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TheSonntag
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Overloading Airliners - easily possible?

Mon Mar 08, 2021 3:04 pm

In General Aviation, it is quite easily possible to fly an overloaded airplane. Especially in typical trainers like the C172, if you put 4 people in it and fill up the fuel, the plane is very soon above the maximum take off weight of 1158 KG.

Reading accident reports, it gets clear this is not that uncommon (while illegal), unfortunately.

While illegal and dangerous, it is, unfortunately, quite easy. There are not sensors which could warn the pilot, so it is the pilots responsibility to calculate correctly. And sometimes it goes well, and sometimes it does not.

How is this with airliners? Obviously, IT equipment and dedicated personnel help, but do the airplanes actually measure their own weight? Is it possible to overload modern airliners without anyone noticing, or would this trigger warnings?
 
GalaxyFlyer
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Re: Overloading Airliners - easily possible?

Mon Mar 08, 2021 3:23 pm

They do t measure their own, the dispatchers or load planners use software that is integrated with flight and performance planning to arrive at maximum permissible weights and balance. There have been a few instances of missentering the data into the FMS and a close call. EK at MEL in an Airbus years ago, IIIRC. I’ve questioned C-5 loadmaster weights and CG a few times and found errors, all manual calculations
 
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T18
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Re: Overloading Airliners - easily possible?

Mon Mar 08, 2021 3:38 pm

Our FMS will return a clear message if the weights entered put the a/c over MTOW or Max Ramp weight. However I have had flights that left the gate over ramp weight before, not sure how the crew did that one. It also seems to be common these days that the station will put an absurd amount of cargo/baggage on board and put us over our MTOW forcing either a burn off of non required fuel or removal of payload. Our a/c do not sense their own weight, the Load weight is calculated from the load sheet, the BOW and fuel on board.
“Racing's important to men who do it well. When you're racing, it's life. Anything that happens before or after is just waiting.” ― Steve McQueen (Le Mans) 1971
 
Flow2706
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Re: Overloading Airliners - easily possible?

Mon Mar 08, 2021 3:43 pm

The calculations are done using standard weights for passengers, which can vary between legislation and type of flight. Many modern transport category aircraft can actually measure their own weight once in flight. This is usually done by a computer based on aerodynamic data (Angle of Attack). On the A320 a message comes up on the MCDU if the difference between the calculated and entered weight exceed 7 tons ("Check Weight"). Unfortunately it's easy to miss as it is not an ECAM warning and has no aural warning. If this warning comes up the pilots should verify the load sheet and compare it with the entered data. If everything is correct it can be an indication the the AOA sensor could be faulty. There was an accident during a test flight, XL888T, which was caused by frozen AOA sensors (and the pilots doing slow speed tests in an unstructured way and at a very low altitude). During this flight this "Check Weight" message was displayed to the crew and could have alerted them to the issue, but unfortunately they missed it and continued with the slow speed tests.
Personally, I experienced the "Check Weight" message a couple of times on the same aircraft (on approximately 20-30% of the flights). I suspected that the aircraft had an issue with the AOA sensors, but maintenance could not find an issue.
The most common error with weight and balance on large aircraft are data entry errors. If the takeoff performance calculation is performed based on the wrong weight it can have severe consequenses, tail strikes, runway excursions etc etc. To avoid these errors a thorough cross check of the inserted data has to be performed by the other pilot.
 
RetiredWeasel
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Re: Overloading Airliners - easily possible?

Mon Mar 08, 2021 3:45 pm

During the 90's, load control made a couple of 30,000+ lb load errors on 747-200F flights that I heard about. It' was noticed when the fuel burn on an 8 hour flight is significantly greater than the flight planned fuel used and in one case caused the freighter to land at Chitose AB, Japan. I'm sure with modern tech that those kind of errors are rare.
 
VMCA787
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Re: Overloading Airliners - easily possible?

Mon Mar 08, 2021 6:20 pm

RetiredWeasel wrote:
During the 90's, load control made a couple of 30,000+ lb load errors on 747-200F flights that I heard about. It' was noticed when the fuel burn on an 8 hour flight is significantly greater than the flight planned fuel used and in one case caused the freighter to land at Chitose AB, Japan. I'm sure with modern tech that those kind of errors are rare.


We had one going FRA-JED on a Red-Tailed F!. Couldn't figure out why we couldn't get above 270 on the way down. So we worked the perf numbers backwards and we a good 50,000 Lbs over gross at takeoff. Our fuel burn was a good deal more than planned!!!
 
r6russian
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Re: Overloading Airliners - easily possible?

Mon Mar 08, 2021 7:06 pm

I'd imagine in the US, take a short flight (like a domestic widebody for example) thats full to the gills of passengers and cargo, and combined with the required fuel ends up at or close to MTOW, it would actually be over, seeing as almost 70% of american population is overweight or obese. I would imagine that W&B calculations have some overhead built in just for this purpose, because theres not an iceberg chance in hell any airline in america could start weighing pax for W&B purposes. Imagine that media buzz and lawsuits.
 
johns624
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Re: Overloading Airliners - easily possible?

Mon Mar 08, 2021 7:45 pm

r6russian wrote:
seeing as almost 70% of american population is overweight or obese.
It's not just Americans anymore.
 
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Starlionblue
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Re: Overloading Airliners - easily possible?

Tue Mar 09, 2021 12:30 am

I'll add to the above that unless you have an engine failure between V1 and acceleration speed, overloading an airliner is unlikely to cause a problem beyond increased fuel burn. Unless your CG is also seriously out of limits, that is.

That being said, engine failures do happen, so we'd rather stay under MTOW. :D
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
VSMUT
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Re: Overloading Airliners - easily possible?

Wed Mar 10, 2021 10:20 am

TheSonntag wrote:
In General Aviation, it is quite easily possible to fly an overloaded airplane. Especially in typical trainers like the C172, if you put 4 people in it and fill up the fuel, the plane is very soon above the maximum take off weight of 1158 KG.


The C172 and PA28 are really 3-person aircraft with 4 seats. It was one of the first things I was taught when I began flying.


TheSonntag wrote:
How is this with airliners? Obviously, IT equipment and dedicated personnel help, but do the airplanes actually measure their own weight? Is it possible to overload modern airliners without anyone noticing, or would this trigger warnings?


It is based on trust and competence. It definitely happens, and more often than you'd want to know. Mostly just because the standard weights are a bit too small and the aircraft dispatch at MTOM. The aircraft can handle a little bit extra, there is some margin for mistake.

Then there are those who deliberately try to overload the aircraft. Everyone from Russians who have gotten the takeoff performance of their Il-76 down to an art so they can stash illegal contraband, to overambitious agents from the large freight integrators who "just want 500 kg more on the plane, all the other crews do that!". Luckily the latter is rare.
 
GalaxyFlyer
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Re: Overloading Airliners - easily possible?

Wed Mar 10, 2021 8:44 pm

Years ago, I remember seeing the B727 MTOW based on the number of lap infants on board and anticipated temp on take-off. Allowable weight wouldn’t be legal if the lap infants were actual accounted by the standard child weights. And, the temp at the push was a degree two over the max allowed, but it’d be right at take-off after taxiiing out in the setting sun. Pretty amazing in 1985.
 
Okcflyer
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Re: Overloading Airliners - easily possible?

Wed Mar 10, 2021 8:57 pm

I’m curious about the real time performance comparison the newer models are doing. How big of a performance deviation before it alarms? Do modern predictive maintenance systems use this info at all? Most if not all predictive monitoring is around non-structural parts. But it would be interesting if one could extend major checks based on real performance assessments over the life of the aircraft.
 
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Starlionblue
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Re: Overloading Airliners - easily possible?

Thu Mar 11, 2021 1:16 am

Okcflyer wrote:
I’m curious about the real time performance comparison the newer models are doing. How big of a performance deviation before it alarms? Do modern predictive maintenance systems use this info at all? Most if not all predictive monitoring is around non-structural parts. But it would be interesting if one could extend major checks based on real performance assessments over the life of the aircraft.


This already happens. More and more parts are replaced depending on wear, not depending on time.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
TheSonntag
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Re: Overloading Airliners - easily possible?

Thu Mar 11, 2021 1:36 pm

VSMUT wrote:
TheSonntag wrote:
In General Aviation, it is quite easily possible to fly an overloaded airplane. Especially in typical trainers like the C172, if you put 4 people in it and fill up the fuel, the plane is very soon above the maximum take off weight of 1158 KG.


The C172 and PA28 are really 3-person aircraft with 4 seats. It was one of the first things I was taught when I began flying.


Very true - in one training flight we flew with 4 people and while outside temperature was low, it was really an eye opener. I would not want to do that in 30 degrees C.

I also some times flew with my FI and another student pilot and when they let me fly a pattern solo, our nice 180 HP C172SP went up like a Saturn V (ok, not really, but flying with 200kg less IS a difference).

IMHO it is a good traing to fly everything from minimum weight with just a few fuel reserves (legal, of course) to MTOW.

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