Displaced Threshold
 

Hello everybody!
I have a question. After an aircraft has been cleared to land on a displaced threshold, can another a/c be cleared to cross the threshold? The crossing traffic is between the landing traffic and the Dis.THR and it doesn't penetrate the Inner Approach surface (Annex 14) and the VSS (Doc8168) and well below the traffic which is landing at an angle of 3 deg glide path.
Does it cause runway incursion? The distance between the THR and the Dis.THR is 741m, decision height is 120m.
I am confused because the touhdown zone is beyond the Dis.THR, so the THR is outside the LDA used for landing. I wonder if small traffic can cross the THR instead of holding short of the RWY until the landing a/c has passed the THR. ̣
When considering the height of obstacles, what surfaces should the constructor pay attention to? The Inner approach surface ? The VSS? The OAS? And how much is the acceptable deviation when an a/c taxi follow the taxiway centerline?
Thank you very much!!!

In the UK, when you have cleared an aircraft to land, the whole runway is available to that aircraft alone and no other traffic should enter it until after the landing traffic has passed.

Thank you for your information!
Could you please share with me any document about it? Tks a lot !! :)

At Princess Juliana International Airport in St. Maarten, landing aircraft flying above the traveler on the beach at a very low height.
What if we declare via NOTAM/ AIP that such aircraft as A321, A320, ATR-72 may cross the THR of the runway-in-use while there is a traffic approaching & landing on Dis.THR? Is it against any rules of ICAO/FAA?
Tks!!

Jeeesus ! are you serious ? and are you Vietnam management ?
If you really intend to do that do not ask permission to do this on PPruNe, ask the ICAO Bangkok office.

Devils advocate: Providing you have the correct vertical clearances under the approach slope, then why not?

Also devil's advocate - -

Clearly there is a distance at which a taxiway can be placed before the threshold of a runway which would comply with 8168 requirements and allow aircraft to taxi freely without reference to aircraft using the runway.
(I have no idea what this distance might be as I am not a procedure designer).

So if there is grass/sand/swamp between this taxiway and the runway threshold no one would question it.

The question is - if there is a concrete/asphalt surface between this and the displaced threshold of the runway (instead of grass) can the taxiway still be used independently of the runway?


Any examples from around the world might help PC.

what if the landing aircraft loses all engines due to birds and is committed to land?
with the loss of thrust and in a dirty config, they wont be able to keep the 3 degree to the touch down zone, and will land short, using the displaced threshold, oh wait, there's an aircraft sitting there!

Or for other airports, maybe a mountain, or a shopping centre, or, heaven forbid, especially if the Daily Mail will report on it, a school or hospital?

Gonzo : a runway is a runway , a taxi way a taxi way . Of course, providing you have a long displaced threshold you could use paint and shorten the runway , an could create a taxi way at the beginning of it , and displace the entrance of the runway clear of it to get proper height clearance. Then you need to change all the markings on the concrete and change the lights both on the new taxiway and remove those of the runway bit you closed , etc., and you do not have the original displaced threshold anymore as you cannot take off from a taxiway .The published data of your shorter new runway has to be changed as well everywhere and on the charts .

A NOTAM won't do it.

A number of states use a Runway Starter Extension, which you can commence the take-off from. (Although in Europe the proposal is for only 150m.)

Nothing to stop a state creating a Runway Starter Extension of 741 m

Bagheera : my understanding was that they want to cross the runway not line up .

I seem to recall it says in 8168 that an aircraft holding 250m or more before the threshold does not affect the OCH for landing traffic, but this is meant to refer to traffic not closer than 75m from the centreline, not on or crossing the centreline

PC

If you look at the OMDB ADR chart I would guess that it is similar to your situation. [ Runway 12R OMDB] (Note I am not familiar with Dubai just studying the chart).
They would appear to have a small strip of sand separating the taxiway and the start of the associated runway hard surface.:O

You could add a note in the AIP and maybe the local operators would benefit from a bit of extra information when you implement.

Also procedures should cover what happens when the opposite direction is in use - if the declared distances include that part of the taxiway as a Stopway/Clearway/RESA.

If it was unacceptable to still call it a runway between the taxiway and the displaced threshold then the starter extension option could get around the loss of TODA that would happen if you removed the runway before the threshold. Although this adds to the work required.

If the 8168 figures are OK there is probably a solution. It might even be very simple.

At DXB L4 is the taxiway west of 12R which is predominanty a departure rwy. A better example to look at at DXB is Twy R which is to the east of 30R, anything using that Twy has to be clear of the LSA before an inbound gets to 7dme.

Vehicles lower than 2.7m IIRC can use TWY R @ DXB with no restrictions with tfc on final to RWY30R. Anything bigger must be clear of OFZ by the time arriving acft reaches 2nm final.
Arrivals to RWY12R doesn't impose restrictions on the use of TWY L4, it does look a bit tight though and I try to avoid putting aircraft there simultaneously.
Deps off RWY30L is a different case as they might use the full RWY and min climb gradient is less than 3 degrees. No aircraft allowed on L3/L4.

Some time ago while taxying on B-East at EDDF/FRA I often received instruction to stop at B-East-3 and when landing traffic passed we could continue.
According to Jeppesen:
1.4. TAXI PROCEDURES
1.4.1. GENERAL
Taxiing on TWY B EAST permitted to ACFT with a size up to A321 (tail unit height
MAX 39'/11.8m) regardless of approaches to RWY 25L/R.
To avoid crossing the apch ground lines 25L/R while another ACFT is flying over
TWY B EAST, pilots can choose taxiing speed at their own discretion, or can wait at
the appropriate stop point (295'/90m in front of apch ground line on TWY B EAST).
Pilots can continue to taxi w/o a renewed clearance from ATC.
Today the taxiways east of 25C/L are marked as T and U and I am not sure what the concerning regulations are.

Taxying for a 07R departure from northside terminals at Barcelona you taxy right behind the 07L threshold and 25R localiser.

But you do not cross the paved surface of 07L. The threshold is displaced a considerable distance which would allow landing over taxying aircraft. Not what the OP is suggesting.

Here at CYYZ landing on 33L is permitted while taxying on D to 06L and landing on 33R is permitted when there are vehicles (usually snow removal vehicles, but not aircraft) on 06L. Taxying aircraft are held clear of the 33R approach and must be clear of the area by the time landing traffic is 1nm from touchdown. Not discretionary like in the Frankfurt example above.

http://i39.photobucket.com/albums/e1...psohednilt.jpg

It seems to me that is the wrong question to ask. The right question would be; is there either a runway hold or an approach hold on the taxiway?