Wet Runway Performance

[xdc9er]

If the aircraft manufacturer has not published wet/contaminated runway charts /tables/guidance, can an aircraft legally be operated in a commercial operation (wet/contam. runway)?
Links would be appreciated,
type: DHC6 if your really interested!
X

[oldebloke]

The builder generally puts in some info under 'amplified'procedures if not in the 'perf' section..DH should have the info there as Canada 'certifies' to the JAA/EASA standard..:ok:
If not, ask DH if they have any 'new' info re' wet ops:*

[oldebloke]

Normally there will be 'contaminated' (slush) info in the perf' tables..Not necessarily 'WET' info though!!:(

[Old Smokey]

Good points made by oldebloke. To add to his remarks, beware of AFM "Advisory" data. The data may be correct or supplied for your good interpretation and decision making, but as "Advisory" data are not officially certified. From the legal point of view, operating at the most limiting of the "Official" or "Advisory" data would be common-sense, legal, and (probably) safe.

Regards,

Old Smokey

[fly.net]

Can anyone please advise me on the Contaminated Runway Takeoff Perfo B737 : in fact, when do I use table [Wet Runway], when [Slush/Standing Water] and when [Slippery Runway]...?


Example 1 :Weather report is 2 mm standing water
Do I use [wet runway] or [Slush/Standing Water] ?

Example 2 :Weather report is 10 mm dry snow
Do I use [slippery runway] or do I enter [Slush/Standing Water] with the equivalent of 2 mm wet snow ?

Example 3 :Weather report is 4 mm ice
Do I use [slippery runway] (but I have no breaking action) or do I enter [Slush/Standing Water] with the equivalent of 33 mm snow ?


Example 4 :Weather report is 20 mm wet snow - braking action poor
Do I use [slippery runway] (braking action poor) or do I enter [Slush/Standing Water] with 20 mm wet snow ?


Thanks for your help, this is really a grey zone for me and I can't find any reasonable explication in the flight manuals.

[Sir George Cayley]

No friction cart is capable of producing coefficient of friction readings for anything more than 3mm of wet water. ie not slush.

Compact snow and ice can be measured and tables are available.

If the runway under normal dry conditions meets or exceeds the minimum friction value ( and therefore is not NOTAM'd likely to be slippery when wet)
then so long as there is blacktop and 3mm of wet water or less than braking action is "good"

If there is slush, wet snow, or more than 3mm of water then then braking action will not be good. The best you should hope for is an estimate from the preceeding a/c and hope it wasn't a Piper Cub or get the Ops guy out of his cosy warm office for a braking test in his 4 x 4. Again only an estimate,

Or, here's a radical notion - divert?


Sir George Cayley

[oldebloke]

AS sir george says up to 3mm of water is WET,once you get more you have to look at Contaminated (flood/slush)conditions(A real drag on perf')
Be very careful with SLIPPERY conditions as no authority recognizes these facts for Certification.The crosswind charts for the lowest friction allows one a crosswind of 5knots,and nobody knows the stopping distances.ONe shouldn't be out on a slippery day...If one is on final to a runway reported as POOR braking,you can only enquire as to where the preceding aircraft stopped,or did he go off the end??...Messing around on slippery runways/taxiways ,your on your own!!
I'm surprised there's info in the book referring to 'slippery'.....:*

[Bigmosquito]

JAA says that a runway is contaminated when more than 25% of the runway surface area (whether isolated areas or not) within the required length and width being used is covered by the following:
- Surface water more than 3mm (0.125 in) deep, or by slush or loose snow, equivalent to more than 3mm (0.125 in) of water;
- Snow which has been compressed into a solid mass which resists further compression and will hold together or break into lumps if picked up (compacted snow); or,
- Ice, including wet ice.
The US FAA says that a runway is considered contaminated whenever standing water, ice, snow, slush, frost in any form, heavy rubber, or other substances are present.
Manufacturers are usually publishing a surface contamination in terms of equivalent water depth.
Airport operations on loose snow and slush covered runways are treated in a similar manner as operations on a runway contaminated with standing water.
Have a good one.

[fly.net]

Thank you for the general info, which I was partially aware of.

Still looking for the answer to my question ; which table do I use in the QRH B737 ??

[oldebloke]

for example (1) use WET
(2) use 2mm slush
(3)no ops on ICE
(4) use 22mm slush
As I see it
Cheers:ok:

[Bigmosquito]

I don't know about the B-737. However airports operations on loose snow and slush covered runways are treated in a similar manner as operations on a runway contaminated with standing water. The only difference is that because of different densities, a measurable depth of loose snow or slush must first be converted to an equivalent depth of standing water.
Do you have a table converting loose snow, slush into water depth?
Other type of contamination are treated with other tables.
Up to 3mm of water - WET (JAA)
Above 3mm of water & more than 25% - Contaminated (JAA)
Example:
35mm (1.38 in) of loose snow is equivalent to 12.2mm (0.48 in) of standing water.
You have then a runway surface contaminant in terms of equivalent water depth.
This number is then entered into the appropriate charts.
But before going further, what type of charts does Boeing provides?
Rgds.