Aircraft weight
They are only called Weight and Balance forms by common usage, but that is still wrong. As I said before, if you are entering values in pounds or kilos then you are entering values as masses, the unit of weight is the Netwton. You don't enter Newtons on your forms , do you?
If you go into a german market and buy a half-kilo of peaches, measured in a spring balance, then he is selling by weight regardless of whether the unit used is kilos, newtons or punts (500g).
PDR
*OK, you can do a dynamic parametric measurement using velocity when subjected to a certain force, but the only people who do anything close to that are the baggage hadlers at chicago when they throw your baggage down to the tarmac on unloading
PDR
In order for an inaccurate weight sensor to be of any use, the error component would have to be consistent in both magnitude and sense. I don't think you can reasonably assume that to be the case. If if isn't, then all you will get is a string of false "overloaded" alarms, which will do nothing for despatch reilability
I recall that quite a lot of work was done, once upon a time, investigating the possibility of weighing aircraft on the taxiway with equipment similar - in principle - to that used for vehicle weight checks.
The need for still air was one problem, maybe insuperable.
The idea was to have a check for gross error that could be followed up if necessary. ATC could advise the crew of their indicated weight. It might even be possible to measure the distribution of weight between the MLG and NLG, as another gross check against CoG limitations.
I have always thought it would be a good idea, used for that purpose. After all, it's usually the errors measured in tonnes that kill, not the smaller discrepancies.
EDIT: Out of interest, I just did a search and found this. It seems I'm well behind the curve, as usual.
The need for still air was one problem, maybe insuperable.
The idea was to have a check for gross error that could be followed up if necessary. ATC could advise the crew of their indicated weight. It might even be possible to measure the distribution of weight between the MLG and NLG, as another gross check against CoG limitations.
I have always thought it would be a good idea, used for that purpose. After all, it's usually the errors measured in tonnes that kill, not the smaller discrepancies.
EDIT: Out of interest, I just did a search and found this. It seems I'm well behind the curve, as usual.
EDIT: Out of interest, I just did a search and found this. It seems I'm well behind the curve, as usual.
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self-weighing
As to one potential error in self-weighing, frequently mentioned here, surely the surface wind is a non-problem. Presumably any aircraft that requires a significant rotation (almost any big airliner I would have thought – perhaps any tricycle aircraft) to lift off is generating little lift on the taxi-way. Indeed, this is the posture of the aircraft when it rolls on the runway, a posture designed to give minimum drag and therefore little or no lift.
Anyway, what lift an aircraft might get from any particular wind can be calculated by the aircraft manufacturer to subtract from the observed weight readings.
Actually an offset wind will generate different elements of lift as between each mainwheel set, giving the crew a clue to the value of the total readings. Perhaps in that case a good reading might be adduced by applying the reading of the out-of-wind mainwheel set to both sides.
In the Bogota prospectus the configuration includes a laser printer but no anemometer. Enough experience of that installation must have accrued to show whether surface wind has been any problem at all.
A quick look at Wikipedia tells us that most of the 747 hull losses over the last twenty years are freighters. At least two of the freighters were disastrously badly loaded. I suggest that the industry knows there is a risk of misloading, but that resulting losses have proved bearable so far. The cure we are discussing is expensive. I assume that the calculation for the airline companies is that freighter losses cost them little – perhaps no more than increased insurance premiums. Misloading of passenger aircraft is relatively difficult to get wrong. So while the litigation and reputational cost of a passenger aircraft loss is very great, airlines have little reason to fear misloading as a cause of such a loss.
So, how much do we care that our freight-dog friends are not being looked after properly by their employers ? (Don’t anybody mention Lithium-ion batteries – OK?)
Anyway, what lift an aircraft might get from any particular wind can be calculated by the aircraft manufacturer to subtract from the observed weight readings.
Actually an offset wind will generate different elements of lift as between each mainwheel set, giving the crew a clue to the value of the total readings. Perhaps in that case a good reading might be adduced by applying the reading of the out-of-wind mainwheel set to both sides.
In the Bogota prospectus the configuration includes a laser printer but no anemometer. Enough experience of that installation must have accrued to show whether surface wind has been any problem at all.
A quick look at Wikipedia tells us that most of the 747 hull losses over the last twenty years are freighters. At least two of the freighters were disastrously badly loaded. I suggest that the industry knows there is a risk of misloading, but that resulting losses have proved bearable so far. The cure we are discussing is expensive. I assume that the calculation for the airline companies is that freighter losses cost them little – perhaps no more than increased insurance premiums. Misloading of passenger aircraft is relatively difficult to get wrong. So while the litigation and reputational cost of a passenger aircraft loss is very great, airlines have little reason to fear misloading as a cause of such a loss.
So, how much do we care that our freight-dog friends are not being looked after properly by their employers ? (Don’t anybody mention Lithium-ion batteries – OK?)
Last edited by rlsbutler; 2nd Feb 2018 at 00:29. Reason: spelling
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We had sensors on the gear legs of the 747-200s in the sand box.
It was an option from Boeing, guaranteed to within +-2% if memory serves right.
We probably used it for secondary or back-up to the Load Sheet.
It was an option from Boeing, guaranteed to within +-2% if memory serves right.
We probably used it for secondary or back-up to the Load Sheet.
A quick look at Wikipedia tells us that most of the 747 hull losses over the last twenty years are freighters. At least two of the freighters were disastrously badly loaded.
As TowerDog notes, there are onboard load sensors available for the 747F (I know some 747-8Fs are so equipped, although I'm unsure if it's basic or an extra cost option).
Last edited by tdracer; 9th Feb 2018 at 06:47. Reason: fixed typo
I don't think any of the 15 or so 747 accident hull losses in the last 20 years that can be attributed to being badly loaded, but it's certainly true that two-thirds of them involved freighters.
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. there are onboard load sensors available for the 747F
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Mis-loaded B747 freighters
tdracer #29 and DaveReidUK #30.
I agree I have overstated the problem, after reading through the ASN Aviation Safety Database for the 747.
As it happens the two hull-losses that I had in mind are not straight-forward arguments for self-weighing: MK 1602 at Halifax 14 Oct 04 and Cargo B 3101 at Brussels 27 Oct 08. In both cases the physical loading was not in question; the data were mis-loaded by the flight crew. In those situations probably neither flight crew was enough on the ball to make prudent use of any cautionary information from the undercarriage.
Indeed, the Cargo B crew belatedly corrected their load figures, so an undercarriage cross check would only have comforted them; their disastrous mistake was not to recalculate the take-off speeds to fit the 100 tonnes extra weight they had stumbled upon.
As to the Bagram loss, I would insist that “improperly restrained cargo” is “badly loaded”, but that has nothing to do with self-weighing. Still, of the three cases, this was one where the captain could have felt “if they get that wrong, what else are they going to get wrong ?” To my mind the critical failure – and unbearably sad to tell – was that the aircraft loadmaster, on the ground at Bagram, seems to have seen that the restraints fitted at Camp Bastion were failing but could not bring himself to get them fixed before his aircraft again took off.
If I was to persist with my case, I could look into all the crashes of old airliners of other makes or models for evidence that they were misloaded freighters. I do not think I will bother.
I agree I have overstated the problem, after reading through the ASN Aviation Safety Database for the 747.
As it happens the two hull-losses that I had in mind are not straight-forward arguments for self-weighing: MK 1602 at Halifax 14 Oct 04 and Cargo B 3101 at Brussels 27 Oct 08. In both cases the physical loading was not in question; the data were mis-loaded by the flight crew. In those situations probably neither flight crew was enough on the ball to make prudent use of any cautionary information from the undercarriage.
Indeed, the Cargo B crew belatedly corrected their load figures, so an undercarriage cross check would only have comforted them; their disastrous mistake was not to recalculate the take-off speeds to fit the 100 tonnes extra weight they had stumbled upon.
As to the Bagram loss, I would insist that “improperly restrained cargo” is “badly loaded”, but that has nothing to do with self-weighing. Still, of the three cases, this was one where the captain could have felt “if they get that wrong, what else are they going to get wrong ?” To my mind the critical failure – and unbearably sad to tell – was that the aircraft loadmaster, on the ground at Bagram, seems to have seen that the restraints fitted at Camp Bastion were failing but could not bring himself to get them fixed before his aircraft again took off.
If I was to persist with my case, I could look into all the crashes of old airliners of other makes or models for evidence that they were misloaded freighters. I do not think I will bother.
Really? For any wind aspect from 0 through 359 degrees? And when the aircraft is at the gate with the wind swirling around all those buildings? so that some surfaces might see the full force of the wind while others might be blanked? With jetways and freight-loading kit further messing up the flow field around the aeroplane?
Oh yes, and don't forget to factor-in the tailplane trim position, because the wind will be producing loads on the tailplane as well as the wings...
PDR
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Well yes really.
We are talking about a check figure not primary planning information. A crew would be ill advised to take a reading in the hurly-burley you have in mind or, having taken such a reading, would be free to discard it.
We have been told of the ground installation at Bogota. I expect to be told that it is/was positioned somewhere along a long open taxiway.
A built-in system can be read at whatever point the crew finds the least turbulence.
I would be amazed if it was difficult or expensive for an aircraft maker to model the ground effect of surface wind on a free standing airframe.
I wait for Ex Cargo Clown #27 or Tower Dog #28 to tell us whether surface wind was even considered in using the installations they know of.
We are talking about a check figure not primary planning information. A crew would be ill advised to take a reading in the hurly-burley you have in mind or, having taken such a reading, would be free to discard it.
We have been told of the ground installation at Bogota. I expect to be told that it is/was positioned somewhere along a long open taxiway.
A built-in system can be read at whatever point the crew finds the least turbulence.
I would be amazed if it was difficult or expensive for an aircraft maker to model the ground effect of surface wind on a free standing airframe.
I wait for Ex Cargo Clown #27 or Tower Dog #28 to tell us whether surface wind was even considered in using the installations they know of.
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. I wait for Ex Cargo Clown #27 or Tower Dog #28 to tell us whether surface wind was even considered in using the installations they know of.
loadsheets weight and balance
we mostly used notional weights 75kg males 65 kgs females
can't remember child weight 35 kgs?? and 10 kgs for an infant
bags were 15 kgs
so an example loadsheet would look like 48M 42F 15C 2I plus 108 bags
plus 128 kgs of freight
= your actual load sheet payload - plus add the crew and catering
all in kilos (sometime in lbs which was a pain in the arse)
TOB 105 + 2 INF
occasionally the baggage was actual weights used (weighed on scales at check in)
and mail and bulk cargo was all weighed and manifested
sometimes if the size of the baggage and type of flight was abit abnormal - then maybe we would calculate everyone as a male at 75 kgs + 20 kgs bag weights for all pax - depending on what skipper wanted
oil rig workers and ski flights always drew attention
All cargo freighter a/c - all palleted/ULD or bulk cargo was actual weights plus add the weight of a ULD or pallet as well (which were standard weights)
all quite simple maths really
one of our 707's had a CofG MAC meter in the cockpit which was pretty accurate - i think it worked off the nose wheel but cannot remember
BTW what are today's notional pax weights? - I assume they have increased somewhat than what I have quoted above
we mostly used notional weights 75kg males 65 kgs females
can't remember child weight 35 kgs?? and 10 kgs for an infant
bags were 15 kgs
so an example loadsheet would look like 48M 42F 15C 2I plus 108 bags
plus 128 kgs of freight
= your actual load sheet payload - plus add the crew and catering
all in kilos (sometime in lbs which was a pain in the arse)
TOB 105 + 2 INF
occasionally the baggage was actual weights used (weighed on scales at check in)
and mail and bulk cargo was all weighed and manifested
sometimes if the size of the baggage and type of flight was abit abnormal - then maybe we would calculate everyone as a male at 75 kgs + 20 kgs bag weights for all pax - depending on what skipper wanted
oil rig workers and ski flights always drew attention
All cargo freighter a/c - all palleted/ULD or bulk cargo was actual weights plus add the weight of a ULD or pallet as well (which were standard weights)
all quite simple maths really
one of our 707's had a CofG MAC meter in the cockpit which was pretty accurate - i think it worked off the nose wheel but cannot remember
BTW what are today's notional pax weights? - I assume they have increased somewhat than what I have quoted above
Last edited by rog747; 11th Feb 2018 at 08:17.
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Well yes really.
We are talking about a check figure not primary planning information. A crew would be ill advised to take a reading in the hurly-burley you have in mind or, having taken such a reading, would be free to discard it.
We have been told of the ground installation at Bogota. I expect to be told that it is/was positioned somewhere along a long open taxiway.
A built-in system can be read at whatever point the crew finds the least turbulence.
I would be amazed if it was difficult or expensive for an aircraft maker to model the ground effect of surface wind on a free standing airframe.
I wait for Ex Cargo Clown #27 or Tower Dog #28 to tell us whether surface wind was even considered in using the installations they know of.
We are talking about a check figure not primary planning information. A crew would be ill advised to take a reading in the hurly-burley you have in mind or, having taken such a reading, would be free to discard it.
We have been told of the ground installation at Bogota. I expect to be told that it is/was positioned somewhere along a long open taxiway.
A built-in system can be read at whatever point the crew finds the least turbulence.
I would be amazed if it was difficult or expensive for an aircraft maker to model the ground effect of surface wind on a free standing airframe.
I wait for Ex Cargo Clown #27 or Tower Dog #28 to tell us whether surface wind was even considered in using the installations they know of.
One has to watch for some fiddling of reported weights from some shippers. Some packed their containers at their facility but of course, our Air Freight people weighed each one as it was received, or at least so they assured us they did so. When a loader-lifter refuses to raise two LD-3's, its hydraulics screaming in protest, one gets suspicious. Each had a weight of 3200-lbs chalked on it as testimony that our people had weighed it.
Fortunately the Chief Pilot at JFK was walking the ramp with me and he insisted they take the two back to air-freight for "reweighing". Each one of those two LD-3 exceeded 11,000-lbs, somewhat in excess of the 3500-lb limit. They were packed with flat sheets of aluminum stamping going to a factory in Puerto Rico for bending and assembly into TV sets. Our local Air Freight department suffered a change in local management as a result.
We had some B747-100's that had strain gauges on the gear feeding a built-in W&B system. They never worked very well and ended being deactivated.
Fortunately the Chief Pilot at JFK was walking the ramp with me and he insisted they take the two back to air-freight for "reweighing". Each one of those two LD-3 exceeded 11,000-lbs, somewhat in excess of the 3500-lb limit. They were packed with flat sheets of aluminum stamping going to a factory in Puerto Rico for bending and assembly into TV sets. Our local Air Freight department suffered a change in local management as a result.
We had some B747-100's that had strain gauges on the gear feeding a built-in W&B system. They never worked very well and ended being deactivated.
