The wet runway dilemma..
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The wet runway dilemma..
There seems to be a difference in the definition of a wet runway between ATC and Jaa ops.
The JAA defines a runway as wet when it has a "reflective surface" and as such this is the definition used when calculating aircraft takeoff and landing performance. The tricky situation arises when the tower calls the runway 'wet', when it appears 'damp', although by jaa ops definition it can still be concidered dry as far as aircraft performance is concerned, especially on a grooved runway. I agree this is erring on the safe side but, it is also important to get the job done where it is safe to do so. This situation can put the pilot in the difficult position of having to asses the runway state when ATC calls the runway wet, to try and determine whether or not it is wet under the JAA definition or not. On a short runway this is can be critical. On the basis that the aircraft may well be IMC until quite close to the runway the pilot is probably not in the best position to make that call!
I have tried doing a search on this subject and did not come up with much. Appologies if this has been previosly covered.
The JAA defines a runway as wet when it has a "reflective surface" and as such this is the definition used when calculating aircraft takeoff and landing performance. The tricky situation arises when the tower calls the runway 'wet', when it appears 'damp', although by jaa ops definition it can still be concidered dry as far as aircraft performance is concerned, especially on a grooved runway. I agree this is erring on the safe side but, it is also important to get the job done where it is safe to do so. This situation can put the pilot in the difficult position of having to asses the runway state when ATC calls the runway wet, to try and determine whether or not it is wet under the JAA definition or not. On a short runway this is can be critical. On the basis that the aircraft may well be IMC until quite close to the runway the pilot is probably not in the best position to make that call!
I have tried doing a search on this subject and did not come up with much. Appologies if this has been previosly covered.
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The reporting in the UK of runway states on the atis came about as a result of an incident at Southampton in Oct 98 (see http://www.aaib.dft.gov.uk/bulletin/jun00/gukfn.htm ).
While I realise that there is a difference in reporting criteria, it would take a braver man than me to decide that the runway is dry when ATC are reporting it as wet. Think of the concequences if you should go off the end (insurance/career etc).
While I realise that there is a difference in reporting criteria, it would take a braver man than me to decide that the runway is dry when ATC are reporting it as wet. Think of the concequences if you should go off the end (insurance/career etc).
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Interesting report. Out of interest, does anyone know why many uk airfields report rwy state on the ATIS, but LHR does not. Especially as 27L was notamed as being slippery when wet for several months, you didn't always know if the runway was wet or not on landing.
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On the subject of wet runways we can take it one stage further and talk about snow covered runways (winter is coming ). As a recent article in CHIRP illustrated ( it was just undernath the one about low cost carriers that caused all the furore ).
In some ways the situation is reversed in that, if I, as a controller have been given braking action figures from a runway inspection vehicle in conditions of wet snow ( we don't get anything else ), that indicate the runway braking action is extremely poor, I am not allowed to pass this information to aircraft. We used to be allowed to pass these figures as long as we added the suffix that they were unreliable.
So we are left in the situation as controllers in a fairly wintery outpost that if we suspect that the next landing 757 may go sailing off the end of the short runway, that we try and drop hints or desperatly search for other reports to put pilots off attempting landing. I am even awre of a colleague who contrived to send a landing medium sized jet, on short final, around so the flight crew could get a close view of the runway surface. The aircraft elected to divert.
I am aware that these problems are due to liability issues with mu-meters, BAA and so on. I am also aware that it has been raised at the UK flight safety committee. However so far nothing has been done.
...and winter is almost here...
In some ways the situation is reversed in that, if I, as a controller have been given braking action figures from a runway inspection vehicle in conditions of wet snow ( we don't get anything else ), that indicate the runway braking action is extremely poor, I am not allowed to pass this information to aircraft. We used to be allowed to pass these figures as long as we added the suffix that they were unreliable.
So we are left in the situation as controllers in a fairly wintery outpost that if we suspect that the next landing 757 may go sailing off the end of the short runway, that we try and drop hints or desperatly search for other reports to put pilots off attempting landing. I am even awre of a colleague who contrived to send a landing medium sized jet, on short final, around so the flight crew could get a close view of the runway surface. The aircraft elected to divert.
I am aware that these problems are due to liability issues with mu-meters, BAA and so on. I am also aware that it has been raised at the UK flight safety committee. However so far nothing has been done.
...and winter is almost here...
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I find it quite fascinating how doubts arise over certain procedures/ equipment which have been in use for years.. Why is this situation now arousing such interest and how have pilots coped for the last 50 years?
When I worked in the tower at Heathrow and was asked for the runway state I'd simply look out of the window and say "it's a bit damp", or "it's very wet". Nobody ever queried those remarks... and nobody ever ran of the end of the runway!
When I worked in the tower at Heathrow and was asked for the runway state I'd simply look out of the window and say "it's a bit damp", or "it's very wet". Nobody ever queried those remarks... and nobody ever ran of the end of the runway!
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Eddyboog,
Easy answer is to get Ops 1 to do an inspection and accidentally on purpose slide off the side. You can then tell us that you have no BA figures but that the fire service are currently trying to recover the landrover!
Easy answer is to get Ops 1 to do an inspection and accidentally on purpose slide off the side. You can then tell us that you have no BA figures but that the fire service are currently trying to recover the landrover!
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why do aircrew still ask for B/A figures on a wet runway?
we have been told not to give them because they are unreliable, yet some crew still insist they need them before making an approach-is this another mismatch between mats1 and ops manuals?
as the previous post said the whole slush/wet snow/ice nightmare is almost upon us again-trying to guess whether you can give out the figures or not, what the contaminant really is-at least we can go out ourselves and have a look, not a practice available to many nats controllers I guess. In fact we have found that often the best way of discovering what aircrew can/cannot accept is to take them out on the inspection and see for them selves(not a lot of help for arrivals!)
we have been told not to give them because they are unreliable, yet some crew still insist they need them before making an approach-is this another mismatch between mats1 and ops manuals?
as the previous post said the whole slush/wet snow/ice nightmare is almost upon us again-trying to guess whether you can give out the figures or not, what the contaminant really is-at least we can go out ourselves and have a look, not a practice available to many nats controllers I guess. In fact we have found that often the best way of discovering what aircrew can/cannot accept is to take them out on the inspection and see for them selves(not a lot of help for arrivals!)
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icy runways
we used to get a problem in the raf with aircrew not beliving the runway condition. i heard about a wing commander at church fenton who didnt believe that the runway was icy, he went out in his issue mini to inspect the runway. youve guessed it, no he didnt crash but when he got out of the car on the runway he went over on his backside!
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Eddybog,
Don't you guys use TAPLEY or MU readings that you get from the airport vechicle and then pass these readings onto the pilot, as well as Field conditions.
For Example: we will put on the atis, Runway 23, Snow covered 1 inch packed snow and Ice, MU of 30 35 40.
The pilot is supposed to have the MU breakdowns for their particular aircraft and be able to determine if breaking is NIL, POOR, FAIR, or GOOD.
As for wet runways, if a pilot ask if a runway is wet I'll either say it appears to be wet or the runway appears dry.
Mike
Don't you guys use TAPLEY or MU readings that you get from the airport vechicle and then pass these readings onto the pilot, as well as Field conditions.
For Example: we will put on the atis, Runway 23, Snow covered 1 inch packed snow and Ice, MU of 30 35 40.
The pilot is supposed to have the MU breakdowns for their particular aircraft and be able to determine if breaking is NIL, POOR, FAIR, or GOOD.
As for wet runways, if a pilot ask if a runway is wet I'll either say it appears to be wet or the runway appears dry.
Mike
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The old system of providing braking action reports based on Mu readings although fallible (and yes there are incidents and accidents to pove it), is infinitely preferable to having very little, or worse no information at all. That might explain why crews are still asking for B/A reports. I cannot see how this problem can be addressed until the prickly issue of liabilty is resolved, and protection in place for those who provide the information. Particularly in the case of Mu readings, this is factual information. Slightly simplistic I know as braking action can be patchy, but still better that the system we have now.
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interesting thread..
In the Lr60, we suffer a huge penalty when landing in the wet. By "wet" I mean shiney surface, and this is a huge problem when landing somewhere like EGLF. We can land at MLM in the dry but when its called wet, we can't land unless we have zero fuel(obviously not an option.) Also what irks me is that EGLF have just redone their runway, but it is not Grooved!! stupid..
Hence we have stopped ops into eglf due to the chance of having to divert due to wet rwy, and this annoys the pax (and sticks them onto the M25 to get from eg EGGW to EGLF..)
My plea is that when issuing rwy conditions, be a bit more picky about whats damp and whats wet..
In the Lr60, we suffer a huge penalty when landing in the wet. By "wet" I mean shiney surface, and this is a huge problem when landing somewhere like EGLF. We can land at MLM in the dry but when its called wet, we can't land unless we have zero fuel(obviously not an option.) Also what irks me is that EGLF have just redone their runway, but it is not Grooved!! stupid..
Hence we have stopped ops into eglf due to the chance of having to divert due to wet rwy, and this annoys the pax (and sticks them onto the M25 to get from eg EGGW to EGLF..)
My plea is that when issuing rwy conditions, be a bit more picky about whats damp and whats wet..
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lr
trouble with the description of runway conditions is that of course it can be very subjective-we use both ops people and the firemen for inspections, and to be honest the runway state can differ just depending on who is out there-and yes its worse case when trying to decide between damp and wet-we have more discussions about this perhaps than about whether its moderate or heavy rain! my guess is that we probably do overstate the amount of contamination, but thats just human nature I suppose
trouble with the description of runway conditions is that of course it can be very subjective-we use both ops people and the firemen for inspections, and to be honest the runway state can differ just depending on who is out there-and yes its worse case when trying to decide between damp and wet-we have more discussions about this perhaps than about whether its moderate or heavy rain! my guess is that we probably do overstate the amount of contamination, but thats just human nature I suppose
