Probably irrelevant to us here flying light airplanes, but AFAIK in many cases the displaced threshold is the place from where the runway strength is sufficient to handle the loads of large aircraft landing. Might be relevant to some here who fly a lot into grass strips.
Ibra wrote:
as long as they don’t have “X” on them it’s legal
I can quote you in court, I assume? ;-) What about the yellow chevrons of a stopway, would you land on those? Or a lead-in taxiway aligned with the runway, would you land on that?
Flare where you like. What I don’t think you should be doing is putting the wheels down before the start of the area designated for landing, but that’s up to you of course. Like I said before, I might do it if I felt it improved safety in a particular situation but I certainly wouldn’t broadcast it on YouTube if I did. More likely, if things were so marginal I needed the area before the displaced threshold then I’d probably go somewhere else. And of course, if LDR > LDA then you’re operating in contravention of the POH – assuming it has one that gives distances.
@Graham, from CAP168:
Landing Distance Available (LDA) The distance from the point on the surface of the
aerodrome above which the aeroplane can commence its landing, having regard to the
obstructions in its approach path, to the nearest point in the direction of landing at which
the surface of the aerodrome is incapable of bearing the weight of the aeroplane under
normal operating conditions or at which there is an obstacle capable of affecting the safety
of the aeroplane.
So that is a point over which an aircraft can commence landing, so it is not a landing run available…
re: where could you land
I’ve been taught the following way:
1. You cannot take/off or land on yellow shevrons (safety area).
2. You cannot land on starter extension.
3. You can land before or after displaced threshold.
As long as there is a clear distinction in pilots’ minds between 2 and 3…
AFAIK displaced threshold means there are obstacles which (if they are avoided AND the designated angle is followed) prevent the aircraft from reaching the area before it. If you fly a smaller plane and/or steeper angle then should be OK.
a lead-in taxiway aligned with the runway, would you land on that?
I am not aware of any restrictions on that?
As always getting ATC clearance does not mean it’s legal but it’s a good proxy to what is accepted
Ibra wrote:
a lead-in taxiway aligned with the runway, would you land on that?I am not aware of any restrictions on that?
Ibra, you are not supposed to – it might be designed to sustain the load as associated with aircraft taxiing and not landing…
Wee are talking about operations on unlicensed runways? land at your risks…UK CAA now even allows PPL & CBIR training under NCO in unlicensed runways
Ted wrote:
I would agree if the area is marked as unusable by crosses, but if it is just a displaced threshold how is it not part of the runway? There is a clue in the name
It is not Xed because it can be used for take off.
Displaced Threshold is for a reason – to allow clearance for something, e.g. vehicles and people. I have heard of someone being MOR’d to the UK CAA for touching down on one.
I have once touched down on one – legally, as the throttle locked on short final and I could not reach the threshold, (by a metre).
Maoraigh wrote:
Displaced Threshold is for a reason – to allow clearance for something, e.g. vehicles and people. I have heard of someone being MOR’d to the UK CAA for touching down on one.
@Maoraigh, are you sure you are talking about a displaced threshold and NOT the starter extension? They look similar! :)
To my knowledge, no one was punished by the UK CAA for landing on a displaced threshold, but I know of two pilots that been warned sternly by the UK CAA for landing on starter extension (as it is in effect landing on a taxiway). MORed doesn’t mean punished.
