment.

News reports however seem to indicate that the conclusion of the BEA is that airline, crew and manufacturer are blameless.

But that Continental airlines isn't.

It will be interesting to see how they explain the grossly overweight take-off, with a tailwind, defective undercarriage and the shutting down of an operating engine close to the ground. (all of course allegedley)

Why am I not surprised?

[B.Navez]

Hello all,

Bally, - this aint no offense, just looking for more info!! - could you post out your sources regarding what you said about the overweight T/O, defective undercarriage and tailwind during T/O? doesnt concorde allow T/O with up to 10Kt tailwind like other airliners? And, the only defect I was aware of was that of a Thrust reverser. Then, last, do you have the adress for this AAIB site you are talking about?

In advance, thanks.

[9g]

More great journalism - BBC News 24 have just reported 'The final report into the crash exonerates the pilots, suggesting even if they had aborted the take off the undercarriage would have collapsed and the aircraft exploded'.
Next time I have to abort a take off I hope that doesn't happen.
They were of course referring to a runway overrun, but come on...

[sabenapilot]

Some plausible answers to those so-called important questions:

-)the grossly overweight take-off:
If I understand it correctly we are talking here of something around one ton of overweight, which is less then 1% of the MTOW! Grossly is not really the correct word. Besides, with average weights for both pax, luggage and cargo, I wonder how many loadsheets showing us as loaded slightly below maximum take-off weight should actually show an overweight situation...

-)a tailwind departure:
Did you really think that as a pilot you are in a position to request for a more favourable rwy on mega-airports like CDG or LHR??

-)shutting down an operating engine close to the ground:
Remember the Concorde has 4 engines, which involves a different philosophy then on the more common twins in case of engine problems. Contrary to twins, here an engine may be shut down in case of a fire as soon as the plane is in a stable flight situation. When the flight engineer closed the engine, this definitely was the case...


I.S.O. asking for superhuman performances, knowledge and insights from the Concorde flight crew in order to fly their plane out of a catastrophe, we'd better spend our time on how it is possible that a US based airline flies transatlantic flights with a plane almost falling apart, parts wich were not even original and thus not certified!

[M.Mouse]

tolipanebas

I am sorry but I have never read such an inaccurate, misleading and dangerously wrong post in a long time.

Not commenting on the Concorde incident because enough has been covered already but according to you it is OK to knowingly exceed MTOW because it is only a little bit over MTOW, take-off with a tailwind because the airport is busy and if you have a major failure it is OK for a crew member to ignore SOPs and do his/her own thing.

I cannot believe you are serious and if I had your cavalier and dangerous interpretation of the procedures for operating a commercial aircraft I am sure my flight management would have a word or two to say let alone my co-pilots.

God help us.

[FrappsZello]

tolipanebas,

With the rubbish you spout, you should not be in charge of a bicycle nevermind a multimillion dollar aeroplane with passengers!

[RatherBeFlying]

Hey folks!

Tailwind up to 10 kt. is within certification parameters for most airliners. And a 1% weight increment requires an increase in airspeeds by the square root of 1.01, not quite one half of one percent -- that would be a bit more than one whole knot.

All of which counts for patoouie when your wing burns off.

Anyway, actions speak louder than words. The fuel tanks and tires have been seriously upgraded since unless you send out sweepers before every Concorde movement, someday there's gonna be debris that you're gonna run over at something like Vr.

[patrickal]

I think the real point that shouldn't be missed is that NO commercial airliner should be taken down by a tire burst. The real cause here is that there was a known problem where a tire coming apart could (and had in the past) cause a serious rupture in a fuel tank. This problem should have been fixed prior to the failure. It follows the same format as the Challenger accident. Every good engineer who knew of the problem felt that it would cause a catastrophic accident sooner or later.....and they were right

[Gunner B12]

The previous thread
<a href="http://www.pprune.org/cgibin/ultimatebb.cgi?ubb=send_topic&t=015105&f=1" target="_blank">Here</a>
discusses this at some length and suggests that it was several tonns overweight for the conditions as well as a lot more. The question still remains;- How come these were glossed over?

It seems to me to be a bit like suggesting a car crash was caused by a burst tyre and ignoring the fact that the car was overloaded and taking part in a high speed chase whilst on fire.

[gordonroxburgh]

For info :

The entire Final report is now available on the BEA's website. The English translation is avilable as a 12Mb PDF.

<a href="http://www.bea-fr.org/anglaise/actualite/concorde-en.htm" target="_blank">BEA Webpage</a>.

Lots of intersting comment; but it does say that the tyre bust was the cause and really not matter what else went on the burst and the resulting fire would have caused the aircraft to crash with the loss of all on board. This is due to the damaged the heavy fire was having on the systems and airframe.

An interting point is noted that if they hade decided to stop when the FE said "Stop" they would still have been at around 70kts. This is what was picked up by the media (BBC) as the report says that they whole aircraft would have been engulfed in flames due to the damage of a crash at 70kts and the level of fire that was present. A figure of 100kts is also talked of for an even later call to stop.

AF procedures for ground ops as expected do come in for pretty heavy pounding.

The report is worth the 12MB download as it does really explain what they understand to have gone on.

[BEagle]

Of course Concorde may plan to take-off with a 10 kt tailwind - but only if the resulting RTOW has been correctly recalculated and proved to be inexcess of ATOW; V1 must also be recalculated.

Those who don't know understand the difference between ATOW, RTOW and MTOW on this thread should refresh themselves about scheduled performance. It is simple enough for anyone to 'back plot' the ATOW and to recompute the RTOW for the conditions at the time with the tailwind. GIVE US THE FIGURES!!

[sabenapilot]

I really would like to meet the first airline pilot who has never done a overweight take-off in his life, be it unknowingly...

Remember that only average weights are used for most items on board, so figures like TOW=125.435kg on your final loadsheet are totally pointless; your real TOW could well be as low as 124.000kg or up to 127.000kg! Now, for flight preparation and planning this is not much of a problem, but if your certified MTOW is 126.000kg, then it might very well be that although according to your loadsheet you are ok to go, you are actually 1 ton overweight!
You see what I mean?

Now, 1.OOOkg may look a lot to most of you, but on a plane weighing 150ton, this is less then 1%!
It's exactly the same as having loaded 3kg too much on a Cessna 150...

Oh, before someone asks, no I have never ever seen a loadsheet where they take a margin on the MTOW to compensate for the inaccuracy of their approximations. If your certified MTOW is for instance 56.345kg, then they may/will load you up to that figure, notwithstanding all inaccurate average values used...

[M.Mouse]

tolipanebas

You are really missing the point.

It is your cavalier assumptions which alarm me.

Yes it is possible that we are heavier than we ought to be on occasions (although checks are carried out to assess the accuracy of using aveage weights). But I would never ignore a weight limit intentionally.

You give the impression you would.

That is plain wrong.

[Capt H Peacock]

tolipanebas

I'm afraid that your assumptions about the tolerances of overweight takeoffs do not apply to large delta wing supersonic transports.

The Captain is on the tape knowingly acknowledging that his aircraft is overweight for both the planned and also the unexpected tailwind takeoff case. He was in possession of all of the facts to enable him to make a safe decision and yet he conciously chose to ignore them.

Had I ever flown with you I would have been very seriously concerened over your attitude to aircraft limitations, but it would appear that we are unlikely ever to do so in the future. "Sabenapilot"

Un rafistolage Francais

[TwoTun]

q'est que c'est le mot en francais pour "whitewash"?

just asking, like.

[poetpilot]

Like many accidents, the cause that precipitated the incident MAY have been containable, were it not for other contributory factors.

Thus....

tailwind (fact)

overweight (fact) (and lets not forget, not only overweight but just over the edge on balance too)

missing spacer (fact)

.......whatever, when it came to the crunch they all added up.

8kts on the nose MIGHT have helped (eg may not have smashed runway light if airborne earlier, may not have even hit metal)

less weight MIGHT have helped, etc etc....

....of course we will never know, they may have made the crash even worse if it had come down elsewhere....

But the Moral? NEVER discount a contributory factor. Whatever the official report says, (& because of the speculation around this, one could be led to suspect that the findings may be biased in terms of shifting blame and liability) no-one can afford to be complacent "cos it's all fixed now".

Please think of that next time you have to weigh up requesting a backtrack against a downwind getaway....

[stuartbaker]

For those who haven't yet got to page 182 of the 12Mb download, the AAIB comments make interesting reading. Doesn't sound like cricket to me:

F-BTSC - 25 july 2000 - 182 -

The UK Accredited Representative has made the following comments on the investigation
conducted by the Bureau Enquêtes Accidents. The section “AAIB Participation in the
Investigation” reflects the concerns with the manner in which the French judicial
authorities affected the technical investigation. In other areas, whilst the UK Accredited
Representative and his Advisors agree with the evidence presented in the BEA report, the
comments represent differences in the weighting of the conclusions.

AAIB Participation in the Investigation

Annex 13 to the Convention on International Civil Aviation (The Chicago Convention) sets
out inter alia the ‘International Standards and Recommended Practices’ for the conduct of
an aircraft accident investigation. The European Council Directive 94 / 56 / EC, which
came into force on 21 November 1994, established the fundamental principles governing
the investigation of civil aviation accidents and incidents within the European Union
States. This Directive embodied the provisions of Annex 13 into European legislation.

The United Kingdom, as the joint State of Design and Manufacture of the Concorde
aircraft, had rights of participation in the investigation as laid down in Annex 13 to the
Chicago Convention and EU Directive 94 / 56 / EC. The United Kingdom appointed an
Accredited Representative and Advisors from the Air Accidents Investigation Branch
(AAIB) to participate in the investigation conducted by the Bureau Enquêtes Accidents
(BEA) under the provisions of the ‘Convention’ and the ‘Directive’. The UK Accredited
Representative also appointed Technical Advisors representing the organisations with
design responsibility for airframe, engines and equipment and who were thus the best
qualified individuals to assist in the investigation. Co-operation between the BEA and the
AAIB enabled the AAIB to make an effective contribution to the investigation.

The French judicial authorities conducted a separate inquiry into the accident in parallel
with the BEA investigation. The manner in which the judicial investigation was conducted
presented major impediments to the AAIB’s participation in the technical investigation.
The difficulties encountered are listed below.

The French judicial authorities did not allow the AAIB Investigators to examine all
items of the wreckage (Annex 13 Chapter 5. 25b) or to participate in component
examinations (Annex 13, Chapter 5. 25g). For example, the judicial authorities:

a. Did not allow the AAIB investigators to examine the strip of metal
which burst the tyre, except very briefly.
b. Did not allow the AAIB investigators to examine that part of the tank
5 lower skin which was found on the runway, except very briefly.
c. Did not allow the AAIB investigators to participate in the
examination of most of the flight deck controls and instruments.
d. Did not allow the AAIB investigators to be systematically involved in
the examination of evidence.

The French judicial authorities did not allow the AAIB Investigators full access to
all relevant evidence as soon as possible. (Annex 13 Chapter 5. 25d). For
example, the judicial authorities:

a. Severely restricted access of Investigators to the crash site.
b. Withheld photographic evidence of the runway surface for 6 weeks.
This evidence later proved valuable in understanding the events on
the runway.
c. Significantly hindered the prompt examination of evidence. This
introduced significant delays to necessary safety actions.

The French judicial authorities specifically prohibited Advisors to the UK
Accredited Representative from participating in the examination of major
components for which the United Kingdom had primary airworthiness
responsibility. (Annex 13 Chapter 5. 25). For example,

a. The judicial authorities prohibited examination by the AAIB Advisors
of the engine bays and wing equipment bays (wing dry bays).
b. The judicial authorities prohibited examination by the AAIB Advisors
of the landing gear selector mechanism.
c. AAIB Investigators and their Advisors were offered access to a
limited number of examinations on the condition that they signed a
commitment to the judicial investigation. This confidentiality
agreement placed unacceptable restrictions on the use of the
subsequent evidence and was therefore not signed.

These obstructions to United Kingdom participation were in contravention with the State of
Occurrence’s obligations under the Chicago Convention (Annex 13). It is also in
contravention of the European Council Directive 94 / 56 / EC which states “investigators
should be able to complete their tasks unhindered”. Furthermore, the restrictions and
procedural delays imposed by the judicial authorities subverted the Directive requirement
that “air safety requires investigations to be carried out in the shortest possible time”.

[Al Weaver]

Re: The information in the above post

&gt;For those who haven't yet got to page 182 of the 12Mb download, the AAIB comments make interesting reading. Doesn't sound like cricket to me:&lt;

Both the AAIB and the BEA investigators were thwarted by the French Judicial authorities, the difference being that the BEA had to adapt to the interference in order to perform their function, while as stated above, the AAIB refused to work outside ICAO annex 13 rules. Incidently both countries were signatories accepting these rules, however that doesn't mean that an individual countries judicial authority can't overrule them when they see fit. That's kind of the way with CVR disclosures as well.

In my opinion, I feel that a thorough investigation has been significantly lessened towards meeting the objective of furthering accident prevention, when a jusdicial authority takes precdence in finding blame rather than causal factors.

The good that came out of this investigation was the willingness of the DGAC/CAA to take airworthiness action prior to the issuance of the faulted report. I can only hope that Continental will prevail in its protestations and any court actions.

[sabenapilot]

The concorde crash was as crash:
-) of a French built plane
-) flown by French pilots for a French airline
-) in France

The UK felt they were also involved because they helped built the concorde, but the French made it clear right from the first day that any British inspectors would be allowed on a courtesy basis only and that their eventual findings would not constitute part of the official report without their agreement.

If an American Airlines Boeing 757 would crash in Miami, I don't suppose the British would want to co-write the official report, would they?

The final conclusion of the BEA report is cristal clear and 100% correct to me:
the doomed Air France Concorde was operated and flown according to normal day to day SOP's as common to Air France's SST fleet.
The principal reason leading to the dramatic events in CDG was the presence of debris on the rake-off rwy, which was traced back as uncertified parts belonging to a Continental Airlines DC-10 taking of only shortly before the Concorde.

All the rest is pure speculation and do not belong in an aviation accident report.

[M.Mouse]

tolipanebas

Your posts are as intolerable as your facts are totally incorrect.

The British didn't 'help build' Concorde it was a JOINT venture between a French and a British firm. No, I am sure the British AAIB would not want to be intimately involved if an American carrier had an accident in an American aeroplane but as the British were very much involved in the design, development, certification and operation of this joint project (Concorde) then I would say that it was technically valuable and morally essential that the AAIB played an active part.

No doubt had this tragedy occurred with a BA aircraft the BEA would have been invited to participate in a British investigation. However they would not have suffered obstruction from the British judiciary. We may not be perfect but we do have a sense of fair play and admit publicly to our failings, often to readily.

Yes the trigger for this accident was a piece of debris. But what is clear, but far from freely acknowledged by those tasked to do so, is that significant other factors were also present that made the situation catastophic.

You clearly have a closed mind and I am afraid your postings add little to constructive debate.
In fact your bigoted opinions serve only to make me angry and I will not be responding further to your questionable postings.

[ 17 January 2002: Message edited by: M.Mouse ]</p>

[sabenapilot]

Well since when are people that stick to the facts considered narrowminded?
Do you really have to believe in weird conspiracy theories, whitewash operations and cover up stories to be labelled openminded?

Let's face it:

if the Continental Airlines debris would not have been on that rwy, there wouldn't have been a Concorde crash eighter, no matter how many contributing factors (tailwind, overweight, CG at the edge, ...) you consider.

However, if you take away all your contributing facts (by using a perfect plane with a perfect crew in ideal situations) but leave the piece of metal on the tarmac, can you guarantee me the rupture of a tyre would not have lead to an accident as it did now?

[N2000]

Tolipanebas, earlier in thisthread you said "a tailwind departure: Did you really think that as a pilot you are in a position to request for a more favourable rwy on mega-airports like CDG or LHR??"...........um yes you are.

If you are unable to take-off from the in-use runway due to a tail-wind, you request a take-off from a runway from which performance is calculated to be acceptable........it may result in a delay (25 minutes recently at a busy international airport)!

Are you a professional pilot or a journalist?

[sabenapilot]

I fly for AirLIb and I can assure you,
at CDG you are NOT allowed to use the RWYs of your choice!

If they have a westerly configuration like on the day of the accident (most common configuration BTW), then there is just no way you can ask for an eastbound departure; all you can do is make a request to change the overall rwy configuration, but unless a sufficient number of requests have been received, no configuration change will be done and all you can do is to eighter take-off from the unfavourable rwy after all or wait till sufficient requests have been made and the request are honoured by changing rwys.

As you can see from the weather at CDG that afternoon, chances were very high that no other plane would have requested an eastbound departure, which in effect would have ment the Concorde flight could have waited indefinitely! Remember the westbound departures are the preferred configuration in CDG as the city of Paris is to the west of the airport and they prefer high flying departing traffic rather then low flying landing traffic over their heads. Besides, a rwy change at CDG normally has consequences for Orly as well...

In short: you eighter go with the tailwind, or you don't go at all! So much as to a free choice of rwy which you are officially intitled to.

[fireflybob]

In that case it's quite simple - if you cannot depart and conform with performance regulations then you either a) defuel and carry out a tech stop for fuel enroute or b) do not take off!

[Dale Harris]

What is this cr@p about "you take what you're given?" To knowingly take off in conditions that do not meet the performance requirements in the given conditions is pretty stupid. Although, maybe in France it's o.k. I have never heard of any airport here (Aust.) refusing a request for runway change based on the captains requirements performance wise. Of course, we're not as busy as CDG and places like that, but I find it pretty hard to imagine that there are no alternatives to accepting what is not suitable. You are after all the "Captain". I'm not suggesting the weight/tailwind problem caused/didn't cause a problem, but as pointed out earlier, it obviously wouldn't help. Anyhow, to say that the piece of metal is the "only" real contributing factor is garbage. Sure, if it wasn't there the plane would not have struck it. If the Captain had requested an appropriate runway for the conditions the plane probably wouldn't have struck it. Kinda like "If my auntie had b@lls, she'd be my uncle" All the factors have a place, and where possible, all must be considered and acted upon.

[Bally Heck]

Gentlemen.

Please let's not start slagging each other off on the grounds of nationality or our opinions. We are supposed to be professionals.

Now. Why have the BEA glossed over the fact that the aircraft rotated far to early (and slowly) probably because the wheel spacer was misssing and it was consequently about to depart from the paved surface.

Possibly as a result of this it was never able to reach V2 and was on a hiding to nothing.

It is possible that if it had been able to climb, it might have made Le Bourget. The burning fuel may not have disrupted the airframe sufficiently to cause a catastrophic failure as the fire was external.

The metal from the Continental thrust reverser may have caused the tyre to burst, but it is a little unfair to blame it for the accident.

It seems to me that as usual there was a chain of events leading up to this accident and the removal of any one of them would have averted it.

Ironic to consider that if they had used the other runway, they would have been airborne well before the wear strip from the thrust reverser was encountered.

[Capt H Peacock]

These words are cut and pasted from the official French BEA transcript from the CVR and so I might make the rash assumption that they are therefore beyond question. I have left the French original intact so that I cannot be accused of xenophobic interpretation.

14 h 13 min 13 s, OMN “alors jauge total carburant moi j'ai quatre-vingt-seize quatre avec quatre-vingt-seize trois pour quatre-vingt-quinze à bord”.

Engineer – Total fuel I have 96.4 with 96.3 for 95 on board

14 h 14 min 04 s, OPL "ZFWZFCG", OMN “alors j'ai quatre-vingt-onze neuf et cinquante-deux deux".

Pilot – ZFW and ZF CofG Engineer – I have 91.9 and 52.2 (%)

14 h 22 min 22 s, Commandant de bord "bon on va faire cent quatre-vingt-cinq cent c'est à dire qu'on va être aux limites …structurales", ….

Captain – We’re going to do 185,500 that’s to the structural limit

14 h 39 min 04 s, Commandant de bord "alors c'est un décollage à la masse maxi décollage ……

Captain – OK that’s a take-off at maximum take-off weight

14 h 40 min 19 s, Commandant de bord "on a consommé combien ?”, OMN "là on a huit cents kilos".

Captain – How much have we used? Engineer – you had 800kg

14 h 42 min 31 s, Commandant de bord "top".

Captain – Go

Add the Zero Fuel Weight given to the Ramp Fuel and you get 96.4 + 91.9 to get 188.3 tonnes

2’12” before take-off the Captain asks how much fuel they’ve used and is told 800kgs, that means the weight that they were working on was 187.5 tonnes

They knew they were overweight even for a still wind take-off (185075 struct.) and they were significantly overweight for a tail wind take-off.

If you are outside the limits for a safe departure you do not go – period. Do we say ‘Oh, but this is CDG they’ll never let us use 08L’ – not if you’re flying with me you don’t.

You are paid to observe all the limits all the time. As you line up you must ask yourself, ‘Is this the right runway? Are my assumptions still correct? Is the runway clear? What am I going to do in the failure case? What’s the situation for a reject?’

If your not asking yourself these things then you do not belong on the flightdeck. This Captain did not, folk hero or no. This accident report does not highlight the opportunities for prevention that were ignored.

BEA - ‘consacré à la prévention des accidents d'aéronautique civile’ – Really?

[ 18 January 2002: Message edited by: Capt H Peacock ]</p>

[wallabie]

Capt peackok

Your rightousness so early in the morning is utterly refreshing. Not on my watch.......etc, stop watching too much TV.
Anyway, I grant you there have been some flaws in the way this flight was conducted.
Excuse a sec, but to our Down Under friends, Melbourne is not CDG and no, you do not get the runway you want just because you're Concorde. That it may have been more suitable to wait ? Maybe or surely or whatever. Would it have made a difference ?
The point is that this accident should have occured in 1976 in Washington and that it didn't because God turned out to be french that day. The circumstances were almost exactly the same regardless of the SOP's.
Had captain Marty waited at the treshold to have the right weight and everything, he still would have had a tyre bust hitting that piece of falling apart Continental DC10, it would still have burnt in the same way and 1 ton less or not, it would have been lost due to the uncoverable damages to the aircraft. That's an undisputable fact.
That some of you want to get rid of their frustration trashing Capt Marty's crew and the country, airline and culture they belong to, will, I hope, make you feel a lot better about yourself but will not alter the facts I just mentioned.

Peackock, if you think this aircraft would have made it the way it was burning, remind me to stay home on your next shift.

[Dale Harris]

Sorry Wallabie, maybe you misinterpreted my post. I did not suggest that "Because you are Concorde" you should get whatever you want. My statement is applicable to any aircraft and any captain. You do not accept a clearance, TOW, loading C of G or any other thing that may put you at greater risk than necessary. I also stated that the loading/performance discrepancies may not have caused the accident themselves. I don't think they "caused" the accident. But there is no doubt that all contributing factors however small must be taken into account. As stated earlier, interesting to ponder what an 8 knot headwind instead of tailwind may have produced. Just because an aircraft, (any aircraft) has "managed" to make it before in similar conditions does not mean it's a good idea to repeat the excercise does it?

[No Mode Charlie]

Cewl, loads of people blaming eachother again for being bad pilots and all sorts. Maybe I'll join in <img src="cool.gif" border="0">

Anyway, on the overweight, outside performance envelope T/O. I'd have to stay on the ground too! And if you seriously consider doing your take off performance calculation and then going anyway because otherwise it might be inconvenient then why do the math at all? Just go the end of the runway, wich ever one someone feels like, give it full whack on all four and start pulling when it might be somewhere close to Vr. Sorry, that does not sound like a good plan to me!

[M.Mouse]

wallabie

With respect I think you are missing the point. What alarms many of us is that the investigation appears to be paying little other than lip service to some very serious questions.

I am sure no pilot reading this forum is intending to besmirch the names of the late crew but it is incumbent upon any investigation to examine all the facts. I wish I could say I feel the facts had all been properly aired.

Capt. Peacock quotes some facts that are known but appear to have been given little consideration when most right thinking pilots are alarmed at what seems to have been some quite extraordinary decision making (except to tolipanebas who feels it is OK to ignore SOPs and limitations).

Despite the questionable findings of the report raises let's hope that some very fundamental lessons have been learned.

[Capt H Peacock]

Wallabie, encore une fois

I, like all others, feel deeply for the loss of the individuals concerned in this tragedy, but as pilots we are required to look at cold, hard facts and deal with them dispassionately. We have to ask awkward, searching questions of all those involved in any incident. That is how we will avoid such accidents in the future, and how we as professional aviators will learn and improve our skills.

The mechanism of breach of the fuel tank was hydrolastic shock caused by the fact that the aircraft had been over-fuelled. This resulted in the wings being inflated and so compromising their structural integrity. The capacity of the aircraft in question is stated in the BEA report as 94470kg. The engineer read out the fuel on board as 96400kg which is 1930kg more than the certificated maximum fuel load and 2437 litres of extra volume to fit inside the wings.

Such procedures are not in use by other operators of Concorde, and therefore the incident at Washington is unlikely to have resulted in the same outcome. As it happens, as a result of that incident, modifications were undertaken to all Concordes on that operator’s fleet to prevent a reoccurrence. Evidently the Concorde at Gonesse did not have these modifications fitted. In the rare cases where extra fuel is needed, then other operators load special high specific gravity kerosene.

If I were a fellow countryman aviator of yours, I would be deeply offended by your assertion that any pilot would deliberately ignore the certificated maximum parameters of their aircraft. Je suspecte, Monsieur, que vous parlez de vous-même.

[Harvy]

The high TOW may have caused the tires to burst but they have done so before several times on concorde and the fact that this didn't cause a fire before is amazing. This was an accident waiting to happen that was ignored.

[NW1]

Capt. PCock - I've tried to stay out of this debate because there really is nothing to be gained except hightened tensions by the to-ing and fro-ing on the performance issue. I entirely agree with you that no aircraft should be operated outside of limits and that is that - there can be no disagreement on that score. However, I do not believe that the outcome would have been any different in this accident.

What is important, though, is that you get your facts right. You state that [quote]..the aircraft had been over-fuelled. This resulted in the wings being inflated and so compromising their structural integrity.<hr></blockquote>Not so - the Concorde's fuel capacity is given as a function of the fuel's SG (from my manual - at .801 it is 95930kgs) and there is an extra load of up to 1200kgs which may be taken on top of that using a special, certified, procedure. BUT these figures are not limitations - they are capacities given as guidelines for planning - the actual limit is when the refuel valves trip off, there are no operational limitations here and talk of wings being "inflated" by "over-fuelling" is misleading.

The Washington incident is a red-herring because the puncture there was caused by a failing wheel-rim - a small metal fragment is very different to a comparatively huge piece of rubber. The leak from the small hole was bearable - a very different situation in cause and effect to Gonesse, and nothing whatsoever to do with fuelling procedures. A different sequence of events entirely - and as I understand it down to a faulty batch of wheel rims which was corrected. (interesting to note that to this day a Concorde fuel tank has never been punctured by tyre debris).

[quote]Such procedures are not in use by other operators of Concorde, and therefore the incident at Washington is unlikely to have resulted in the same outcome.<hr></blockquote>
There are no significant differences in refuelling procedures between operators, and the Washington incident was very different to the Gonesse accident for the reasons I outline.

[quote]As it happens, as a result of that incident, modifications were undertaken to all Concordes on that operator’s fleet to prevent a reoccurrence. Evidently the Concorde at Gonesse did not have these modifications fitted.<hr></blockquote>
The modification to the water-deflectors you allude to would have been irrelevant in Paris. They are designed to contain a failing water-deflector, and not all operators fitted them, it is thought now that the mod. itself is just as likely to cause damage as the deflectors (which are of light-weight composite contruction) and have been deleted.


[quote]In the rare cases where extra fuel is needed, then other operators load special high specific gravity kerosene.<hr></blockquote>
It is certainly not rare to need extra fuel :) - but believe me, we have no capability or availability to demand "special high SG kerosene" we are stuck with what the bowser guy tells us and fit in with that for capacity, CG and takeoff loading calculations. I could explain it all to you, but you would definately fall asleep (in case you haven't already if you've nmade to the end of this message!!!)........zzzzzz

[NW1]

Harvy,

[quote]The high TOW may have caused the tires to burst<hr></blockquote>
No - it didn't. The metal fragment did.

[quote]but they have done so before several times on concorde and the fact that this didn't cause a fire before is amazing.<hr></blockquote>
No, it isn't. Damaged tyres have never punctured a Concorde wing in the history of the aircraft. Unlike some other types. The Gonesse accident was a combination of many incredibly improbable circumstances, and the chances of even that almost impossible chain of events recurring has been eliminated.

[Harvy]

Fine the TOW made little/no difference but this was a problem that has been around for ages and was not addressed before lives were lost. See the link below if you haven't already. Tires burst plenty cause more than enough damage to warrant concern.

<a href="http://aviation-safety.net/cgi-bin/dbsearch.cgi?concorde+search+retrieve+&&1-17&Event=burst%%%%dm=Line+cs=No+em=Yes+ob=Key+dfd=Yes" target="_blank">aviation-safety.net previous concorde incidents</a>

[ 18 January 2002: Message edited by: Harvy ]</p>

[NW1]

Harvy,

"This" was not a problem that had been around for ages. "This" was a problem which had never surfaced before. It was a problem caused by a chain of many highly improbable events, starting with an incredibly unfortunately shaped strip of titanium which stripped the outer case off a tyre in a manner never seen before let alone forecast, leading to the loss of the aircraft. This had never happened before, and probably never would again irrespective of any modifications.

Each one of the indentifiable links in the chain have been addressed (their luck never recovered from encountering the strip: the mode of the fuel tank hole creation - the location and size of the hole etc. all were worst thing, worst time, worst place events)- yes: because a fatal accident occourred, but what happened at Paris that day was unique in Concorde's history. Claiming from your armchair that it was obvious or predictable as you do is facile and misleading.

To repeat: debris from a Concorde tyre has never puntured a fuel tank; it was an unprecented and unforcastable accident. All that web link you quote proves is just how resilient the Concorde type is to tyre failures.

[Capt H Peacock]

NW1 you have me at a disadvantage, Sir. I do not have the manuals and I do not operate the Concorde. My suspicions are raised because the report quotes the maximum capacity in litres as 119,280, with an approved overload of 1,630 litres giving a maximum of 120,910 litres.

The report quotes that standard Jet A1 with a sg of 0.792 was used to fill the aircraft, and the engineer quotes the gauges as reading 96.4 on the ramp before departure. 96.4 tonnes at 0.792 gives 121,717 litres, which is 807 litres or .807 cubic metres over the maximum capacity, hence it was overfilled.

The work that was done by the manufacturers on hydraulic shock quotes the rupture mechanism involved in a full tank with no air gaps. With this fuel load I suggest that not only was there no air gap, but no surge space available.

My information on fuelling came from an old acquaintance in Shell who described the procedure for high gravity fuels. Perhaps it was during development flying or something. You are probably well aware that jet fuel can come in a range of densities between .775 and 0.84, but DEF STAN 91-91 fuel which is the British standard for Jet A1 comes in at 0.793. However, higher density fuels, with a higher calorific value are available due to a higher napthalenes and aromatic content. These fuels (commonly 0.808) enable higher fuel loads to be carried and thus longer range flight. They tend to be less environmentally friendly with more smoke and more emissions.

If any of my assumptions about Concorde operations are incorrect, then I gladly give way to you. Perhaps in your rather unique position, you might tell us what maximum take-off weight you would use for CDG 26R with 080/09kt and 19ºC. Would you have operated your Concorde at that weight, 187.5 tonnes?

[the_fat_maintroller]

-------------------------------------

BUT these figures are not limitations - they are capacities given as guidelines for planning - the actual limit is when the refuel valves trip off, there are no operational limitations here and talk of wings being "inflated" by "over-fuelling" is misleading.
--------------------------------------

My understanding of 'high level increment'(HLI) refueling as quoted in the UK operators refuel procedure, does allow for extra fuel to be added after the refuel valves have shut normally.
From memory the procedure was to individually open certain tank refuel valves but jumping a connector on the Fuel Qty Cmptr to earth.
The refuel manual then gave a specified qty of litres than can be added to that tank. Effectivly each tank was topped to 'FULL'.
This was an approved procedure, I am no longer involved in the Concorde,so can not comment if it is still used, but was most certainly was used especially on BGI sectors.
The refuel pad used by the ground engineer had columns for recording HLI refuel. <img src="eek.gif" border="0">

[NW1]

Capn. PCock-
I don't mean to hold you to any disadvantage <img src="smile.gif" border="0"> - just to address a few incorrect assumptions you made with no disrespect at all intended. Being current on the type obviously helps!!

The fuel vent system on the Concorde cannot be "filled" because it terminates in a scanvenge tank which contains a pump which pumps either into tank 3 or else to atmosphere - either way the vent system is kept clear. It may be that the hydraulic shock effect would not have taken place if tank 5 had been less than full (speculation, obviously), but the only time this would be the case would be on a very short trip indeed. Concorde is by no means the only airliner to roll with more than one tank full - but as I say there is a proper vent system similar to most other types and there is no defined limitation on the fuel level. (other than the scavenge pump dumping excess onto the rear cargo loaders <img src="rolleyes.gif" border="0"> )

Out of interest, at the SG of 0.792 you mention the quoted max. tanks figure is 94740 - add the allowable 1200kgs of "HLI" (the "extra" fuel I alluded to) and you get a planned max fuel of 95940 - the allowable 2% guage inaccuracy alone would take that to 97850 let alone any small variations in actual SG, so no: from my experience I would not say the fuel quantity itself on board was questionable and certainly not out of limits (there being no operating limits on fuel level). As for the performance consideration - to answer your question - no pilot may take off overweight simple as that. Even ignoring T/O performance issues the max. structural TOW is 185,070kgs but my own opinion is that this had no effect at all on the outcome. Once tank 5 had a big enough hole to lose its 7 and a quater tonnes of fuel assymetrically at 100+l/sec from the left wing I suspect it was game over at any weight and the devastatingly destructive fire sealed it.

One last point - I gather that detailed analysis of the FDR showed that local W/V at lift-off was actually zero - the tower quoted 080/9 was probably a temporary change local to the anemometer, but as I say I think this is a detail which had no bearing on the accident. It is important that the root cause is addressed (it has been - most thoroughly) but, like you, I would stress that it certainly isn't on to pay lip service to limitations such as RTOW - its just that this issue in this case was irrelevant in that it had no bearing on the outcome, IMHO.

[NW1]

Hi Maintroller,

You're absoultely right about HLI fuel. I alluded to it but didn't want to cloud the issue with detail. It is a fully authorised way of adding 1200kgs to the fuel load by changing the fuel shut-off system. But it doesn't compromise the vent system, and it doesn't "inflate" fuel tanks - the implication that the fuel tanks were being blown up by "overfuelling" them was misleading. There is no operating limitation on the fuel system to be exceeded by loading fuel.

You see many 747-400's with fuel venting from the wingtip vents as they taxi round corners on a long range sector. With fuel loads in excess of 90 tonnes on any type it takes very small percentage point variation in temperature, SG or gauging accuracies to result in a bit of harmless venting. The fuel systems on airliners is designed to cope - and Concorde is no exception, as I pointed out to Capn. PCock...... hope this helps.

[wallabie]

Pee Cock mate. I'm so wounded by your remarks !. .Specially the last one. How can you be so mean and cruel !!? Ouch !!. .If you're going to use French, at least do it properly. Your command of the language is an absolute shocker. Stick to English and I suggest you read what I said again as there most obviously was a lot of line distortion on the way to your brain.

NW1 comments, I hope, will maybe persuade you of what the real issue is and that's not paying a lip service to SOP's. If not, no one can save you.. .You've got your booking at the loopie farm.

[Bally Heck]

Does not the report fail to answer a number of crucial questions?

For example, the report findings include the following:

"The marks on the runway show the aircraft deviating to the left of in relation to the runway centreline."

In fact, earlier in the report is states the aircraft was 22.5 metres left of the runway centreline. Runway 26R is 45m wide!! There is a fairly simple calculation there that shows the aircraft was about to leave the paved surface. There is no way the aircraft should have been there with the damage it had at that point suffered unless the pilot mishandled it (unlikely) or perhaps the missing spacer on the left main landing gear bogie?

Yet the report states:

The spacer on the left main landing gear bogie had not been re-installed during. .replacement of the bogie on 17 and 18 July 2000. This omission did not contribute to the accident.

Why did they not test the effect of a missing spacer on a bogie with a disintigrated tyre?

The conclusions also state:

"The crew began aircraft rotation at the same time, at a speed of 183 kt, 15 kt. .before VR."

No crew would begin rotation this early without a compelling reason. Perhaps the reason was that he was about to depart from the paved surface, and according to a number of reports which have not surfaced in the BEA report, was heading towards a B--747 at the holding point for 08!

As a result of the early rotation, the aircraft never got anywhere near to the V2 of 220kts. The best they managed was 208kt and they got airborne at 201kt, 2kt above planned Vr I don't think many aircraft will catch up with their planned performance if they have a failure after V1 and get airborne twenty knots too slowly.

Why is there is no analysis of this in the report? They say

"Because of the lack of thrust and the impossibility of retracting the landing gear,. .the aircraft was in a flight configuration which made it impossible to climb or to gain speed."

And yet with such early rotation, they would have had a serious problem climbing even with the landing gear retracted. In fact first segment climb is scheduled with the landing gear down!!

This is such a detailed report with for example a full page devoted to the aircraft air conditioning system! And a couple of lines devoted to the aircraft being twenty knots too slow to ever have a hope in hell of successfully climbing away from an engine failure!!!

[NW1]

Bally - I personally am sure that the cause of the accident was as stated: the metal FOD -&gt; unique tyre shred event -&gt; unique ('till then) hydraulic shock event -&gt; massive hole -&gt; massive leak -&gt; massive fire was all as the analysis revealed, and that action has been taken to prevent its recourrence. I do agree that the deviation and u/c spacer issue is puzzling and not covered as deeply as you'd expect in the report.

But even if they'd managed to reject the takeoff and stop within the ED / land at Le Bourget / climb away at V2: with most of the back end (including flying control surfaces) burning away -I think the end result would have been little different. I feel that the focus of the accident report has quite rightly been on the CAUSE(S) of the accident so that it has been prevented from happening again.

That's what matters, IMO. Perhaps all airliner accidents should receive such thorough attention: grounding, diagnosis, corrective action, re-instatment?

[Bally Heck]

NW1

I think you are probably correct that in this case they were on a hiding to nothing....probably.

But suppose the tyre had failed and taken out an engine with no fire. They would still have crashed because the aircraft was too slow to achieve V2 with reduced thrust. The massive drag of a slow delta winged aircraft would have ensured that they could never have climbed, fire or no fire.

If they had climbed away they might have made Le Bourget or they might have crashed on clear ground saving some lives on the ground. The increased speed may have blown the fire clear of the airframe!

I'm not convinced that the crash was inevitable if the aircraft had taken off at the correct speed.

I know there are a lot of ifs and maybes there but why were they not investigated. Could it be that it easier to blame another airline's maintenance practices?

Surely all these issues should be addressed in a thorough report.

[NW1]

Bally,

We are getting a little off-thread and into speculation here (that's why I tried - but failed (!)- not to dive in), but: the Olympus has shown itself highly resistant to FOD. In fact there are many instances of it swallowing far more than a chewed up tyre without a hiccup. During the post-crash research into the effects of fuel ingestion on the engine at takeoff thrust (including full reheat) they surged the test engine so badly during a particularly extreme "to destruction" experiment that the compressor stages were written off (I saw the video - it was very impressive!). They then put the damaged engine though many (about 20 from memory) start / takeoff / accel / decell / shut down cycles including fuel ingestion with not even a loss of thrust or a raised EGT - surprising even RR I think.

But even if it did, a propos your supposition about delta-wings, a Concorde three-engine climb out at max TOW shows a positive rate of climb right down to V2 minus 23 knots (incidentally, that figure is only 18 knots on a subsonic a/c to BCARs). So no, I don't agree with your comment about attaining the right speed (although it certainly and obviously made the situation more grave, it was critically grave in the first place) - I believe that aircraft crashed because it was so massively systemically damaged and was being consumed by an unprecedentedly huge fire.

[quote]I know there are a lot of ifs and maybes there but why were they not investigated. Could it be that it easier to blame another airline's maintenance practices?<hr></blockquote>If you mean AF's maintainance, I don't believe that was the claim or that it was indeed the fault. If you mean Continental because the metal dropped off their jet - I don't think that they are being made convenient scape-goats. Sure, if that metal strip hadn't been deposited then the crash wouldn't have happened, but that doesn't mean the blame and corrective action stopped there - the many links in the chain of events have all, at huge effort and expense, been addressed even though it was an accident which occoured in the face of infinitessimal odds in the first place.

Edited for typo...

[ 21 January 2002: Message edited by: NW1 ]</p>

[Bally Heck]

NW1

Your knowledge is impressive, and I will not take issue with any of your points. However it still begs the question, why were these points not clarified by the BEA.

One little quote from the report.

"a gap of twenty-two metres between the aircraft and the runway centreline."

Which bit of the aircraft for goodness sake! The runway is only 45m wide. Does that mean the entire aircraft is on the grass? Or half the aircraft? Or none of it? They don't specify a reference point on the aircraft! This is a very amateur bit of investigating.

There is evidence that at this point the Concorde was heading towards an AF 747 (with the French president on board) and the captain had no choice but to rotate early.

If this is correct, then the aircraft was effectively out of control before getting airborne. This is a very serious issue and the accident report completely fails to address it or to make any recommendations to prevent it recurring. So due to the lack of attention to this very serious loss of directional control, I am left asking myself, was it due to the lack of a spacer in the undercarriage assembly, or was there another reason which has yet to be discovered. Is the next Concorde which experiences a tyre failure also going to veer of the runway?

The major problem I have with the report is that the French authorities were obstructive towards the AAIB. This is just begging for accusations of conspiracy. In my view, you would only try to hide things if you were afraid of what might be found or wanted to present a report which suited political ends rather than flight safety aims.

[Evo7]

NW1

Thanks for taking the time to post. <img src="smile.gif" border="0">

[Al Weaver]

&gt;The major problem I have with the report is that the French authorities were obstructive towards the AAIB. This is just begging for accusations. . of conspiracy. In my view, you would only try to hide things if you were afraid of what might be found or wanted to present a report which suited political ends rather than flight safety aims.&lt;

I don't think that you have this all right. It was the French judicial system that caused the problems and not the French BEA investigators. It would be quite a stretch to accuse the jusdicial system of conspiracy when their objective was to find culpability to satisfy their constituents.

In the end you are quite right that this type of behavior is more politically suited than serving the objective of flight safety. On the other hand do you suppose that safety has not yet been achieved?

[Bally Heck]

See my previous post Lompaseo. The crew lost control of the aircraft before it got airborne. The investigation has failed to recognise this as even being a problem far less finding reasons for it in order that future crews should not have to face similar problems.

[Capt H Peacock]

NW1, thank you for your comments from what is clearly an experienced view point. I accept your explanations of the capabilities of the tankage, and the ability of the fuel vent system to cope with over-pressure. I also am prepared to entertain that at the maximum fuel load, and the limit of gauge tolerance, a fuel indication of 96.4 is consistent with normal operation.

Let us then move away from the minutiae of the fuel system and settle perhaps on a maximum certificated fuel weight of 94.74 tonnes. The zero fuel weight is quoted on the CVR by the crew as 91.9 tonnes, and we are able to deduce from the tape that 800kgs were burnt on the way to the runway. That gives a working weight at the moment of line up of 185,840 kgs which is still over the structural maximum certificated weight of the aircraft of 185,075 kgs.

The events that followed during the take-off roll are notorious history, and I shall not discuss further here. The common factor in all accidents is a chain of events that leads to a catastrophe. Breaking any one of those links in that chain is the key to averting disaster.

In the light of what is given to us in the officially documented factual account of this terrible disaster, can we identify any point at which the crew might have made an informed and routine decision not to proceed? In my humble opinion there is, and I would put it to you that that decision should have been made. Without discussing the tragic mechanism for the loss of the aircraft, the whole thing should have been stopped before it ever began.

Wallabie, you have yet to add one single, reasoned argument that is germane to this discussion. Your tirade of personal abuse has no place on a professional pilots forum. My knowledge of French may not be perfect, but I would never have had to learn it if I did not operate frequently into parts of the World where it is routinely used for the control of air traffic. My exchanges with you are at an end. Au Revoir – Is that alright?

[sabenapilot]

There we go again... <img src="frown.gif" border="0">

after seeing this discussion moving away from needless hairsplitting over a few extra knots of wind and a few extra kilograms of fuel thanks to some technical day to day insights on Concorde, some of us apparently are going to refocus on the supposed overweight of Concorde once again...

. .According to some precise calculations made by our friend here above, the weight at the moment of line-up was 185,840kgs which according to him is still over the structural maximum certificated weight of 185,075 kgs by a full 765kg... <img src="eek.gif" border="0"> . .I do not feel the need to check these figures, as I trust they are 100% correct, but allow me to make some remarks to them:

-) The weight at line-up is found by deducting 800kg from the rampweight that day. Now, we already had the discussion about how (un)accurdate this rampweight is (an error of up to 3% is nothing unusual), but for which I have been called all sorts of names. . .Nevertheless, I dare to ask if we are really going to do the same thing once again by giving too much importance to the accuracy of given values like that of the 800kg of fuel? I mean, first of all, how accurate is the readout of a fuel dial on Concorde (2% seems acceptable), and secondly, is it purely coincidental or did the F/E rounded off the fuel burn to a value ending on dubble zero? You see, substracting something with a margin of error of at least 2% from something with a margin of error of 3% and then saying oops, we are 0.4% over the limits is just b******t; any physician will tell you the total margin of error in such a case is even more than 3%. In other words, Concorde could very well have been 0.4% overweight, or even 3%, but she might as well have been a full 3% below her max take-off weight!

-) We really have to start taking max. take-off weight (MTOW) for what it is; an indication of a limit rather then an absolute limit. The best prove that this is also the way manufacturers want you to think of it is found in their winter operations. As you maybe know winter operations require the removal prior to departure of all snow, ice and frost on aerodynamic surfaces like wings and tails, but most planes are certified to take-off with ice on the fuselage. Now, if we accept that ice deposit on the fuselage has a weight too (nothing unreasonable, is it?), then it is clear that any MTOW-departure under these icing conditions is actually nothing more than an overweight departure because there is no correction made on your loadsheet for the additional weight of the ice! Yet, although the mathematical outcome shows you an overweight situation, this is in fact OK for manufacturers like Airbus and Boeing. . .Now, if it is apparently OK to take-off with let's say MTOW + 700kg of ice on the fuselage, then are we really going to fool eachother by sitting at the holding point burning of an extra 700kg of fuel for 10 minutes?

You see, my moint is:. .you have to make a distinction between the planning and the operations phase of a flight.. .In the planning phase everybody should stick to all kind of limits, and if you exceed them by one knot, one feet or one kilogram, you should do something about it. . .However, the general philosophy is slightly different when in the operating phase (i.e. crew on board); knowing that all given limits still leave you with a considerable margin, then it is perfectly ok for a captain to use a small bit of this margin to stay in line with the economical criteria set forward by his company. This decision taking process of how much of a margin can be is used is called captaincy and comes not from books, but from experience. It differs from plane to plane and from pilot to pilot of course: I have seen guys with big margins (taking of with tailwinds of 10 knots when perfo was calculated with no wind) and guys with very small margins (asking to recalculate take-off data for an intersection take-off on a rwy you could reland on), yet I'd say 0.4% overweight certainly is no big deal...

[Dick Deadeye]

Sabenapilot your comments are the dumbest I've seen on this website.

You have NO idea what you are talking about so until you do shut the f$ck up. <img src="mad.gif" border="0"> <img src="mad.gif" border="0"> <img src="mad.gif" border="0">

[sabenapilot]

And your point is?

Oh well, none I guess, since you can't even spell my name correctly.... Suffering from dyslexia? :)