Folks,
Surely the discussion is about theory versus acceptable commercial practice.
While I note the pejorative comment about "commercial pressure", the reality of sound regulation is recognising the potential for Catch 22 rules that set an unachievable benchmark for practical commercial operations. That is why we have a lot of so-called "despatch" rules (our planning rules) and their often less stringent cousins, the "operating" rules.
The aim of all of our loading rules is to operate the aircraft within certain limits. If we require an operator to weigh every passenger and every piece of baggage and to adjust the fuel weight for the tested SG by the actual temperature of the tanks, the ambient temperature and the delivery temperature so that it can be matched by the performance calculated for the average air temperature at the engine inlet height for the wind and circulation over the unshaded runway surface, corrected for the actual lapse rate for each obstacle clearance altitude, not forgetting the need for realtime analysis of actual wind velocity at every point of the departure flight path until clear of obstacles which, when modified by the performance decrement attributable to the handling pilot's control technique and accuracy.....etc, etc, we are never going to move another aeroplane again - anywhere!!
So we must compromise. We conduct statistical analyses of all sorts of things and we make regulatory (and commercial) decisions about acceptable risks. We survey passengers and we survey their baggage for weight profiles. We strike a figure, let us say 85%, and we come up with a weight for the individual (or the cabin baggage, checked baggage or nursed infants) that on 85% of occasions will be equal or greater than their actual weight. Then we analyse those individuals in various populations appropriate to the aircraft seating capacity to make sure that we have an appropriately low probability (say 10^-4) that the population actual weight will exceed the population standard weight. Note that in Australia, this sort of population analysis is what led to the increases in recommended standard weights for the smaller aircraft and the recommendation against standard weights in the common piston twins. And while we are at it, let us make the operator responsible for making appropriate adjustments for special charters or operations where the passenger complement clearly is not the normal distribution (mining sites, holiday charters, the world weight-lifting championships, etc).
Now we can plan the load and have the chance of despatching the aircraft in fairly quick time, knowing that the time and inconvenience saved by not weighing everything and everyone has an acceptably low risk of exceeding aircraft limits. All in all, a practical compromise that let's us move people and things with a modicum of efficiency.
Now, for all of you who report obvious failures to use realistic weights, make a stand to satisfy yourself that you are operating safely - there is no loyalty and no reward for overloading, just a lot of loneliness when you get caught or someone gets hurt. You don't have to fall on your sword - there are ways to get both your management and, if necessary, the regulator to act without becoming unemployed.
Aviation is full of compromises - just make sure that they don't get corrupted by ignorance or greed.
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Stay Alive,
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