Peter wrote:
Same in PA28s; with 3 modern size adults they are over max.
Not in my club’s Archer II. I have done a 2 hours’ flight with 4 adults, no baggage, and obviously not full fuel, and we were under MTOW.
Flyer59 wrote:
It is more important to understand the POH than to follow it like bible down to 1 percent.Every POH i know contains mistakes too and is never the “whole truth”. For example the SR22 POH says 77 knots for short field landings, but every specialist will use 77-1 knot per 100 lb below MTOM.
Approach speeds are not in section 2. The only V speeds in section 2 for your plane are VNE, VNO, VO, VFE and VPD. So yes, I agree, you have to understand the POH.
The limits in section 2, you have no way to know how they have been derived unless you speak to the engineers that did the certification, as I wrote earlier.
We recently had another thread called “normalisation of deviance” – this is a fantastic example.
This means activity where rules are routinely breached, typically because “nothing ever happened / will happen / it won’t make a difference”. This can ultimately lead to increasing tendency to push the limits to the point the space shuttle blows up, the aircraft mows down the localiser antenna below minimum in fog, or you stall out of the clouds full of ice.
The key word is routinely. There is nothing wrong with deviating from a rule after thoughtful consideration and weighing the risk (run out of fuel if winds are too strong vs. run out of runway when taking off), proportionality of cost (wear and tear, not making the trip or getting there a different way / taking longer), the mitigations (2 miles of tarmac)… as long as it is a well considered exception, and indeed regulations provide ways to do so, but put checks and balances to prevent this from becoming a routine incident. Such as ferry approvals. They don’t exist because the approval makes the operation safer, but it makes it non-routine and enforces a minimum level of thoughfulness…
The authorities want the bar for these things to be very high, and I personally think the bar we all set for ourselves should be very high. This not just for the legal imits – there are many places where you have a bar (personal limit or recommendation) that you can legally exceed, but should do so only on an exceptional basis.
So I would say:
On a personal note – I don’t exceed MTOW in my private flying, as I tend to obey the +2 rule – always have 2 more seats on your aircraft than you need for the full range mission, so you can have the occasional extra friends on board and still go somewhere, but weight and balance is a non-issue on most flights. So I make sure the issue doesn’t arise in the first place.
Those who know that I instructed a bit can read into the careful wording of the above statement what they wish…
I agree 100% to this well balanced and sensible approach.
(Both the SR22 POH and FOM (Flight Op Man) say that 77 kts is the right short field speed. But it is not, and the 77 kts are useless for many runways in Europe. Try the 77 knots in Helgoland or even LOWZ, it’s way too fast for both!)
The authorities want the bar for these things to be very high, and I personally think the bar we all set for ourselves should be very high. This not just for the legal imits – there are many places where you have a bar (personal limit or recommendation) that you can legally exceed, but should do so only on an exceptional basis.
So I would say:
If you exceed the MTOW very occasionally for a good reason with due consideration – you decide how important the law is for you, but it is not necessarily unsafe.
If you regularly fly above MTOW as a matter of course – ouch. You have bought the wrong aircraft.
I think this is very wise advice. I worry about people who regard MTOW as a suggestion. Crossing the Atlantic in smaller aircraft, there are some rules you may well have to interpret liberally. But this is usually done in a serious preparation and after very careful consideration of the consequences. Of course many rules can be broken safely. But a culture of always breaking the rules has real safety implications.
(And F59 I am not suggesting you fall into the latter camp – it is a general comment).
I don’t care what “human nature” is, i only care about my own nature. And i am the very careful type who will check the weather like i was paranoid and never take chances. Actually my wife calls me a “paranoid” when it’s about safety …
It is a matter of character and discipline. In 22 years and 1500 hours i have not had one critical situation (the worst was a door popping open sucking out my VFR chart :-)) … and one time i forgot the pitot cover and aborted the t.o. “Speed … alive? Not!” :-)
When i write that the two times i flew the 310 hp Cirrus with 30-20 lb too much, were sn exception, then you could understand that i am not the type who will “try more” than the 30 lb.
I fly one of my aircraft regularly at up to 5% over gross. Two things underlie my doing it: the first is that a later structurally and aerodynamically identical variant of the plane has a 10% higher certified gross weight (with higher power), and the second is that my aircraft’s climb performance at that weight is acceptable for my operations. The extra 5% provides substantially greater utility and safety because it allows two grown men without bags to carry three or four hours fuel. There are no flight manuals for the aircraft that supply useful aircraft performance data (its too old for that), so all performance issues need to be determined experimentally regardless.
I once wrote on the Socata group, in a similar thread, that I fly 30% over max.
It gives me a useful 30% increase in Va.
A number believed it.
That was before I got thrown out 
coming back to the healine i think for some planes the “follow up” issue when u are above MTOW are much more critical to the flight such a CG
in my case with a Beech Bonanza it does occupie many posts on Beech related forums
it does bother me as well a lot to have the CG within the limits
i will also next week weigh my plane again to check the numbers for the calcs come from the “real” world
172driver wrote:
I think these figures are still valid and they obviously are pure fantasy.
Actually I don´t think they are, they are long standing statistical mean figures. I once heard a presentation about it about 20 years ago. I do remember however that we used to start with 75/65/35/10….
Flyer59 wrote:
It is more important to understand the POH than to follow it like bible down to 1 percent.
It is important to understand it. Our POH´s are comparatively simple and pretty straightforward to understand in terms of limitations and performance. At the same time, understanding why it was done that way also means knowing that the limitations are there for a reason.
Flyer59 wrote:
Every POH i know contains mistakes too and is never the “whole truth”.
Yes. Some of them are outright wrong and written by marketing folks, at least for older planes. Yet, that is one more reason why I´d keep to the weight limits (and even more important the balance envelope)! Any plane in our GA range is notoriously short on payload. So believe me, they went as high as they could justify with the MTOM. Exceeding it works if you do it in cooperation with the manufacturer and the CAA, but it is the exception and not the rule.
Many earthrounders and also flights like were described here work that way, with ferry tanks and (approved) MTOW supplements. The most important thing to look at there is clearly to stay within the balance envelope and to know what the weight increase will do to the performance. Otherwise you end up like a dear friend of mine who did not survive his record attempt in a overloaded plane.
