Incorrect weight calculation 737 3

[LittleInch]

This report has just surfaced

https://www.theguardian.com/world/2...miss-on-board-child-weight-birmingham-majorca

Basically the load sheet allocated a childs weight to everyone listed as "Miss" instead of an a adult weight for everyone with "Ms". Apparently caused by a revised IT program in an unnamed other country where miss is commonly used for children.

Now something the size of a 737 it may not have been a huge issue, but I'm sure I recall a smaller commuter plane of 20-25 people which stalled on take off and when they recalculated all the Actual weights of the passengers the plane was over weight. US airways flight 5481 -

https://en.wikipedia.org/wiki/Air_Midwest_Flight_5481

https://admiralcloudberg.medium.com...crash-of-air-midwest-flight-5481-caa032313df6

Other things contributed more to that crash, but overweight without realising it was a major contributory cause.

So maybe not an engineering disaster, but a near miss and is a reminder than generic assumptions still need to be checked against your specific design or operation.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

Sounds like a big miss-stake!

 

[cranky108]

Why don't they weigh the passengers, and carry on's?
Need to balance wing, forward, and behind for the plane distribution anyway.

 

[1503-44]

If you see them weighing everyone, do not board the plane! They are trying to avoid taking on any little bit of fuel they can. The plane is sure to be maxed out.

They used to do that in Bogota. They couldn't lift a plane fully loaded with both passengers and fuel due to the high altitude (9,000ft) on a warm afternoon. They would fly to Panama City at sea level and top off the tank there, then continue on to Miami or NYC.

I've seen the same boarding offshore helicopters in Houston's hot humid air. Weighing 16 passengers. On "takeoff", the helicopter barely gets off the landing pad, still riding on the ground effect air cushion, on top of a parking garage and they just clear the guardrails, after two tries, once off the edge of the structure ground cushion is lost, but a quick nose down to gain airspeed before catching a telephone pole, then ... up, and hopefully, they're off to the rigs.

 

[RedSnake]

Weighing passengers would probably not go well with personal integrity. ;-)
Especially with the Misses.

Best Regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[1503-44]

On my first solo, turning left to leave the pattern without holding the usual rudder to compensate for takeoff power torque and for my 270lb flight instructor, I almost rolled over completely.

 

[LittleInch]

bimr - I already called that crash out. The plane didn't respond because they had incorrectly loosened the control cables and they didn't have enough nose down elevator pitch available.

My only experience of this was on a 50 odd seater turbo prop - can't remember which one, but it was a Friday night full plane. The fuel boys apparently over filled the tanks and the pilot came on and said they were going to try and burn some fuel off sitting on the runway, but then were told to shut down as they were making too much noise, so asked for volunteers to go the next morning. Eventually six people (!) got off. That was one hairy take off for me....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[djs]

It is my understanding that a fairly accurate weight of a loaded commercial plane can be found by measuring the landing gear strut length. I remember a pilot telling he always did that because the ground crew always under estimated the total load.

 

[JohnRBaker]

I suspect that one flight I was on was definitely overweight for the conditions. This was when Ozark was still flying, back when I was working for McDonnell Douglas. Me and my boss were on our way to St. Louis was some manager's meeting and we had to change planes in Denver. Now this was one of those old Ozark DC-9's. The flight was full, it was over a 100˚ outside and Denver is a mile high. I swear the pilot never actually took-off, he just got to the end of the runway and raised the landing gear. Fortunately, we were heading East so the ground was falling away from us and I think we just cruised until we had enough speed to finally gain altitude and burn off excess fuel. No body ever said anything, but I couldn't help but feel that that was the fastest that I had ever traveled while still having wheels on the ground.

John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Alistair_Heaton]

I have never understood why they have never put load sensors on the gear to tell you the true weight.

We have brake temp, tyre temp, tyre pressure,

Would have thought a strain guage bridge on the struts would give you something usable.

The standard weights are a bit suspect these days. I am meant to weigh 85kg including flight bag... I haven't been that light since I was 15 years old playing as a prop for the under 16's rugby team.

Oh we can work it out in the air with the performance parameters. You don't really have a problem until you have an engine failure. 1.2 tons though is a fair amount to be out for a 737 maybe 2 knts change in the V speeds.

 

[Alistair_Heaton]

Here is the report

https://www.gov.uk/aaib-reports/aaib-investigation-to-boeing-737-8k5-g-tawg-21-july-2020

 

[1503-44]

It does seem like some load sensors would not be such an impossible feat.

If you can work out tyre contact surface area x pressure = tyre load x no tires = strut load.
Do mfgrs have a chart of contact area vs pressure?

 

[Alistair_Heaton]

Not that they give to us.

They might have something in the maint manuals.

 

[EdStainless]

They can tell total weight from the landing gear hydraulics on most planes.
JRB, same deal taking off from 4 Corners (Farmington NM) in the afternoon, 5500' and 110F doesn't offer much lift. Good thing it is on a tall mesa.
One of the European carriers used to weigh people in groups.
What I always found funny is that they weigh my checked bags but not my carry on. I came back from Asia one time with a pair of 80# carry on bags.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[waross]

Flying in a King air in central America.
The plane was sitting on the tail support with the nose wheel in the air.
The pilot and copilot crawled up the aisle and as they were were strapping themselves in, the nose wheel came down and gently bounced twice on the ground.
At this point two passengers got off.
The 45 minute flight was made at quite a high angle of attack.
I flew in King Airs quite a bit in those days and the AoA on that trip was a lot higher than usual.
I kept thinking;
"If the engines quit, we are going to slide into the ocean backwards down this slope."

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[JohnRBaker]

What I always liked was flying in places like Indonesia, where after all the passengers were on board, they would come in and strap boxes of 'freight' into the empty seats and sometimes even place loose bags of stuff on the floor of an unused aisle. I'm not saying that we were ever overweight, but it just felt odd when for years you've been told to stow all your carry-on gear before they'd even close the door and pull-away from the gate.

John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Tomfh]

How come planes don’t have gauges built into the gear, as a cross check? Relying on calculations seems a rather error prone way to measure weight.

 

[waross]

I know the feeling, John.
On a small plane there was a space behind the right rear seats where the washroom wasn't.
They piled freight there.
One trip the freight was piled loose, almost to the ceiling.
On the top of the pile was a crate with an 80 HP outboard motor.
On landing myself and the passenger next to me were holding the outboard motor in place to avoid being crushed by it.
Flying down there was always an adventure.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Eufalconimorph]

How come planes don’t have gauges built into the gear, as a cross check? Relying on calculations seems a rather error prone way to measure weight.

"Regulations are written in blood" goes both ways. Not enough blood has been spilled due to this sort of issue for that to be required by regulation.

 

[Spartan5]

Weighing passengers would probably not go well with personal integrity

I’d wish they weigh me. They’re already treating me like freight anyway.

Maybe then I could get a discount that would offset the injustice that comes with being slotted between two 300lb mamajamas who can’t help but ooze into the highly priced real estate that I’ve paid dearly for.