United Overweight Takeoff on Computer Mistake Prompts Changes

[DOVES]

Heathrow Harry:
http://www.pprune.org/rumours-news/4...ml#post7358393

We had it on DC-8 in 1970's

[framer]

So either fit them to the gear and know how much you weigh, or at the least install some measuring pads at each runway hold point.

That would solve some problems but not all problems. The crew of the Emirates flight in Melbourne both understood that they were at 362 Tonnes, they just didn't know that they had done the data for 262 Tonnes.

[saltyfish]

Strain Guage/Load Cell

Boguing,
Second that thought.
This seems to me like it would be a perfectly workable solution.
By locating load cell/strain gauge arrangements near or at the MLGs and NG, the weight and CG location could be measured directly, thus eliminating guesswork.
It looks like STAN did just that.
The whole setup could be periodically checked/calibrated against ground pads.
The challenge would then be to come-up with a setup that would remain accurate and calibrated in spite of the higher loads encountered during landing and wide temperature variations.
Could someone more knowledgeable on the subject shed some light?

[hetfield]

Don't know what UA procedures are. Working for a major EU carrier we received the flightplan (weight/fuel calc) about 30-45 min before departure. This gives a pretty good idea about T/O performance. After pax checkin completed we received the loadsheet.

Most of the time only minor changes.

Anyhow, a gross mismatch like not taking in to account a complete pax section would have been noticed by the pilots, ehhrrrm most probably.

[MrMachfivepointfive]

If we can send a car to Mars surely we can come up with sensors on the undercarriage that tell us how much weight they are carrying?

The problem is the wind load on the aircraft sitting on the tarmac. In anything but still air, the weight measured at the oleos will be off.

[Joetom]

Or you could ask yourself: Does it make sense?


(Complacency will kill us all)

Yes, This could save some, but some some will slip through.

It just reminds me of that triangle thingy, keep using up all the lower blocks and then just the top remaining one to be picked up and used, horrible.

It just seems a shame with so much data available (weight/trim/C of G/pwr/flaps/location/avail runway/accel/weather/temp/pressure/position of controls in the flight deck/state of a/c systems etc etc) that we can't have a nice safe attention getter when it's reqd.

Investigation: AO-2012-020 - Pre-flight planning event - Boeing 737-476, VH-TJL, Melbourne Airport, 22 November 2011

Thinking of this one above and the EK at MEL, just great examples of how crew can get out of the real loop.

Infact, from memory the EK crew had operated at weights between 160-360Tones and flight times between 2-12 hours and a variety of runway lenghts avail, so I can understand when they did not question when the engines spooled up and all the pointers and indicators were at low values, again from memory, it may have been a full de-rate T/O !!!

[Basil]

The problem with a safety system is that you don't know how many accidents it has prevented. Without that proof it's easy to decide, like our 747 Classic weight and balance indicator, that it is not necessary and save on maintenance costs.
Having said that, would anyone argue for the removal of TCAS or GPWS?

What if Airbus fitted a sidestick position indicator which could be seen by both pilots - and a captain standing behind the seats? (or moved the poles to the front of each pilot)

[framer]

I think that adding alarms or weight strain gauges or installing weigh plates at holding points would have some benefit, but not as much as we would hope.
How about addressing the underlying factors that actually cause competent , experienced pilots to make errors they never thought they would make. Ie distraction during performance calculations, pressure to depart on time, added complexity to the preflight procedures with a new task jammed into the procedure every six months or so.
For example, if when the performance calculations were to be done, the flight deck door was closed and radios turned down, and the refueller / Engineer /gate staff / Purser / waited quietly in the front galley until it was opened.....do you think that would reduce the number of performance errors due distraction?
It would go a long way towards it. It would also impress upon the pilots the importance of the calculation so as to guard against complacency. The Captain of EK407 said he had drifted into complacency over the last year or so regarding distractions during this phase and on that flight there were a lot of distractions/ interactions occurring. There were other factors obviously like poorly designed SOP's.
Anyway, my two cents.

[boguing]

Slightly ashamed to admit that my cry for strain gauges on the aircraft or ground pad would not account for surface wind. Pretty sure that it would work when up and cosy with the terminal and in crosswinds elsewhere, but it is not an absolute solution.

[pontifex]

In the early days of the V Force we did have a system called ACP or accelleration check point. It was a specific, well marked point on the runway by which a pre calculated speed had to be attained. Otherwise, abort. Of course all take offs were from a very specific point with the brakes released just as engines were coming up to full power. Thus, this technique would not work with normal civil practise. When I became a civil pilot it always seemed slightly "gash" to me that such exact calculations were done but that the most fundamental element, the point of initiation of the roll, was so indeterminate in practise.

[Prober]

STAN

Fantastic to actually see one! It totalled the oleo weights and gave a c of g estimate. On the Merchantman (VC9 or converted Vickers Vanguard for those without a memory as long as mine), it was a very rough cross-check. There were no known limits which had to be observed and it was, in my view, mostly psychological. If it did not match, even roughly, your own T/O weight estimate and the load sheet weight, then you probably had a problem. The c of g was supposed (IIRC) to be roughly within 4% of calculated. That certainly saved my life on one occasion. But most importantly, what it do do, was make you have your own estimate of the T/O weight in mind.
Can you force someone out of complacency? Well, this went some of the way.

[DOVES]

Monitoring takeoff acceleration

Dear Sirs.
The CHECK "Time to 90 kts" could have been, and can be, of some help in so many occasions.
I found, among my many FOMs the SE 210 Performance Chart.
Entering: Temp., P.A., A/C Weight, Wind Comp., Rwy Slope, Eng. bleeds, Flaps position, Rwy contamination, it was possible to calculate the acceleration time (sec.) to 90 kts.

[error_401]

I used to fly on four variants at the same time PAX and CARGO. To have something to crosscheck loadsheets for plausibility because of the very different masses I had a sticker on my clipboard with:

DOM: Dry operating mass (based on a standard catering) of all variants
Wingspan:
Height:
Wheelbase:
Full turn radius:
(The span and other measurements are very helpful when doing a lot of charters.)

Up to today I've seen such very helpful stickers only in trucks.
Would greatly enhance awareness when DOM was e.g. found on the limitations placard instead of hidden in the performance section of the AFM or OM-B as we say over here.

I always crosscheck for plausibility using different figures from different sources:
DOM + FUEL + PAX (at 100 kg each including bag) = RAMP MASS

DOM (you should have that from your company or at least have an approximation)
FUEL (you should defintively know about that)
PAX (not what's on the loadsheet but what your purser tells you she/he has counted)
CARGO (the only source may be the loadsheet - but to some extent you even have to trust that)

Figure out your own requirements.

[DownIn3Green]

Yeah, well, as a Capt I know how. Much power is required to start my taxi based on what I think I weigh. If it's too much, time for a reweigh. Especially true in cargo ops. To miss by 20,000 lbs. is beyond the scope of my imagination. Maybe the Captain was one of those affirmative action hires from the 80's...Where's 411a when you need him, RIP...

[At ease]

No expensive measuring pads needed.

The heavier the aircraft, the closer to the ground it will be.

A laser light installed on the bottom of the fuselage at or near C. of G. should be able to give a reasonably accurate distance to the tarmac.

This type of laser, found quickly with the help of Mr Google, gives an accuracy to 2mm:

Laser Sensor Applications » Blog Archive » Drill Depth Measurement » Laser Sensor Applications

Obviously, an apparatus developed specifically for aircraft use would be even more accurate.

I imagine an a/c overloaded by 20,000lbs would compress it's main oleo's by more than 2mm.

It would not be hard to develop tables calculating the "ride height", if you will, for all weight conditions from empty to maximum allowable.

If the laser measurement distance on an overloaded a/c shows less than that allowed for an entered condition.......no pushback.

I thank the "Dambusters", and their downward triangulated spotlights for this idea.

[D.Lamination]

The A350 will have a takeoff acceleration monitoring system.

For me the analog basics say: All commercial airliners are designed for a similar cruise speed off similar runways and therefore have similar wing and high lift device designs.

I know from experience that a 350T aeroplane from any manufacturer going long haul will have a V2 between 170-180 kts. A computer that tells me V2 is 150-something is just wrong or at the very least worthy of serious investigation.

[sb_sfo]

You'd also need to factor in shock strut pressure if you use a laser.

[EEngr]

You'd also need to factor in shock strut pressure

Right. And don't forget the static friction in the strut seals.

[DaveReidUK]

You'd also need to factor in shock strut pressure if you use a l@ser.

Tyre pressure too, come to that. I suspect there are too many variables involved for it to be a feasible solution.

[At ease]

I believe the tyre pressure situation has already been looked after:

Aerospace | Wireless Sensing Solutions | Aircraft Tire Pressure

If the T/P measurement is within spec, then the crew needs to look at other reasons why the laser "ride height" indication is too low today.