boscomantico wrote:
While I don’t know how they do it (either weigh them or just “calculate” the empty weights based on exact model and options installed) but either way, I am confident that the numbers are quite accurate.
I have seen many mistakes in “Computated” W&B sheets since there are so many equipment options that may be installed or removed by either the Factory, the Dealer or any other entity that happens to work on it.
At any rate, when I wrote “NEVER been weighed” I meant exactly that, most have never actually been on scales !
achimha wrote:
If I go on a VFR trip with 3 guys and a C172 I might have two options:1) Plan with 15 min fuel reserve: LEGAL
2) Fly 50kg over MTOM: ILLEGALI would always go for 2) because it’s safer and smarter. So you can’t reduce this to the legalities, you have to know what you’re doing.
That’s plain non-sense. There is always option 3 and 4 and 5
3) Don’t go
4) Reduce your weight
5) Choose a more appropriate aeroplane for the trip and the “payload”
Only 3,4,5 are safe and legal.
achimha wrote:
And putting people on a scale just doesn’t work. I have rarely ever seen that being done. It just doesn’t feel appropriate and there is a great reluctance, it’s basically an insult to your passengers because you don’t trust their statements.
We always put people on scales and it works a treat. If you can’t present your required responsibilities to your passengers in a “professional” way you have no place in the cockpit. You’re the expert. They just want to be safe.
achimha wrote:
So you’re making a statement about 80% of the PPL instructors? I’ve mentioned the C150/C152 training fleet before. It all starts there!
Not sure what you’re talking about here. Are you stating it’s regularly done by flightschools and they get away with it time and time again?
Archie wrote:
Not sure what you’re talking about here. Are you stating it’s regularly done by flightschools and they get away with it time and time again?
Your level of surprise shows me that I should not take your previous statements too serious…
Michael wrote:
I have seen many mistakes in “Computated” W&B sheets since there are so many equipment options that may be installed or removed by either the Factory, the Dealer or any other entity that happens to work on it.
I’ve seen aircraft reweighed after equipment had been removed or installed, with a new weigh report produced. There’s probably regulations for engineers for when that is required.
achimha wrote:
Your level of surprise shows me that I should not take your previous statements too serious…
I guess I’ve only attended good flight schools then! Time for the regulator to step in…
Time for the regulator to step in…
Absolutely. It is widely known that aviation suffers from an appealing lack of regulation, certification and bureaucracy 
…
It’s probably accurate to say that a C150 with two big blokes will be over max but a PA28 with the two should be ok.
OTOH a lot of flight training is done with little fuel because they are not going far.
My PPL training certainly involved a lot of scarily low fuel but I went along with it IF an instructor was present on the plan that if we ran out I would fold up my arms and leave him holding the baby. When I flew solo I used to fill up and got some bollocking for it.
There’s more than one club/flying school nearby where the appearance of the CFI made me wonder if the C152’s aren’t overweight even without a pupil on board…
And yes, a PA28 does better but as a fourseater that is a peer to the C172 not to the C152.
blueline wrote:
Absolutely. It is widely known that aviation suffers from an appealing lack of regulation, certification and bureaucracy
You’re right 
A lot of that has to do with overregulation and “arse” covering, however the MTOW limits in the POH are based on safety calculations that have a defined (and agreed) safety margin, and this limit results in the aircraft performing as presented in the POH (at least at certification time).
Most of the limits on the Airspeed indicator are derived from the MTOW. The structural design of the aircraft is based on MTOW, the maneuvring limits (g-limits) are based on MTOW etc. etc. etc. etc.
I would have thought it is a no-brainer to adhere to the MTOW as stated in the POH, because you lose a lot of layers of protection of you decide to go above and you are basically a test pilot.
But apparently a lot of people don’t take the rules so literally… and a lot of the argumentation comes down from one of the hazardous attitudes (anti-authority, invulnerability, macho).
I’m not saying W&B is an exact science, but it is easily possible to get is pretty much dead on, if you put a little effort into it. And if you can say “No” to your passengers if the payload turns out to be to great (another interesting personality trait…)
Regarding the statement “airlines always fly overweight”. May I point out that an A380’s MTOW is 575,000 kgs, whereas the 853 pax it could carry weigh perhaps 65,681 kgs i.e. only 11% of the aircraft weight. In a typical C172, the payload makes easily 30% of the MTOW. One person weighing heavier on an A380 will change nothing, and there will be some lighter people too like asians etc. But in a C172 it changes everything.
I know a number of airline pilots and they say airliners are not weighed. The W&B is calculated only, using a nominal passenger and luggage number. Their opinion is that they probably are overweight a lot of the time but it doesn’t matter because all the airports they fly to have much longer runways than is needed. The AOC margins for jets are massive.
I was surprised to hear there is no weight indication. In the 1980s I worked on a project which displayed the weight of a lorry, measured with strain gauges on the suspension. It would be straightforward to do this on aircraft landing gear because there are obvious points for attaching the sensors.
There are countless stories of obviously grossly overweight AOC departures. One A340 out of Gatwick was still at 1000ft AGL some 20 miles out (in Class G) – some years ago. There was some trouble over that. One guy I have flown with, a retired B747 flight engineer, has a scary (totally illegal flying, UK airline) story for every day of the year. So they seem to manage it, despite the passengers being only a small % of the MTOW. Or at least they used to; maybe the practices have been tightened in recent years.
It is worth knowing basics like if you are 1% heavier you need 2% more runway, a 1% runway gradient in your favour is worth x knots of tailwind, etc, and these rules don’t stop working just because you are 10% over MTOW. Sure the ASI markings are out of the window once you are over MTOW…
