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TUI planes takes off 1200 kg overweight after software error

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TUI planes takes off 1200 kg overweight after software error

Old 9th Apr 2021, 04:33
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TUI planes takes off 1200 kg overweight after software error

Tui plane in ‘serious incident’ after every ‘Miss’ on board was assigned child’s weight Service from Birmingham to Majorca took off with less thrust because pilot thought it was 1,200kg lighter

An update to the airline’s reservation system while its planes were grounded due to the coronavirus pandemic led to 38 passengers on the flight being allocated a child’s “standard weight” of 35kg as opposed to the adult figure of 69kg.
The Guardian, 9 April 2021 (can't post URL sadly)

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Old 9th Apr 2021, 05:58
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Here it is:
Grauniad: TUI incorrect weight
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Old 9th Apr 2021, 06:26
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Yep been done before
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Old 9th Apr 2021, 08:07
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Wouldn’t date of birth be a better data point to determine whether someone is a child? And is 69kg really the average adult weight in the UK?
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Old 9th Apr 2021, 08:16
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I know what you mean but it'll be an assumed Female adult average weight ......and since you asked...


See Table 4.17 on page 87.

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Old 9th Apr 2021, 08:17
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Given the size and obvious weight of some of the rucksacks regularly being hauled on-board, perhaps a more accurate estimate of hand-luggage weight :-)
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Old 9th Apr 2021, 09:44
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Not much (thankfully!) in the AAIB bulletin for April as no flying - once Commercial and GA returns to normal levels the monthly bulletins will be the size of the yellow pages!

Actual AAIB article for this one - https://www.gov.uk/aaib-reports/aaib...g-21-july-2020.

"Subsequent use of the actual takeoff weight for performance calculations showed that all departure airspeeds should have been one knot greater than those used on the incident flight, and the thrust required should have been 88.9% N1 compared to the 88.3% N1 set on the incident flight."

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Old 9th Apr 2021, 10:36
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Well in the past, our aircraft; (extinct Luton based airline), were sometimes heavier than we thought, because we used standard passenger weights. Once in the cruise, I used green dot to work out the actual aircraft weight and it was sometimes 2 tonnes above what we had calculated at the gate.

One season, we subbed for another Luton based airline, and their standard weights were higher - 93 kg for a male, whereas we used 88kg - I cannnot recall the female figures.

And yet there was a hell of a fuss if the wrong catering weights were used - even though that only made an error of a few hundred kilos.
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Old 9th Apr 2021, 10:48
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I suppose this is classed as a miss(hap)?

But seriously just as well they weren’t performance limited. I’ve often wondered how accurate the weights on a load sheet compared to reality. On a previous type the relation between Vref and weight varied by about 1 knot per three tonnes.
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Old 9th Apr 2021, 11:21
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I always assumed that we were at least a ton heavier than the load sheet suggested., just look at the size of the passengers boarding (and the amount of cabin baggage)
Management will always want you to reduce to the limit but I always kept a little in hand, eg using performance from an intersection, then departing from full length.
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Old 9th Apr 2021, 12:48
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Planes are regularly overweight. When departing at MTOW do we seriously think the average weights used are accurate for people or bags?
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Old 9th Apr 2021, 13:28
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Relatively speaking the error was minor as 1200kgs would be less than 2% of the MTOW, though obviously it shouldn't have happened and procedures need to be put in place to ensure it doesn't happen again.

Narrow bodies are much more forgiving of incorrect take off calculations than wide bodies, particularly when operating at airports designed to accommodate the larger variants, though a South American cargo B727 was lost when all the holes in the Swiss cheese lined up. https://en.wikipedia.org/wiki/Aerosucre_Flight_157

Wide bodies are a different ball game with numerous accidents and near disasters happening because of incorrect take off data, the recent SAA A340 comes to mind.

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Old 9th Apr 2021, 16:23
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If the aircraft is overweight it will show up in the fuel burn. At my airline we almost always underburn verses the flight plan so I suspect the weights are pretty accurate. 69 kilo’s is probably about 15 kilos short of the true average female boarding weight. The US uses 84 kilos for female winter weights. 79 in the summer.
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Old 9th Apr 2021, 16:48
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Reading the report - it wasn't overweight, the actual load showing they were over 12T below MTOW.

From the AAIB report

Whilst an incorrect takeoff weight was used for aircraft performance planning, the thrust required for the actual TOW and environmental conditions (88.2% N1) was marginally less than the thrust used for the takeoff (88.3% N1). This meant the safe operation of the aircraft was not compromised.
Which in my mind reads, nothing to see here, move on...
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Old 9th Apr 2021, 17:57
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To be honest, I am actually amazed that anyone even noticed.
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Old 9th Apr 2021, 20:50
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Or its the result of a sound safety culture that means the most inconsequential of events is treated with the appropriate level of seriousness, introducing new procedures and accountability which go on to prevent further events reoccurring.
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Old 9th Apr 2021, 21:13
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Anyone able to comment on why narrowbodies are less susceptible to 'overloading' that widebodies ? Is this to do with reynolds number as weighrs and scale goes up?
I clearly remember a colleague routinely overloading an 5000lb aeroplane by 500lb or more, 10% and scoffing at the idea that it was unwise. (US pilot). Certainly the Caravan didn't show any distress though runway analysis (or common sense) wasn't involved.
Later I flew the 146 where afair weights for performance were pretty carefully defined and was astonished on conversion to the 737 classic where Boeing's performance book figures made little issue of half a ton or so either way. At that point massaging the loadsheet to comply with individulal kilos was thought more important than whether the aeropalne could take off, reject or land at the calculated weight by a factor of 500 or so which isn't very rational.
Structural reasons are a different matter; I'm curious why widebodies (does that actually mean 'heavies'?) are more susceptible to overloading than other(lighter/smaller) ones?
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Old 9th Apr 2021, 22:33
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If I recall correctly the FAA mandated an increase in the average weight estimate per passenger as the rate of obesity increased in the USA.

At one point/once upon a time checked luggage was weighed as it was checked in.

When airlines started charging extra for checked luggage rather than carry-on, presumably they lost track of however many extra pounds people would stash in their carry-on luggage to avoid getting charged an extra $60 or whatever.

I know that I try to carry everything I can with me, if only to avoid the concern about it getting lost at a transfer point, or to skip the wait in the baggage area.

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Old 9th Apr 2021, 22:50
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Is it a “software error”? Or is it a software “user error”?
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Old 9th Apr 2021, 22:53
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Dannyboy - Quite agree that appropriate action is taken... But it has, hence my comment (probably stems from the fact I don't really like the title of this thread - The aircraft wasn't overweight but had 1200kg unaccounted for).

meleagertoo - Just in my experience and I don't call this 'overloading', but incorrect performance. Most shorthaul airliners flying out of moderate to large runways are frequently performance limited by the climb, not the runway length. Thus if a performance error occurs, usually there's little perceived problem due to both engines (hopefully!) running thus no actual issue with the climb segment. Going to longhaul aircraft, the performance is quite often runway distance limited - stop margins of 0m are frequently seen in the performance software despite moderate weights and 4km runways. Thus if the performance is run slightly incorrectly, then the perceived problem of the end of the runway is very apparent.
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