Topic Author
Posts: 31
Joined: Sat Mar 20, 2004 9:44 am

Takeoff Distance With Double-Displaced Thresholds

Thu Oct 14, 2004 3:31 am

Having read through a number of previous topics covering diplaced thresholds, I have a question about an issue that remains unclear to me...

My question: When taking off on a runway with displaced thresholds on both ends, is the runway length beyond the displaced threshold at the far end of the runway usable when calculating the Take-Off Run Available (TORA) or can it only be used to calculate the Accelerate-Stop Distance available (ASDA)?

Here's what prompts my question:

Here at MSP we have one runway - 4/22 - that has displaced thresholds at both ends. In this picture, you are looking right down the length of Runway 4 (View Large to be able to see the markings for the displaced thresholds):

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Photo © Rick Resnik

The MSP airport diagram indicates that runway 4/22 is 11,006 feet long and that, when landing (due to the displaced thresholds) Rwy 22 has 10,018 feet available and Rwy 4 has 9,456 feet available. Here's the chart:

I believe (but am not sure) that the reason for the displaced thresholds on 4/22 at MSP is noise abatement (keep approaching aircraft higher over residential areas) and NOT because of physical obstructions beyond the ends of this runway.

Rwy 4/22 is usually used just once a day (except in rare wind conditions when the 12s or 30s can't be used) by NW flight 19 taking off for NRT . (And even this flight can use 12R/30L when the winds, temperature and load allow it). When flight 19 calls up ground control to request its push-back from the gate, the pilot will typically say something like: "We're going to need Runway 22 full length today." So, I also wonder if that "full length" request has anything to do with being able to use runway length beyond the far end's displaced threshold for the takeoff run.



MSP - where the DC 9s and DC 10s make their last stand
Posts: 564
Joined: Sat Mar 11, 2000 12:33 pm

RE: Takeoff Distance With Double-Displaced Thresholds

Thu Oct 14, 2004 4:54 am

Displaced thresholds do not ordinarily affect takeoff distance. At my local airport (Albany, NY/KALB) RWY 10-28 is 7200 feet with a 1200 foot threshold on the 28 approach end. 6000 feet are available for landing, 7200 for take off.
Posts: 924
Joined: Sat Jan 01, 2000 11:45 am

RE: Takeoff Distance With Double-Displaced Thresholds

Thu Oct 14, 2004 5:36 am

I believe that the whole length is available for takeoff, regardless of where the displaced threshold(s) is. The displaced threshold is simply there to tell pilots what part of the runway to land on.

About the 747 out of MSP: I don't know why the pilot would need to request anything less than full length, because if they are going to need more than 12R, they are most certainly going to need all of 22.

Twin Cessna 812 Victor, Minneapolis Center, we observe your operation in the immediate vicinity of extreme precipitation

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