Weight & Balance enhancements?

[targaman]

For the past 85 plus years the industry has been well served by the manifest weight & balance system (MWBS) or load sheet.

We as practioners of this fine art, pilots, dispatchers loadies etc are well aware of the garbage rule "Garbage in Garbage out."

However what we are not so well aware of is the sheer volume of loading errors that the load sheet system cannot detect.

On board weight & balance systems (OBWBS) using landing gear load sensors or axle strain gauges and associated software have been around since the early 1980s.

They have their detractors. A common cry is too innacurate in windy conditions and too many spurious warnings just before take off.

Few operators appear to trust the system and this borne out by the fact that the majority of systems pilots will come across on the line are fitted to leased or pool aircraft.

OBWBS are not a requirement therefore they will not gain general acceptance until they are. Is this a fair statement?

Your comments please.

[Genghis the Engineer]

The difficulties with on-board W&CG systems are straightforward enough, although perhaps not quite so simple to solve - a quick back-of-envelope sum suggests that you might get around ±5% weight error due to surface wind, and perhaps ±2% in CG position. That is an error too gross to be acceptable.

So, to cope with that you'd need a stack of wind tunnel data for the aircraft in ground effect showing effects of winds from various vectors, PLUS some kind of accurate windspeed instrumentation, PLUS you'd have to have the aircraft sat well clear of any rotor over buildings or other factors that would make the airflow over the parked aircraft unpredictable. This would basically mean taxiing it to the hold before you knew if you were accurately in W&CG limits! (And at some fields, that wouldn't be reliable either).


On the other hand, you can simply try and maintain a reasonable control and monitor over the loading of an aircraft. This aint complicated, it just requires to you weigh everything that goes on board and do some maths that my stepson, who failed his maths GCSE, could just about cope with - and in any case can be easily computerised.

Sorry, my money's on loadsheets.

G

[targaman]

I don't know where you get 5% windage error from? Manufacturers have a stack of wind tunnel data. That is how they designed a portotype and had it certified. You can also fall back on the Lift formula and good old Sine curve.

I agree the wind assesment is best carried out by an anemometer dedicated to that purpose. As for CG error that is not a factor as whatever weight is sensed on the strain gages is totalised. If the GG is in error the OBWBS detects that as a null position and in fact shows one the true location of CG.

I agree everythig that goes on can be weighed and then the load sheet assumes it's rightful place in the scheme of things. BUT the industry allows such things as standard passenger weights, standard carry on weights.......AND

we live in a real world where load is to put on the load sheet and left behind. load is put on the wrong aircraft, load is l........need I go on.

What I have been working on for some time now is I believe an answer to all the load sheet and OBWBS problems. An external weight & balance system

[747FOCAL]

Over the years many have tried their hand at designing an onboard weight and balance system. All have failed in deriving a system that could be certified for operations. Even if you could prove 10 to the negative 9th that a failure of the system would not cause a crash you are still stuck with designing a system that even one failure is unacceptable.

Boeing offers a weight and balance system on the 747-400. They also offer a dual backup system. The single system is standard on the freighter with the backups system being an option.

To date, only one 744 operator has bought the backup system as an option. I know from speaking with them that neither of the systems will ever replace the loadmaster.

Most PAX 744 operators that chose to pay for the WBS from Boeing have deactivated the system. Anything sensative will be knocked out of calibration by hard landings and dirt will end up covering any type of lazer or infrared calibration system.

It would be nice if you can get a system to work, but I think you will find it would be cheaper and easier to build a massive in ground scale that weighed the aircraft like they do at truck stops.

[targaman]

Entirley feasible I am assured. In Australia there exist 400 tonne weighbridges to weigh giant mining trucks.

It is only a question of getting our heads around the concept of weighing and checking the bal;ance of the whole plane in one pass over the inground eighbridge just before take off and just after landing.

Why after landing? To weigh intruders form outside the country that has the new system.

Simple, like all great ideas. As my instructor used to say. Keep it simple stupid and I can undrstand it.

[Genghis the Engineer]

There is a hangar at Boscombe Down called the "Weigbridge Hangar" (original name!) which could happily do a weight and balance on pretty much any aircraft size and shape - and an incredibly useful facility it was too.

Whilst I was there, I saw it used for aircraft from C130 to motorgliders, didn't particularly struggle with any, although I was never indoctrinated in the intricacies of it's use. It was I believe first used for the Bristol Brabazon.

G

[targaman]

Thanks for that bit of info. Weighbridge technology has come a long way since the Bristop Brabazon!

But the idea still is simple and effective.

Pity we don't have them in the taxiways at every airport.

Here is a another question for discussion.

How do regulators check an operators weight & balance system accuracy?

[targaman]

More discussion.

How many people know of large loading errors such as wrong load on board not manifested, wrong aircraft loaded, wrong loaded position, load left behind but manifested on board. More?

Any loadies, pole pushers or switch flickers got any more examples? Come on don't be shy. we are all anymouse here.

[Skut]

I've spent the last 2 years in load control and have seen the following errors:

- wrong aircraft registration (so wrong dry operating weight/index)
- wrong pallet weight
- wrong pallet(s) brought out to aircraft
- pallets loaded in wrong position

This is all down to human error and can be detected by simply checking your work (and others) thoroughly. I've seen some crews just take the loadsheet, sign it and hand it back. The dispatcher that used the wrong registration was suspended, I don't know what happened to the captain who signed the loadsheet (the registration is right in front of you on the instrument panel). I guess the dispatcher is there to check that eveything is correct but we all have our part to play. This doesn't include the pressure to deliberately misload by company reps who want to get all there cargo away...

Airbus have a crosscheck on C of G position, the loadsheet figure must be within a certain limit of the indicated figure on the cockpit screen.

[Genghis the Engineer]

Also seen a few times errors in initial W&CG, usually because of:-

- Confusion of aft versus fwd of datum
- Occasional mix up of units.
- Occasional mix up because of two similar types using different CG datums or slightly different moment arms for standard items.
- Hate to say it, but people who just do the sums wrong, use wrong moment arms, etc. I spent a happy half day a while ago sorting out a monstrous mess made by a well known "plane weighing" limited company of the W&CG for somebody's warbird that I was consulting on. They simply applied no common sense to the CG envelope, tried to shoehorn a 2-seat tandem taildragger into a standard form designed around godnosewhat and ended up with something totally unuseable.

As skut says, this is all down to human error, lack of training and competence, and lack of proper documentation control - nothing more complex than that.


I don't know where you get 5% windage error from? Manufacturers have a stack of wind tunnel data. That is how they designed a portotype and had it certified. You can also fall back on the Lift formula and good old Sine curve.
Negative. Aerodynamics is not that simple, and wind tunnel data used for design rarely take into account either ground effect or (probably impossible to) local airflow variations within the aircraft span (such as rotor over a nearby hangar). My 5% was a back of envelope sum by me only, but I think fairly realistic.

Dr.G

[targaman]

When I went to school (Pilot school) a long time ago.............

If as I do one remebers the lift formula, and who doesn't, then one knows that if all the variable are constant except, say TAS (Wind in the static case) and one knows that at lift off L=W then a prety accurate graph can be constructed from that point back to zero.

Since the aerodynamic force depends on the square of the velocity, doubling the velocity will quadruple the lift.

In the light aircraft case if the lift off speed was say 60 knots then:

1. There would have to be a head wind limit on weighing that aircraft of 60 knots. In practice probably more like 40 Knots operationally to allow for x/wind taxying.
2. If the head wind was say 15 knots the lift produced would be 33.3% of that required at lift off.
3. If the weight in still air is known by accurate measurement then a correction factor in this case of -33.3% would produce an accurate model weight.

Prototype trials in still air and in various wind conditions , over a 6-12 month time frame would generate an accurate and reliable weight correction model.

Ipso facto, no need for wind tunnel test data or even a copy of the test pilots notes.

[Genghis the Engineer]

The aircraft is normally weighed on the ground flaps up, gear down (the latter is pretty much essential!). Last I looked the flaps and slats were not retracted for take-off, so the function of safe windspeed to take-off or stall speed is far from clear.

The shape of the aircraft, any aircraft, will be such that the wind vector (as well as the scalar) will affect Cl and Cd on the ground (since the drag effects will act about a CG will above the undercarriage, that skew things as well). I'm afraid that you are probably being badly misled by the grossly simplistic explanations of aerodynamics used when training pilots.

You are never going to routinely find a spot, on any major airport that I've visited, where you can guarantee no significant 3D wind effects - in particular rotor over buildings, vehicles, trees, that hill over there.... This will all throw the results.


So, basically the enormous degree of uncertainty over both the actual 3d wind model around an aircraft on the ground, and the effects of that airflow pattern - which is infinitely variable - will have on the complex 3D shape of any aircraft - and then the resultant forces on the aircraft make accurate weighing of an aircraft outdoors, at an airport, a virtual impossibility.

Weigh the aeroplane by all means, but the only way you'll do it reliably is in a hangar or that great rarity, perfectly still conditions.



I'm afraid 'though, I remain of the opinion that the big issue is documentation control.

G

[targaman]

Great discussion.

How many engineers did it take to design a horse? I don't know but the result was a camel!

The beauty of computer modeling, is that we can improve the model with every new ongoing data experience.

We use the results of computer modeling everytime we pick up our CFP (Upper wind models).

I can remeber when a 14 hour flight could be +- 10 mins. I have flown many flights that are +- 2 mins or less after 14 hours.

The added beauty of trialing a prototype is that one can correct computer models with hard data.

The argument that one needs to find a completely still air position on the airfield, as in a hangar is akin to the argument that one needs to find a completely perfect MWBS (Load control, loading and load data sheet system).

If we take the analogy of speed monitoring and compliance on the road we can say the current system is like te police being issued with a note pad, pencil and stop watch.

Their task? Time a vehicle between two staitonary objects (Lamp posts) and bingo you have the third element, speed.

Some police officers will be very very good. Some mediocre and some lousy. Of course the legal defence team would have a field day and there would likely be no convictions.

Give the police however an external, accurate independent and verifable tool (Radar or laser gun) and bingo you have convictions.

So enough of the hair splitting. Even with a perfect, load control system, perfect loading procedures and personel and a perfect load sheet, how is the the weight & balance checked by external, accurate, independent and verfiable means?

Why does it have to be checked this way? Because any system design that has any measure of validity needs to be independently checked and verified.

Maybe a better way to look at the issue is to study the present system from systemic and analytical angles. I have done that and I have come up with a threat & error management model that I am willing to share for discussion and improvement, privately.

[Genghis the Engineer]

How many engineers did it take to design a horse? I don't know but the result was a camel!
Wasn't this Engineer.


The beauty of computer modeling, is that we can improve the model with every new ongoing data experience.
For flight safety related data, not on my watch. FS related software is tested to death, then frozen with nobody having the right to change it without a thorough review. (And yes, I have written computer loadsheet systems.)

The argument that one needs to find a completely still air position on the airfield, as in a hangar is akin to the argument that one needs to find a completely perfect MWBS (Load control, loading and load data sheet system).
I've never seen a bad one so long as people were properly trained and stuck to the rulebook.

If we take the analogy of speed monitoring and compliance on the road we can say the current system is like te police being issued with a note pad, pencil and stop watch.

Their task? Time a vehicle between two staitonary objects (Lamp posts) and bingo you have the third element, speed.

Some police officers will be very very good. Some mediocre and some lousy. Of course the legal defence team would have a field day and there would likely be no convictions.

Give the police however an external, accurate independent and verifable tool (Radar or laser gun) and bingo you have convictions
Not when it's me, I've succesfully shot down a police conviction on "data quality" issues. The police force in question didn't know their arse from their elbow when asked to justify their evidence. Too many people are unduly impressed when a computer or electronic measuring is involved.

It's similar to the posh EFIS systems we're seeing on light aircraft now - they still run off the same 50c sensor that the old steam gauges did. Yet because it's electronic people trust it. Hah!

So enough of the hair splitting. Even with a perfect, load control system, perfect loading procedures and personel and a perfect load sheet, how is the the weight & balance checked by external, accurate, independent and verfiable means?
That's why the quality system behind the production of load sheets is so important, and the captain is *supposed* to check and sign the loadsheet - he/she is the second check.

Maybe a better way to look at the issue is to study the present system from systemic and analytical angles. I have done that and I have come up with a threat & error management model that I am willing to share for discussion and improvement, privately.
What are the main data inputs, and what equations do you use for data combination? - for the latter I generally (for similar problems) use combined sum of squares of partial derivatives (of the whole function) multiplied by the numeric values of derivative variables. Maths is a bit messy, but the results are very reliable - by which I mean safely conservative, but not excessively so.

Don't bother with any sales pitch, I just fancy looking at some nice juicy data analysis - that's what's at the root of what you're talking about.

G

[targaman]

Main data inputs are:

Recorded a/c weight
Speed over platform correction. (0-5 Knts)
Head wind speed.
Gust factor.
Model wind correction.
Aircraft registraton capture.
Aircraft performance data (Limitations)
Aircraft CL data from manufacturer (If available)

The mathematics are for the software engineer and are proprietary.

As for the advertising comment.

Part of the problem of introducing an external weight & balance system to aviation is the perception (False) that the present system is "safe."

Until it is recognised that the problem of loading errors is real and constituets a "significant" threat to safety the argument can get mired in defensive rhetoric.

One of the false arguments currently in vogue amongst many regulators is that the problem is restricted to light RPT aircraft.

The logic for this is the simplistic analytical view shown as follows.

A comparison of various aircraft types indicates that the ratio of passenger weight to overall aircraft weight is inversely proportional to the size of the aircraft. For example, in a Boeing 747, the passenger weight represents approximately 9 per cent of the aircraft's weight (450 passengers at 188 pounds, aircraft of 875 000 pounds) whereas the passenger weight in a Cessna Caravan can represent approximately 22 per cent (10 passengers at 188 pounds, aircraft of 8550 pounds). For aircraft under 12 500 pounds, there can be significant deviations from the published standard passenger weights due to the small sample size (nine passengers or fewer). This deviation error is further amplified in small aircraft due to the higher percentage of total aircraft weight that the passengers represent. If a small aircraft is being loaded to maximum gross weight, this discrepancy in passenger weight could result in an overweight condition that adversely affects the safety of flight. For example, stall speeds increase with increased aircraft weight; if the pilot is unaware of this change to aircraft performance, the reference speeds used for critical phases of flight will be incorrect.

The real world however is not this simplistic.

In my threat and error model I have considered a range of systemic threats as well as a a wide range of analytical threats.

When an error occurs it is the eroor management or mismangement that determines the risk.

The main problem as acknowledged by leaders in the accident investigation field is that large RPT aircraft do not have any other weight and balance evidence than the load sheet and expert witness testimony after the crash.

Reconstruction, the convential method for accident investigation is often impossible or impractical with large RPT aircraft.

I don't want to get banned from this forum for giving out a commercial web site but if you are interested in the threat & error model development please email me.

Once more in the industry are aware of the real problem and the need for a solution (Hard data, education and publicity) then the discussion should be how do we implement change.

Chok dee.

[john_tullamarine]

A couple of considerations ..

(a) do we see any hard evidence that a weighbridge system operating in real world conditions demonstrates statistically more reliable data than a well-controlled airline-style system ? Presumptions and good intentions are fine, but folk like Genghis and I, being anal engineers, are more likely to be swayed by numbers we can play with ...

(b) the comment re numbers of folk is valid for small aircraft except that the concern is population mass distributions rather than a ratio of passenger to aircraft weight. I suggest that the latter is a red herring argument.

However, there is a straight forward statistical approach to this problem, as has been done in Australia some years ago by CASA's John Klingberg. That study is not hard to get for reference.

Once we get to large aircraft, provided that the standard weight data is representative of the population on the aircraft (or vice versa, I guess) the standard weights work out fine.

I can remember numerous times having to weigh passengers .. only to find that the standard weight calc was so close to the scale result that we really had wasted our time ....

[targaman]

I am not surprised the discussion has fizzed. Pilots don't get to see what goes on behind the scenes. Neither for that matter do most flight/cabin crew.

Some time spent chatting or preferably watching a load master and a load controller in action followed by some time watching the loaders in action might change that.

In the meantime start building your own data base of over weight operations. That is not necessarily over maximum weight per se but over load sheet weight. You can do this quite easily on FMC equipped aircraft.

Check the flight progress preferably on time. If early or late make a correction. If on time and at altitude on track but down on fuel. (CFP total) and below fuel burn (CFP).

You can check the drag by simply checking the flight control indicators are in the flight position and not causing unexpected drag.

Check the actual fuel flow in flight required to maintain CFP (Company SOP cruise). (Econ/LRC etc).

Check the thrust required for a given CFP (FMC) weight in flight and compare to actual power being applied to maintain Cruise. This will confirm you are heavy. But how much heavier?

Alter the weight in the FMC down a few hundred/thousand poinds at a time until the CFP fuel flow is achieved. Then note the difference.

That iis an indication of how much heavier you are right now. You will have to exptrapolate back to take off to get a take off weight.

Trim? Bad luck old chap, the load sheet is always correct!

[john_tullamarine]

Actually, the trim sheet is rarely "correct" as it is entirely routine for the designer to build in "design errors" to account for "usage errors" .. with an expectation that the two cancel out on most occasions so that, regardless of what the sheet might say, the aircraft loading has a high probability of being within the TC limits.

There is a basic presumption in the use of typical manual loading systems that there are checks and balances to guard against gross finger trouble errors .. certainly doesn't guarantee the absence of error but, if sensible and used, the overall quality of the manual system ought to be reasonably good.

Some examples of checks and balances are ...

(a) having a crew member check the can weights and order of loading AFTER the load is on board (or as the cans go in the door if a post loading check is not feasible) to make sure that the load at least matches the trim sheet. From a number of years on freighters, I have to say I didn't see gross errors often, but certainly saw them occasionally. Reload only means a delayed departure.

(b) having the certifying crew member (normally the captain) double check the numeric additions while a second crew member double checks the trim calculations using a load adjuster (slide rule style IU calculator). Takes negligible time and I have seen it save the day once or twice. This can be used for freighters or pax operations and is a sound philosophy if the load sheet is presented as a computer printout .. this latter, very common, technique is not usually checking friendly for the crew.

(c) on-board oleo check systems. These are rarely particularly accurate but those of which I have had experience generally have been consistent so a deviation in expected delta (error, if you like) is the alert signal.

.. and I certainly agree that some pilots, not seeing what goes on behind the scenes, can be guilty of apathy. Most, however, on larger aircraft (at least in my limited experience) have been attentive to the reasonable double checks which can be made ..

Are you able to make a case for real world accuracy and repeatability using a weigh bridge check system ? Specifically, one needs to address, satisfactorily, those sorts of error sources which Genghis, among others, has suggested as being worthy of concern ...

[Blacksheep]

I think you'll find that on-board weight and balance gauges go back way before the eighties. They were certainly fitted in BA's 707 freighters back in the seventies when my hair was still brown. They were never particularly accurate, but were good enough for checking the honesty of those who declared the weight of the cargo items. There are plenty of unscrupulous cargo agents in this world, who don't give a damn about the load sheet as long as they get their back-hander from the shipper. Without an on-board system, how do you double check?

Now, you can argue that the declared weights on the load sheets are correct as much as you like, but the worst I've seen was an Argosy that flew into our airport with a loadsheet that showed that the cargo weight was within the aircraft capacity. The captain insisted on having it all weighed in front of him during the unloading process, when it was found that the actual weight was almost double the declared weight shown on the loadsheet.
As it was, at the departure end this aircraft had barely made it off the end of the runway and luckily had a nice obstacle clear harbour to gain a bit of height. Being now fully aware that he was grossly overweight, the skipper elected to continue and burn off all the fuel, rather than take the risk of landing as he was.

An on-board system would certainly have picked up such a massive load sheet error.

[targaman]

Are you able to make a case for real world accuracy and repeatability using a weigh bridge check system ? Specifically, one needs to address, satisfactorily, those sorts of error sources which Genghis, among others, has suggested as being worthy of concern ...

Yes I believe a system such as my patent pending weigh bridge (Name witheld for forum rules reasons) can reliably, accurately and importantly, verifiably, check and warn crews of loading errors both small and large.

How can I substantiate my claim? In a number of ways..

1. There is plenty of experience in the weighing industy to base accuracy assumptions on. Still air as a start point. There is no great mystery, as some would like to believe, surrounding weighing objects both large and small. Remeber that the load sheet is comprised of individually weighed items. Are you questioning the accuracy of the load sheet from a weighing standpoint?
2. Model construction with corrections as discussed earlier is really only a marketing tool. That said it will form the basis of the protype computer model.
3. The real world experience happens when the prototype is trialed over an extended period, using real aircraft on real days (Yes windy, icy, raining, foggy, dusty, snowy and in typhoon conditions).

Dare I say it here? The aeroplane you fly today started life as a prtotype that was used to substantiate the designer's claims.

The problem in the industry is not one of technology, as any SAWE member realises but rather our defensiveness when faced with change. This is perfectly understandable if the target of the change is the present system and its fine practioners. But t is not! That point get's lost in the emotion of the argument.

The weigh bridge system is designed to COMPLIMENT and ENHANCE (Capitals added for emphasis) the present MWBS.

But additionally the present system lacks a final INDEPENDENT check and warning system.

I agree with Ghengis and others we as practioners do need to exercise more care and responsibility with respect to the accuracy of the data that makes up the load sheet result. But as we all know real worls pressures preclude many of the checks we would like to make before door closing.

My other concern in this regard is with the new generation of pilots who have cut their teeth on glass cockpit aircraft.They have been successfully immunised, as any video game expert eventually realises, from the real world outside the video screen

A healthy suspicion of all human data inputs, with a large dose of good luck, has given me a 41+ year (21,500+ hour) safe flying career.

Lastly I haven't heard anyone express the desire, nee need for, an alternative system to the present MWBS. Maybe it is thought of as a nice to have not need to have system? Maybe it is expected to cost a poltice?

The fact is that several aviation stakeholders currently use aircraft weight to make money right now.

Airports (Some) charge by MTOW for landing fees (A poor choice of term).

Some regulators allow placard weight changes (HKG for example) to save landing fees.

ATS are increasingly basing their airways fees on aircraft weight.

Regulators are aware of the growth in aircraft weight between D checks but have no practical way of confirming that.

I have developed a new paradigm for use by airports that uses yield management to make money from the existing fleets.

Yield management?

The concept that allows you to pay double for your ticket, hotel room or rental car than the guy sitting next to you on a plane.

It is interesting to note that computer models are being developed that can compute weight & balance on board a ship at sea. That research is reaching the point where it will soon be capable to provide real time weight & balance mesurement in most sea conditions. Seems a shame to be overtaken by the venerable senior service.

Chok Dee

[john_tullamarine]

(a) Argosy ? .. twice the payload ? .. given that the beast had trouble enough making any sort of first segment at average weights ... it is, indeed, impressive that it managed not to get its belly wet on the example occasion ...

(b) Of course there needs to be checks and balances to keep the dishonest only moderately so ... that goes without saying.

(c) I have no problem with a weighbridge's being accurate .. there is plenty of room to straingauge the supports .. only the external conditions and their effect on the calibration is of concern ... as a regular user of both platform and loadcell aircraft weighing systems, the calibration transfer to the real world of weighing is a constant problem ... one which many of my colleagues seem not to concern themselves with to any great extent ... particularly with loadcell systems one can generate errors galore by being cavalier with the conduct of a weighing.

(d) prototype testing makes good sense ... what sort of numeric results have you had to date with model and full size prototype units ?

(e) those of us who are engineers are not daunted by change .. but see not much point of change for change's sake .. if, however, the mousetrap is a better product .. then we are all for it .. provided the cost/benefit numbers make sense as well.

(f) as for the PacMan brigade thing .. that is a whole new ballgame of problems and belief construct worries ...

[Blacksheep]

Not twice the payload, John, just twice the declared cargo weight. Twice the payload would definitely have seen them out water ski-ing!

As to the Pac-man thing, there's much said about glass cockpits from those who don't really have a clue. The word "Luddite" springs to mind. Flying a glass cockpit aeroplane is a very, very long way from playing computer games. Even FS2004 - Century of Flight ;)

It wouldn't be too difficult to have an on-board weight & balance system that automatically checks for out of limit loading and provides a warning. Even prevents the engines being started, perhaps? :hmm:

[john_tullamarine]

If

(a) it works and the reliability is appropriate

(b) the cost/benefit is sound

I'm for it ...

As to the Argosy .. maybe I should read the tale more carefully .. haven't been in one of those for a LONG time.

Have you ever seen the booms do their thing from an in-trail position ? A wonder to behold.

The only aircraft I have come across where the first segment is more often than not the critical takeoff case ...

Re glass cockpits ... yes to all that .. but, in the absence of intelligent scepticism ... such toys can breed indifference and a total lack of back-of-a-fag-packet mental double checks .. ? A bit like pocket calculators .. while it goes well it's wonderful ... but, when it turns to custard, you are still back with the basics in the little boxes somewhere in the middle of the panel to get you home ...

[targaman]

"I've spent the last 2 years in load control and have seen the following errors:

- wrong aircraft registration (so wrong dry operating weight/index)
- wrong pallet weight
- wrong pallet(s) brought out to aircraft
- pallets loaded in wrong position"

"I have witnessed many a time when we took off grossly overweight for various
mistakes. I recall an incident where the airline I worked for took off 10
tons over the MTOW (a loader had forgotten to empty the belly holds!) and
the crew failed to spot it. On a 147.4t SMTOW, this is a fairly large
percentage !"

"Having witnessed also the eagerness of exporters to declare lower weights,
with agents willing to "accommodate", it does surprise me we have not had
more accidents related to weight problems."

"It is not only different countries, it can also be different carriers within the same country using different standards

It is the standards of the operator of the aircraft that are used for weight and balance purposes. So even if a passenger is through checked on from one flight to another, there could well be different standard weights used. The system counts number of passengers (often split into Male, Female, Child and Infant) and multiplies by the standard weights for the loadsheet"

These are some of the unsolicited comments I have received on the topic of aircraft loading errors.

I have one more. Asian (Unnamed) carrier agent loaded all the cargo on one side of B744 without crew checking actual loading. Made for interesting conversation after takeoff. The result of investigation? Boeing, when queried by company, said flight was within safe limits. What aileron trim to set for take off? No reply. SOP change? Check your cargo before take off. Stops nasty surprises!

More comments, feedback, experiences please?

Chok Dee

[targaman]

Why we don't weigh aircraft every time we take off.

Scene butchers shop (Remember them?).

Mrs Chaffcutter says. "I 'll have 5 kilo of lean rump plese." (Thats 11.23 Lbs )

Burcher Bill says. "Lets see. An average standard kilogram of rump is 900 grams, so........five kilos would be.........4,5 Kilos, right?"

"I guess." Says Mrs Chaffcutter. "But why dont you just use scales and weight the meat?"

You can't trust them scales Mrs C. The government doesn't, they give us average (Standard) weight tables to use instead."

"OIC" says the trusting Mrs Chaffcutter.

[Milt]

Wonder where the cg ended up in the following example.

Post lifted off the thread on "What ballast are you carrying around"

UNWANTED BALLAST

Back in my youth when I was just a boy pilot, we flew enormous quantities of freight into the New Guinea Highlands on DC3s, there was no other way, no roads, so everything went by air.

One particular DC3, known as being 'gutless', had, over the years carried literally thousands of tons of cement into the highlands. Slowly, oh so slowly, the cement dust was sifting down through the floor cracks and settling on the keel, and in the tropical humidity became hard.

At the next major overhaul, 2000 Lb of hardened cement was removed from the keel. After that, the aircraft performed just as well as any other.