and flat spotting the tyre(s) needs only a second or so of locked brakes.
Quite. Been there, done that, and I’m sure I’m not the only one. It’s one reason why I refuse to try for truly minimum landing distance. I could get down to about 700 feet when I practised regularly in my TR182, but that was still with gentle braking.
One of my instructors explained why you shouldn’t try to match the landing distances in the POH. “They’re factory pilots, they do it all the time, and what’s more they have a truck standing by full of replacement tires. You don’t.”
As for squat switches… sure, in theory. And how are you going to find out when it has failed? Correct, by putting the gear control up while on the ground. So don’t!
The T6 (aka Harvard) is retractable but does NOT have a squat switch. Apparently – and this is NOT from personal experience – if you put the switch up while on the ground, it will obligingly retract the gear, leaving itself sitting on its belly and you looking very silly.
Peter wrote:
Antilock brakes would be the proper solution
Available if you buy proper aircraft… stay away from the cheap stuff Peter 
Most of my early flying was done on an aircraft without brakes. I still sometimes forget that I’ve got them.
johnh wrote:
They’re factory pilots, they do it all the time
It is often said that you shouldn’t trust POH performance values because they were obtained by “factory test pilots”. OTOH, the certification rules make clear that you should not need any special skill to achieve book performance. Also, pilots who do use special techniques (such as in precision landing) do achieve shorter landing distances than book figures.
NicR wrote:
that there is a pressure sensor on the gear
The pressure sensor only works when there is weight on the gear. If there was sufficient weight on the gear, the brakes would operate as desired. But retracting flaps shall increase weight on the gear, which carries only part of the aircraft weight, because the wings still produce lift. So it may be the case that the pressure sensor still is not operated during flare, and the gear may collapse, even in a TB20.
The Rallye short takeoff: start with zero flap, full flap at 85km/h, rotate abruptly. Interestingly, the manual doesn’t mention retracting flaps for short landings. It does say to keep the stick fully back to lift the nosewheel, and I’ve found the extra aerodynamic braking from fuselage and stabilator does make a difference to the landing roll on nosewheel aircraft.
Beringer brakes are anti-lock
Well, a lot of these procedures are not sanctioned by the POH. Unless they are prohibited, there is often an advantage in using them.
And yes, this is very airframe-specific, even the same aircraft will have different applicabilities depending on circumstances (runway, weight and balance, wx…)
If you take, for example the altiport landing thread that this was discussed at, well, no POH (and no formal guidance I have found anywhere) will give you figures for landing or take-off distance on 15% slope…so how do you takle it?
Even just discussing a grass landing on flatland, no POH will give you precise data on distances for your runway, your conditions, your day…just rough guidance. So what do you do?
Do you treat the POH like the Gospel and simply do not operate unless it is precisely explained therein?
Of course not: you exercise reasonable judgement based on your experience and that of others.
In our case, the P210 POH does sanction retracting the flaps after landing on short field landings.
Peter wrote:
brakes are usually strong enough to lock the wheels, and flat spotting the tyre(s) needs only a second or so of locked brakes.
The “strong enough to lock the wheels” of course depends on how much weight you have on them and what the runway surface is, but in any case, ask me how I know about that )?
Ibra wrote:
Who uses breaking when landing tri-cycles?
99% of my landings I don’t use heavy braking, and 80% nothing but a tad prior to runway turnoff, but 90% I now raise flaps after landing.
It is a matter of removing weight from the nose gear and ensuring braking is available, even if not necessarily used, like in the above example.
The former is but essential for me on grass runways, long or short. I cherish my prop&engine too much, and I did read @Peter’s story of his prop on a brand new aircraft years ago…
I do it 100% of the time in the PA-28’s I fly. Johnson bar, low risk to confuse it with the gear lever (when there is one).
Main advantage is the plane really stops flying. At an airport with more or less constant crosswind, no risk for the upwind wing to go up.
On gravel/grass, you also reduce the risk of the main wheels throwing loose stones at the flaps.
Better braking comes last.
Better braking comes last
On tri-cycles yes
In tailwheels hard breaking (symmetric or asymmetric) when you have lost elevator/rudder authority is a receipt for disaster (better do right after touchdown or punch & jab format at the end)
Antonio wrote:
Do you treat the POH like the Gospel and simply do not operate unless it is precisely explained therein?Of course not: you exercise reasonable judgement based on your experience and that of others.
The challenge with “judgement based on experience” is that we almost always lack the required experience on how it works when we do things differently. We normally do things as we learned in training and even if we try e.g. an alternate landing technique, we intuitively compare the technique we have practiced hundreds of times with that which we just tried the first time. Not a very good experience.
If you ask a professional athlete on the experience of changing something fundamentally on the basic technique, they will always tell you that it takes a year of getting worse until it gets better.
Retracting flaps while on ground roll is such a fundamental change in a complex technique. Minimum ground roll requires applying maximum non skid braking action from the very moment the airplane touches ground. The effect of applying best possible brakes is clearly higher than the effect of additional weight on wheels. Therefore acting on the flaps must not interfere with optimal braking.
It has also been discussed before, that if looking at landing distance and not ground roll in isolation, many other factors (optimal glide slope, optimal speed, etc.) are even more important so that any mistake there due to “preparation to retract flaps” would overcompensate any positive effect.
If retracting flaps in ground roll has any effect, it obviously has it only in the very first couple of seconds – after that the speed is so low anyways, that even with faps there is little lift left. For myself finding the right braking pressure is enough of a challenge in these seconds so that I don’t fiddle with the flaps or anything else.
P.S.: Obviously we are only talking about planes with manual flap levers. Electric flaps retract too slow anyways to make a difference in that first seconds.
