Standard weights and a/c capacity
 

Could someone point me to a reference on standard pax/baggage weights and the seat capacity thresholds for these values to be used ?

Thanks

In Canada,

This: https://www.tc.gc.ca/en/services/avi...c-700-022.html

is an official reference.

The strength of seats an seatbelts varies with the certification basis of the aircraft (vintage). 170 pound occupant weight is a common starting point. Newer aircraft have higher design load/capacity requirements, and test methods.

Differs from country to country. Even in the same country operators are using different weights with regard to the regulations of course.

Yes, there likely are differences country to country. In Canada there was a well publicized accident more than ten years ago, involving a Cessna Caravan carrying hunters, where though the passenger count was correct, the weighing of the bodies showed that the plane was taken off quite overweight due to each passenger being more heavy than the "standardized" weight historically used. The Canadian AC was issued to remove a pilot's excuse for not knowing or thinking about non standard passenger weights.

I went through this flying jumpers decades back, where the operator wanted me to fly "weight" by occupant count, but I objected, pointing out that most hearty pumpers, when equipped with 'chutes and gear, went well over the assumed (head in sand) occupant weight of 170 pounds per person. I stopped flying for them.

To my pride and delight, my local float operator has a scale just inside the gate, and everything gets weighed.

Same thing when they design/test the 16g seats - a standard passenger weight is assumed. 16g is only assured up to that passenger weight - if you have a 300 lb. person sitting there, it'll fail at less than 16gs.

F = m * a :O

Thanks. I was wondering if different standard values or procedures were used for different numbers of pax. Statistically, you will be much more likely to be overloaded on a 12 seat a/c than a 300 seat a/c if you use the same standard value. Wondering if more conservative figures are used on smaller aircraft ?

Or weigh each passenger.

Yeah, and herein lies the inequity... If I STC approve a cargo net or other restraint for an item of mass which is not a person, I am required to placard a maximum mass to be restrained within. If I approve a seat, or a seatbelt, no such mass limitation - put in as much as you want! FWIW, my body mass is 185 pounds, and I ripped the seatbelt out of a 9G cert basis plane when I was crashed in it by my student two years ago. The seatbelt was found with a piece of broken off airframe aluminum still attached to it. My hip is not as strong as the seatbelt, they both broke....

Some thoughts -

(a) herein lies the inequity It would be totally impractical to restrict real world occupants to the design loads - but we can do that relatively easily for baggage and cargo. As an anecdote similar to yours, many years ago, a freight MU2 equipped with my design restraint system pranged with predictable results. The investigator gave me a call to let me know that the aircraft had disintegrated around my restraint system - allowed me to sleep easily that night .....

(b) one needs to keep in mind that, while the heavier folks end up with a "compromised" seat structure, the lighter might end up with more injuries due to higher accelerations, especially in dynamic seat installation helicopters where the download is spine-critical. Guess we just have to accept that there are no guarantees, only probabilities, swings and roundabouts.

(c) Some years ago, John Klingberg (then an Australian regulator engineer) prepared a very useful report which (eventually) formed the basis for the present protocol - https://www.casa.gov.au/files/2351pdf
John's report makes a good story for a sensible statistical approach to loading. If you can locate a copy, it makes interesting reading. Mine is someone in one of the older filing cabinets, gathering dust.

(d) As double_barrel suggests, the probability of misloading using standard weights is very much tied up with total numbers, as shown in John's report. Interestingly, in a previous life flying F27s, periodically we would have to weigh the load when fuel was really critical and we were after every last drop. With the typical 30-40 pax load, 170lb worked out real fine. That figure originally came from a study of North American Army personnel back in the 40s as I recall. I have the report somewhere ... As Dave indicates, one is better off weighing small loads ...

Yes, when I was flying home from Maseru, Lesotho decades back, I had a ticket, though was not told which day, as pax were boarded in the order they bought tickets, as the payload of the day would permit. The density altitude and winds were factored into the aircraft performance of the day, and the appropriate weight of pax boarded, in the order they bought their tickets. Inconvenient, but I have no way to criticize doing it right!

I had a similar situation with a highly modified Cessna 207 I configured and approved in 2005. The pilot eventually bunged it up, and crashed. The plane burned completely. I had the unpleasant, though necessary duty of discussion with the coroner exactly what killed the pilot. Though sadly, happily for me, the 700 pounds of equipment I installed and restrained right behind the two front seats did not hit the pilot from behind, but rather he succumbed to fire. Many of my approvals are for restrained loads in cabins, and I like to aim for much greater capacity than the 9G crash load requirement which is common to many older aircraft's certification basis.

In this photo of AWI's "Polar 5", a Basler Turbine DC-3 which I approve;


https://cimg6.ibsrv.net/gimg/pprune....48410b4dd4.jpg

The "father" of AWI's advanced radar systems, Dr. Heinz Miller, stands near the rack installations I approve with each new configuration, which include the diagonal restraint cables to the ceiling I insist on (covered in marker tape). I have load tested the racks, and they meet the crash loads without the cables, but I sleep at night, knowing that the cables are there too.

I reluctantly accept that we cannot regulate heavy weight people to not use airplane seats. However, somewhere there must be a balance of safety for those occupants who otherwise fall within the design assumptions for airplanes. It has been the case that entire multi seat assemblies have been torn off the the aircraft structure with the occupants still strapped in. In the case of a crowded aircraft cabin, this could affect other occupants, particularly around emergency exits. I complained once about a Canadian flight in which I was seated in an exit row, and the occupancy of the seat row across from me obviously exceeded the design capacity of the seat assembly. I could never have approved that combination. Transport Canada told me it was a political hot potato, which they would not take on. On the flight to Vancouver I rode yesterday, sure enough, two occupants of an exit row seat row, would have appeared to exceed the 170 pound per person assumption by at least double. I do respect Southwest Airlines, who have found a politically correct approach to limiting misoccupancy: Every exit seat row is placarded: "the use of seatbelt extensions in this row is prohibited". Forward thinking - one day, there will be an accident in which overweight occupants dislodge during a crash, and obstruct an exit path, and then this will be revisited. In the mean time, the new much higher dynamic seat load requirement helps...