LHR runways - Slippery when wet?
 

Yesterday LHR ATIS was giving runways reported as slippery when wet? Just wondered what the story is on this, can we expect this on a regular basis? I know that there is wip on 27R but it seemed to apply to 27L as well.

Sooner or later this will cause havoc.
757/767 crosswind limit for take off and landing is just 10kts, and I expect that other types are similar.
Last winter someone happened to mention that 27L was a bit slippery as they turned off, and this meant that noone would land on it. ATC refused to do a mu meter test on it as it would close the runway for 10 minutes, but as it turned out it was effectively closed for hours, with only 23 available for landing.
It's only a matter of time before this chaos happens again. (just a bit of rain and a wind of 200/15 for example).

I tried to chase this up yesterday when I was on arrivals. On handover I was given both 27R and 27L are slippery when wet, but after a conversation with The Aerodrome safety unit, they said it applied to 27L only, apparently due to tyre build up at the midpoint.

Snooky, I cannot believe that we (ATC) would refuse a grip test. All we can do is request the Aerodrome Authority carry out a grip test. We have no authority to say yes or no.

Gonzo.

I also do not believe that ATC refused a grip test. As Gonzo states, the mid portion of 27L has been contaminated by rubber deposits and in wet conditions the braking coefficient ranges from 0.33 to 0.54. This equates to medium braking action. Instead of a vague "slippery when wet," which I believe leads to some airlines using performance calculations for icy runways, the Airport Authority should measure the exact braking action with a grip tester and publish this information, even if it results in a loss of a runway for 15 minutes.

Snooky, please clarify the crosswind limitations for B757/B767 aircraft - under what conditions does the 10kt limit apply?

Hopefully all will be resolved when they resurface 09R/27L next year!

Yes, my company requires that we treat a runway which is "slippery when wet" as an icy runway and this effectively prohibits take-off from that runway as long as it is wet! When the actual braking coefficient readings for the runway were requested we were told that they could not be passed and that "slippery when wet" was all we could work with!

When LGW resurfaced the main last year, this same debacle dragged on for a number of weeks. It wasn't long before NATS & BAA became quite well informed of every airlines SOP's and eventually found a solution.

I recall the turning point was when a B744 tried to turn off and just kept on slidin'!!

Perhaps BAA LL & ATC ops should give Sussex Regional a call.

As far as grip tester runs went, BAA refused several requests, and even when they did do them, the equipments calibration wasn't exact enough to pass to pilots?!!

Ta ta,
PA

I accept that it's not an ATC decision whether or not to carry out a grip test. However on the occasion that I described, when a grip test was requested it was immediately refused (no consultation time).
The problem is one of terminology.

A slippery runway is defined as having a uniform theoretical braking coefficient of 0.05Mu over 100kts and 0.08Mu below 100kts.
If a runway is promulgated as liable to be slippery when wet this means that a portion of the runway (over 100m) has a Mu meter reading of 0.39 or below (as seems to be the case for 27L).

To just say that a runway is slippery when wet will cause most pilots in these litigeous days to take the worst case and use the slippery runway figures, resulting in the 10 knot crosswind limitation. This is why it is vital to have Mu figures available and to be precise when describing a runway as slippery.

This is going to get interesting. Thanks to the total lack of FAA regulations for contaminated runways, you are going to end up in a situation where US carriers and a certain ME carrier will be quite happy operating off the "slippery when wet" runway, but the JAR operators wont be allowed!

You better get that friction tester out :)

With the "Advisory Data" available to FAA operators, a wet/slippery runway will result in a v-speed decrement and possibly a weight decrement (Depending on the number of engines), but a ICY runway usually prohibits takeoff.


Mutt.

[ 05 October 2001: Message edited by: mutt ]

Snooky's response is clearly knowledgeable but I'm not sure how universal his comments are.

In the UK, although it's hard to find, the rules are that runways have to be notified (by which I presume that means NOTAM'd or in the AIP) as 'liable to to be slippery
when wet' when routine testing shows that friction level has fallen below a specific level. The actual value varies depending on the friction testing equipment used and the values reported by the equipment also vary with other factors such as speed so I don't think the numbers produced are absolute but rather useful relative data generated under closely controlled conditions.

As I recall, ATC are not allowed to pass mu-meter readings from wet or slushy runways (instead we give surface conditions and braking action reported by pilots) - presumably because of the differing numbers that friction testing equipment comes up with in those conditions.

The above comes from an information notice issued to airport operators by the CAA and (the ATC bit) from what I remember from winter ops. It may be different outside the UK.

take ECAM action's original post said the the runway was reported as 'slippery when wet' - unless this was actually passed/broadcast as 'liable to be slippery etc' it seems to me that the statement is incredibly confusing and misleading.

In some areas, our lives are ruled by lawyers. Nothing much wrong with that, as it leads to lower insurance premiums (in nett terms) and an occasionally-ultra-conservative operation.

However, runway state, braking action, contaminants, and so on, all need a good hard look.

In particular, the performance requirements on 'slippery when wet' runways, and the situation regarding braking action reports on snowy runways, are cases in point.

We suffer, in the UK, from having relatively good weather most of the time. When the snow hits, it takes us by surprise, but it's soon gone again. If we had bad snow all the time, we would have resolved these issues.

Maentime, Boeing operators (in particular) will suffer badly if LHR gives 'Slippery when wet', and I, for one, am not sure who will address these issues.....

Hi everyone!Ive been reading some of the messages here and have noticed that some of you are actual controllers at Heathrow. Ive always been interested in atc. It is my second chioice, after a pilot. I was just wondering what is the best way into atc(+the pay?!).Also, do you need any specific A-levels, degrees??oh yeah was obn the luxair lg403 flight earlier in the year!!thanks a lot.

Good to know that some are still interested in the profession!

Rather than repeat all of which has been said many times, just search back over the past 2-3 months worth of threads. There is a myriad of information there!! Everything is there from recruitment/pay etc and contact numbers!!

Good luck!

[ 11 October 2001: Message edited by: Bright-Ling ]