Extending runway - stopway allowed?

[akerosid]

As you may know, DUB has a runway of 8,650', which is considerably less than the required length for a 340/777 at MTOW, particularly in Summer. I was just wondering how an extension to a more reasonable length could be brought about at a reasonable cost. Could an extension, say at the 10 end, be a stopway, assuming most departures are on 28? How has this been achieved at other airports? Can stopways be used as part of T/O distance and is there a problem with them supporting an MTOW aircraft?

[sky9]

Stopways can form part of the Accelerate Stop Distance. The Take Off Distance Available (TODA)is the TORA plus stopway. Any Takeoff performace is a balance between all three and any obstacles in the take off path. The easliest way is to get a computer analysis of the aircraft and play around with the various criteria.

At Manchester many years ago they extended the Runway length and it didn't make any difference to the performance of a 737 because they were limited by the obstacles. Removing a "few" trees improved the Take off performace to max RTOW.

[mustafagander]

Sky9

I don't think that's quite correct.

There have been a few threads broadly covering this topic.

To recap:-

Take Off Run Available (TORA) is the actual physical length of the useable runway.

Accelerate-Stop Distance Available (ASDA) is the TORA plus stopway.

Stopway is a surface on which the a/c can be stopped after an RTO. The surface may be damaged by the weight of the a/c.

Take Off Distance Available (TODA) is the TORA plus clearway.

Clearway is an obtacle free surface over which the a/c can fly while achieving screen height. Stopway is clearway. Water beyond the end of the runway can be used as clearway. There are certification limits on how much length of clearway can be used.

akerosid,

The short answer is yes, it could be quite cost effective as it's not full load bearing pavement required for stopway.

[mutt]

akerosid

In the case of Dublin, extending the stopway to the full length of the clearway will increase the takeoff weight by around 10,000 kgs, but it will still be less than the structural TOW of a 777-200 with GE90-90B's. To get the structural TOW, they will need a couple of hundred feet of tarmac.

Cheers.

Mutt

[4g_handicap]

mustafagander,

Everything you said was quite correct except 1 small point - I don't agree that stopway is clearway.

In rare cases it is possible that the stopway can exceed the clearway, as the stopway is limited by the first non-frangible obstacle exceeding 0.9m in height above the c/w surface.

I don't wish to dispute what you said, as you look like you know what you are talking about, but I thought I would bring the point up as I have been wondering about it.

Anyway, a good book is "Aircraft Performance Theory for Pilots" by PJ Swatton ISBN 0-632-05569-3


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[john_tullamarine]

Main point to make is that, for the conventional AFM (with data to permit unbalancing), any runway redesign for a critical aircraft needs to be looked at in some detail so that one doesn't increase a non-limiting parameter at great expense for little or no gain ... such as instanced above.

Then again, sometimes the operator misses the point anyway. I once did a safety audit on a particular operation and found that the RTOW data for one particular runway was scheduled significantly overweight .. the operator had done the sums on the basis of ASD .. but the limiting case (by a significant margin) was TOD1.

Good to see that Mutt survived Dallas .... best wishes for the Season, my friend ...

[ 02 January 2002: Message edited by: john_tullamarine ]</p>

[mustafagander]

4g,

Quite right.

I was trying to keep it simple and not introduce too many complications.

An airport that immediately springs to my mind is Camden, a GA field south of SYD. Rwy 06 has TODA much less than TORA because of obstacles. LDA 24 is, of course, reduced as well. So, here stopway is NOT clearway and unbalancing the field can yield performance benefits.

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