Displaced Threshold

[Olendirk]

Guys,

scenario: beatiful day, CAVOK. clearance for a visual approach. runway has a displaced threshold.

Can we land on the displaced threshold? Or not? What are the differences, because doing a takeoff on it is ok.

Thanks


OD

[john_tullamarine]

Considerations ..

(a) normally, the displaced threshold indicates the existance of an approach obstacle requiring the displacement to achieve the required minimum obstacle clear gradient to the threshold. ie the approach slope is slid along the runway until it sits appropriately with respect to the obstacle .. et, voila ... the displaced threshold is at the other end ...

(b) landing short exposes the operation to a higher than standard approach slope or reduced clearance from the critical obstacle. I can see a difficulty arguing the matter at the enquiry if there is a mishap

[TWApilot]

Exactly....

It may be displaced due to an approach path obstacle. You still must aim for a spot 1,000 feet down from the displaced threshhold, to insure obstacle clearance.

[con-pilot]

However, that is not always true. Some airports, Long Beach and Orange County come to mind, the displaced threshold is due to noise abatement. Never the less, as far as I know you cannot land on a displaced threshold.

In case of Long Beach if you drop below the glide slope (VFR day of course) in a large aircraft you are guaranteed to get a letter from the airport manger's office. Want a copy of mine? :uhoh:

Now San Diego is a perfect example of a displaced threshold due to obstacles.

[avionneta]

displaced threshold has to be considered as the beginning of the runway. before, you're in the grass (even out of concrete in that case)

[Finals19]

A displaced threshold can therefore be included in LDA, if it is at the far end of the landing runway? (i.e. it can be used for roll out?)

[Roadtrip]

Another reason for a displaced threshold is that the surface may not be stressed for continuous landings.

In the U.S. it is not permissible to land on a displaced threshold, however, when doing a little research it appears that it is permissible in Canada if the pilot can ensure obstacle clearance on approach. I didn't know that. Maybe some of our Canadian pilots can confirm, deny, or clarify. Here's my source:

AGA - 3.0 RUNWAY CHARACTERISTICS (http://www.tc.gc.ca/CivilAviation/publications/tp14371/AGA/3-0.htm)

[Doors to Automatic]

Looks like it is allowed in the US: :ok:

YouTube - Hard Landing: Returning home from Paris, France 1999 (http://www.youtube.com/watch?v=OGbBYOAUKRk)

[xkoote]

Where we fly, you are allowed to drop below to make a landing before the displaced threshold granted you are under visual conditions and you can assure terrain clearance. Under IMC conditions, approaches require a minimum vertical and lateral (if I'm not mistaken) terrain clearance for obvious reasons. But if you are completely VMC and able to maintain your own clearance with terrain there shouldn't be a problem. Makes sense, otherwise all runways should have displaced thresholds because you'll get too close to the ground before you reach the runway for the landing.

[john_tullamarine]

A displaced threshold can therefore be included in LDA, if it is at the far end of the landing runway? (i.e. it can be used for roll out?)

Maybe yes .. maybe no ... depending on the airport declared distances. ie is it not up to the pilot to make such assessments in normal operations .. the runway will have a set of declared distance data .. including LDA (which should be measured from the other end threshold.

[OverRun]

Maybe is the best description. And the airport declared distances is the best rule to use.

I just scanned through the Australian declared distances (ERSA) out of interest, and generally the runway before the displaced threshold has been included in the LDA for the other direction. However I also found several runways where it wasn’t; two of which I built. While I know why one is so, I can’t remember why the other. So if the builder isn’t sure, it would be a bold pilot indeed who decides that he knows distances better than the published figures.