View Full Version : LHR "grooved" Runway?!


flymeboy
9th Jan 2006, 15:44
Hello everyone,

I just wanted to find out if LHR has grooved runways? This came about as LHR never says that it has a "wet" runway on the ATIS. The only way that this could possibly be is if the runways were grooved (in which case they are technically dry for a/c performance).

In our airline I am quite often critisised for briefing to use dry performance figures out of LHR and am told to use wet (eg if the ground is wet) - even though the runway is grooved! What do others do?

Any ideas?!



BLK 33
9th Jan 2006, 15:54
Yes, they're both grooved from the last re-surfacing (2000/2001 AFAIK), prior to which they had been surfaced with a Porous Friction Course.
:ok:

stue
9th Jan 2006, 16:16
Does it not rain at LHR? perhaps it only rains up-north?:p

Jetstream Rider
9th Jan 2006, 16:32
Quite often at LHR when the weather is "wet" the runway is visibly dry. I have taxied out on wet taxiways a number of times to find a dry runway. This might also be a function of the number of movements as well as the surface. I still use wet take off performance when we request the figures - although in practice it makes no difference unless a reverser is locked out or the runway is short - at least for us.

Red Four
9th Jan 2006, 22:38
If you have PFC can you then groove the runway, or does it need to be re-surfaced in something else before/whilst grooving?:confused:

pushapproved
9th Jan 2006, 22:48
At Gatwick the Runway is grooved and "wet" does get broadcast on the ATIS when appropriate!

issi noho
9th Jan 2006, 23:43
answer depends on the authority responsible for your airline. As far as i'm aware the uk caa dont permit the use of dry performance on a wet runway for either grooved or pfc, although your company can apply for a deviance from the regulation for specific reasons. irish authorities do allow it on grooved surfaces and there is mention of it in jar ops if i search hard. why bother though use wet perf coz your company will only try to force you into short strips in the wet if they think your game for it.

TheOddOne
10th Jan 2006, 00:34
If you have PFC can you then groove the runway, or does it need to be re-surfaced in something else before/whilst grooving?:confused:

No, I don't think you can. I think if you tried to cut grooves in PFC you'd break the surface up. Anyway, the grooves would probably stop the PFC doing its job as designed.

Having worked with both surfaces over the years, in the long term I think that the better surface is the grooved Marshall asphalt. PFC works well when new, but does tend to break up badly in later life, causing operational problems as well as maintenance issues. It does of course get clogged up with rubber, as do the grooves, but grooves can be cleaned out. Also, PFC is a bit of a nightmare in the Winter. Potentially, if you get moisture in the pores and it freezes, it will blow the surface, whereas ice in grooves not only doesn't damage the surface, it doesn't reduce the friction much, either!

It's standard procedure to lay the Marshall asphalt first, leave it for a few days to 'go off', then cut the grooves. The problem with this is you have a potentially slippery surface if it rains before the grooves get cut. Asphalt is notorious for 'sweating' oils through the surface when it's newly laid.

Cheers,

The Odd One

Red Four
10th Jan 2006, 20:59
Thanks Odd One,

Useful information.


4

KLMer
18th Jan 2006, 18:00
AMS is the same never gives r/w state on the atis due groves. but we still have wet tables SCD..