CHIRP and Standard Weights (Masses)

[Dengue_Dude]

The latest CHIRP has recently arrived and it is interesting to note that incidents are highlighted concerning Standard Weights (Masses) for pax and baggage.
Note the SRG statement is as woolly as one expected. CHIRP points out that the first respondent was not only justified but also praised his/her assertiveness.
Most of us are well aware that when we're FULL or at max ZFW, we're generally 'comfortably' too heavy. But hey - that's why we do Net performance isn't it? NO it isn't, that's supposed to be safety factoring NOT for the company to make money out of.
We know, the Handling Agents know, the Company know and even the regulatory authorities know. What is done? Nothing. But don't worry - the CAA SRG have got a committee.
What happens is that generally if you complain you get fobbed off. I asked on a couple of occasions that the aircraft baggage was check-weighed - ho ho, three chances of that happening. FAT, SLIM and NONE.
The fact remains that if we operate safely concerning passenger, baggage and freight weights we are going to suffer commercial disadvantage (I am talking of FULL or particularly long-range sectors here). So if you become 'assertive' or kick up a fuss you become a marked man/woman.
Yes the rules are clear, if there's any doubt - weigh the pax/baggage/freight etc etc.
The procedure is in the Ops Manual, JAA Regulations, Handling Agents SOPs - but try to do it and see firstly if they even CAN and secondly wait for your collar to be felt.
I suggested a few years ago that our Weight and Balance manager (in a money-losing large charter operator based in Manchester) do a percentage check of our customers and their baggage to 'cover his xxxx' in the event of an accident and also highlight the differences in actual and standard weights. Needless to say he didn't. They already know.
Will it take a body count in our country before someone actually bites the bullet and gets on with this - the body count has already happened in the USA (albeit a commuter twin)?
It is SO hard not to be cynical. I get sick to death with the assertion that flight safety is paramount. It isn't. That's just for public and media consumption.

[EESDL]

Nice RANT - hope it makes you feel a bit better.
So, how long are you going to keep quiet?
May I glibbly suggest that it will be a tad too late you after you stuff in:-(

[jmc-man]

Hey Dengue_Dude,

Interesting post, and a subject close to my heart for various reasons.

The concept of using standard weights is always an anathema to pilots, although we seem to apply our concerns selectively.

You make a point about use of standard baggage weights, but in reality they are small potatoes compared to average passenger weights. The problem is, it is wrong to just seperate out the bag issue, without considering the passenger weights as well.

And for that matter, how much does you empty aircraft weigh? And how often is it checked? From experience, a well used jet aircraft can increase in weight by over 100 kgs a year. Don't believe me? Ask any heavy maintenance crew how much crap they remove from aircraft on major checks.

Whether you like it or not ( and I have my personal views) the use of averages for large transport aircraft is reasonable and practical and is well covered in the performace and weight margins applied to the aircraft by the manufacturer and operating safety margins set out by regulatory authorities. And I'm prepared to bet that if you weighed everything you put on an aircraft, and compared to the " average weight" calculation..you would be pretty close.

Now, lets discuss the weight change that takes place when passengers eat the catering. :)


JMC Man

[J.O.]

While the rant is a bit strong, the issue is a significant one. Here in the Great White North, a fatal accident involving a heavily (i.e. over) loaded Cessna Caravan, caused Transport Canada to significantly increase the approved average weights for passengers. Males were increased by some 10%, and females were increased by up to 20%:eek: . As an example, if a carrier chose to use these approved weights, the average payload on an A320 in charter config (180 pax) would increase by 1500 kgs, or more! TC allows the carriers to conduct a weight survey to determine a "company" average, which is submitted for approval. No guidance was given with respect to sample size or statistical methodology, but it's sufficient to say that a survey must be completed over several days, while sampling several flights per day out of many different stations. Most companies have done the survey, and their approved average weights have ended up being less than the Transport Canada averages, but they are higher than the numbers that were used previously (which were the old TC averages). So, the carriers now find themselves in a position of having to ammend their payload capabilities, and some may even have to remove seats as a result. For the pax, less seats may mean more leg room, but it will also mean higher costs for travel. Given that there has not been any recent large transport accidents in Canada where weight was an issue, the airlines are no doubt less than pleased, but I can see why the regulators changed the rules.

[simfly]

Offshore in the UK, we have been using a new standard weight for pax which was implemented by the CAA. The only thing is, due to the massive increase, we're saving so much by using actual weights, infact, the average pax weight we're getting is almost exactly the same as the old standard weight :confused:

[Dengue_Dude]

Yes it was a rant - I've been doing this for over 30 years and the inertia associated with this issue is wearing.
I fully agree with the assertion that the aircraft's basic weight changes between manufacture and D checks - but you know, that particular phenomemon is not really controllable and is an eloquent demonstration of why we should plan NET performance take offs.
The weights of average passengers changing dependent upon what kind of flight they are on is flawed. Why allow 13kg when the ticket says 20kg can be carried. Have you actually looked at some of our customers at check in - they can barely lift their luggage - consider the 'Heavy Baggage' campaign I last saw in action at LHR.
For example, whilst not fat, I weigh more naked than the loadsheet allows for me and my nav bag! (Not a nice thought that).
Are 'we' not concerned with levels of obesity (an increasing morbid obesity) in this country? Yes provision exists for obese passengers to be weighed, BUT how often is it done? I have NEVER seen it shown on a loadsheet because when I've checked by mulitplying number of pax by standard weight - it agrees.
Mike's point about the relative proportions of All Up Weight in large and smaller aircraft is well made and sustained. In this case the concern with respect to correct handling and loading of ULDs is critical especially concerning aircraft trim.
However we will STILL operate (especially but not exclusively in the charter market) long or full sectors over weight - everyone knows and nothing is done. At the subsequent board of inquiry - who will suffer (in particular)?
As for 'when am I going to say something', I've reported occasions when this was blatant through the various company's Safety Reports, I've gone to see flight safety officers etc etc
On other matters I've CHIRPed about a particular airline's low safety standards - warning of an imminent major crash. It happened a few months later resulting in a wide bodied aircraft hull loss - miraculously with loss of life. [The edit: with NO loss of life - sorry].
The result of these reports? Nothing - some form of words that was woolly enough to contain the message 'we hear you' and that's it.
So - do I feel better? Yes actually I do. I thought that was the purpose of these forums . . .
When it happens - and it's only a question of time, especially with the A380 coming, at least I know I tried.

[212man]

I'd like to see how the actual weights compare with standard weights on the Lagos run!:uhoh:

[CD]

TC allows the carriers to conduct a weight survey to determine a "company" average, which is submitted for approval. No guidance was given with respect to sample size or statistical methodology, but it's sufficient to say that a survey must be completed over several days, while sampling several flights per day out of many different stations.
Is this the guidance that you are thinking of:
R745.39 - Implementation of Weight and Balance System (http://www.tc.gc.ca/CivilAviation/commerce/manuals/guidance705/division3.htm#745.39)
R744.32 Weight and Balance Control Program (http://www.tc.gc.ca/CivilAviation/commerce/manuals/guidance704/division3.htm)
S743.37 Weight and Balance Control Program Aeroplane - Implementation of Weight and Balance System (http://www.tc.gc.ca/CivilAviation/commerce/manuals/guidance703/division3.htm)
There is information on the establishment of air operator standard weights in these sections. It's been available for quite a number of years but not everyone knows its there...

[john_tullamarine]

Two important factors for the use of standard weights -

(a) the sampling analysis upon which the standard weight is based must be relevant to the population being carried. ie if the analysis is based on little ol' ladies leaving church on Sundays .. but you routinely carry sumo wrestlers .... then the system should be seen to be flawed.

(b) the number of seats is very relevant in that there will be a variation in the population weights, generally represented by the standard deviation parameter. The nature of the beast is that, for small samples, the effect of the variation can be significant while, for large samples, it tends to even out.

Hence, if one weighs all the passengers and both (a) and (b) have been addressed sensibly .. the C172 load might show a significant variance to the presumed standard weight while the B747 will, likely, be so close to the standard weight that it doesn't matter.

For this reason, it is appropriate to use a higher standard weight for small aircraft and a more "reasonable" standard weight for larger. Australia, for one, adopts this policy, based on a study done some years ago by one John Klingberg who was the man looking after weight control, amongst other things, at that time.

It always remains an option to weigh the passengers and, at the other end, there is a sensible responsibility not to use standard weights when such use patently is inappropriate ... although we all know that this latter consideration is not observed in many quarters.

[Dengue_Dude]

Whilst the comments above are both informative and informed - and with which I personally concur, I feel they've missed the point I was trying to make.

1. I am not denying there are procedures in place to catch the gross (sic) errors in Weight and Balance and sensibly these vary with the aircraft's size as their payloads are disproportionate.

2. Undeniably the medical profession inform us that we (certainly as Western Europeans and North Americans etc) are getting heavier (if you doubt that - look in your wardrobe!)

3. The point I'm stressing (perhaps overstressing?) is that the standard masses are not realistic, personnel-wise and baggage. This isn't critical on larger aircraft that are not at extreme range or at max ZFW. But the discrepancy is significant when either of the last two points are relevant.

I'm not particularly into conspiracy theories, but the fact remains that the procedures in #1 above are rarely if ever invoked - personally I've NEVER seen it happen as applied to passenger weight. There is only one reason, and that's money, it has nothing to do with Flight Safety which 'we' say is paramount. Wake up and smell the roses.

I won't even go into my experiences in the third world where 'excess baggage' is declared at the point of sale and a deal struck between the handling agent and the passenger - then the baggage is declared 'standard' and the money pocketed.

Still, as declared above 'Nice Rant' and I do feel better.

[john_tullamarine]

Dengue Dude,

Have to disagree in the main or, at the least, suggest qualifications to your comments.

(a) these vary with the aircraft's size as their payloads

The proportional consequence of error may be greater for the small aircraft but the concern is passenger numbers, not aircraft size, per se

(b) we (certainly as Western Europeans and North Americans etc) are getting heavier

No doubt about it. Hence the absolute need for relevant population studies to schedule standard data. For instance, the common 170lb number for adult males is based on a study from the 40s (memory could be failing me but I'm not going to dig out the data from the archives to check) based on US Army statistics. There is no reason why more appropriate studies cannot be done so that the data are relevant.

(c) the standard masses are not realistic

.. only if the population statistics from which the standard masses are developed are based on a non-representative population. Your criticism needs to be directed at the implementation of the procedure, not the philosophy. If the population statistics are relevant, and procedures are in place to guard against inappropriate application in specific circumstances, then the use of standard masses will be fine.

(d) I'm not particularly into conspiracy theories

The whole philosophy depends on honourable protocols. In the event where fraud might be relevant, then weighing the loads on the day can be fiddled in a similar manner .. so the problem still remains.

[Dengue_Dude]

Agreed across the board.

My problem with it is that whilst the procedures exist - more often than not, they are not USED.

If flightcrew invoke them or kick up about it - you become very unpopular very quickly.

I believe that the industry 'does not want' the standard weights to be reviewed as the findings are likely to have a direct effect on profits.

I also appreciate that this is a circular argument, so having said my piece and aired the subject, I will return to silence on the topic.

A sincere thank you to those of you who took time to discuss the issue.