WET WET WET reported on ATIS but RWY not wet?
 

Hi all,

I have a question concerning the announcement of a WET Runway on ATIS or by ATC while approaching UK airports.

Recently we had a flight into Northolt UK and the ATIS reported the Runway as WET WET WET. The weather was fine in the whole London Area with scattered clouds and sunshine. I understand that before our arrival they had rain showers.

Since the runway is quite short and commercial ops requires factorisation of LDR + wet factor the landing performance on the given day with the wet factor added was only legal by a few feet. After landing we noticed that the runway was almost dry again.

After hanging around for almost 5 hours we departed again. No rain for the rest of the day and a completely dry RWY.
ATIS reported WET WET WET again.

I would like to ask the following questions and would be happy to hear your opinions:

1) Is it legal to "assume" a certain runway condition as dry or damp if you are sure - even if the reported RWY condition is WET?

2) Is there any particular reason why UK ATC reports RWY as WET even with light rain and/or no visible rain around the airport. Never heard that in the rest of Europe unless there was heavy rain or reports of poor braking action or contamination.

Cheers!

Please provide a reference that states pilots can substitute a pilot's assessment of the runway state.

Request a runway inspection if you suspect the runway is damp.

Just a thought but I have certain found that things are still broadcast on the ATIS which were only current hours ago.

I departed a UK airport where the ATIS warned of a marked temperature inversion at 1,000 ft. When we departed I observed no inversion and commented to ATC before switching to departure freq. "Ah yes that was reported several hours ago.....we'll have it taken off the ATIS" was the response from ATC.

Why "WET WET WET" when a simple WET will do just fine!

GF

Because it is reported for each third of the runway in sequence.

The reporting of runway state on the ATIS in the UK was brought in after an incident in Southampton in 1998.

https://www.gov.uk/aaib-reports/fokk...4-october-1998 gives the full story but basically the crew were not warned of the runway state and subsequent calculations showed that the aircraft was never going to stop in the available distance with the normal technique.

I thought it was because the runway was very wet :)

I think this comes down to communication between ATC and the aircrew.

Nothing prevents a pilot from asking for an update, and by the same token for ATC to ask for a further runway inspection should circumstances change.

As for the inversion, should not the time of the report be included?

I would rather use wet speeds on a dry runway than have to explain why I used dry speeds when the ATIS said the runway was wet, in the event of any incident.

Using wet speeds "to cover yourself" on a dry or almost bone-dry runway is shooting yourself in the foot somewhat in the event of an engine failure.

Dry performance requires you to be at V2 at the 35ft screen height at the end of the TODA.

Wet performance only requires you to make a 15ft screen height at a speed that will allow you to each V2 by the time you reach 35ft some point in the future.

Our Ops Manual allows the PIC to elect to use dry speeds and limits on a damp grooved runway on his or her assessment of the conditions.

(1) No ‘assumption’ is legal; any notion of legality must be replaced by the goal of being safe. Thus the choice of action must be justifiable to you and the crew.
If the WET x 3 report is the best information available, then use it.

(2) If the runway is not dry then it is WET or worse. See the refs in http://www.pprune.org/9263410-post18.html AIC 86/2007

Actually, Wet Wet Wet is a group that did that song from Four Weddings and a Funeral.

Just by observation, it does appear UK airports report WET when it should be classed as DAMP quite often.

Hi everybody,

thanks for the many answers! Good to see many replys with very welcome thoughts regards to this topic.

I was not aware that there was an incident in the UK that resulted in the mentioning of RWY conditions on the ATIS. Very helpful information indeed.

Thanks:)

If apron appears dry and runway is advertised as wet,i will ask a confirmation.
If i land on a dry runway when advertised as wet i will definitively let them know that it is DRY DRY at least��
In any case i will
use perf based on advertised conditiins..part of covering my skinny a....

The reason is probably because the Met System/ATIS message has not had the runway state updated. Simple user error...

Yes, it is a British disease. Reporting a runway as wet when it is dry is as bad as reporting a runway as dry when it is wet. It may be perceived by someone as covering their backside by taking a 'worse case' position but all it really does is tell you that you are dealing with incompetence. And it should be treated as such. An Air Safety Report/MOR is appropriate in such cases; we should be able to rely on accurate and topical runway reports from ATC.

The interesting question is what values should we use for our performance? Fortunately our AOMs give little guidance. They merely imply you should use the appropriate values. Which is convenient because it means I (or even better, we) can decide for ourselves. So if a runway is plainly dry or damp, I'll use 'Dry' values. And as far as I am concerned, that is legal. The problem comes with 'Wet' and contaminated. The reason is that these are values are reported by unreliable and/or incompetent observers.

So do you go or not?

PM

I only fix/maintain the kit and my flying experience is not CAT or IFR so forgive my ignorance, but I thought that any runway state aside from DRY DRY DRY is regarded as "contaminated"? Correct me if I am mistaken?

TelsBoy

Let me ask you another question:

If the ATIS reports the runway dry (aka not being wet), and the rain starts to pour down. Do you use dry or wet figures for your calculations? :E


To return to your question. The ATIS is an observation at a specific time (in the past). Why would you get the idea (which document) that it legally binds you to using a specific choice of conditions for take off? It's just a source of information to take into account.

What legally matters is the actual condition of the runway:

Looking at EU-OPS 1.530 (CAT.POL.A.205 - or what ever they call it today) you are obligated to take account of: Nowhere does it mention which source should be used to get that information.

PM, ‘me thinks you assume too much.’

“… while approaching UK airport…” How can we visually differentiate between a dry tarmac runway and a damp ‘grey’ concrete runway, or even a tarmac runway with a slight change in colour = damp?

Jw, re engine failure, which might be better; a reduced screen height with a ‘go’ on a dry runway using wet performance, or a stop on a misjudged wet runway using dry performance.

Cosmo, ‘what legally matters’ is the judgement of the investigation after an event; there is no ‘legality’ beforehand, as the process depends on an adverse outcome. ;)

Using WET cautiously should not be considered as ‘foot shooting’ or ‘covering backsides, but that it could be the better judgement for a safe operation based on the information available.

ICAO circular 329 “damp runways effectively reduce aircraft braking action below that of a clean and dry runway.”

Draft ICAO Industry best practices manual for timely and accurate reporting of runway surface conditions by ats/ais to flight crew.
“Because the aviation community is heading towards a three-point scale for runway state (i.e., dry, wet, or contaminated), the need for a definition of damp can be questioned, as a damp runway would be considered to be wet. However, there are a number of performance standards and advisory circulars presently in force that would require a definition for damp. Consequently, a definition for damp is still believed to be required until consistency is achieved with respect to the associated performance standards.”

For performance standards; Damp=Wet.