Cessna, snow and Braking action less than good

[pilot dude]

Hi,

When flying cessna (560, 525) aircraft under JAR-OPS on snow covered runway with braking action less than good what tables do you use to calculate t/o distance? The one for snow covered runways in the EASA cert supplement does not tell for (or until) which braking action or Fc it is good for. But if not mentioned shouldn't we according to JAR-OPS assume it's to be used ony with B/A Good of Fc above 0.40?

Is this one of those JAR-OPS gray area.

[fjordviking]

If your a/c has the EASA supplement, you use that. Simply go into the tables with the current RWY conditions and get your numbers. Disregard braking action.

Best regards,

Fjordviking

[Tmbstory]

Pilot Dude:
I have not operated under JAR- OPS, but have operated under other Regulatory Authorities with a Cessna 650 in snow, slush and ice conditions.

The Cessna advice was to adjust the V1 by zero to +3 knots, multiply the Take-off distance by "Wet" by 1.3, "Water less than 0.4 inch" by 2.3, "Slush Less than 0.4 inch"by 2.3 and "Loose dry snow " unknown for take-off and Landing by 2.4.

Does this help with your query

Tmb

[pilot dude]

If your a/c has the EASA supplement, you use that. Simply go into the tables with the current RWY conditions and get your numbers. Disregard braking action.

But if there is no mention of for which braking action the snow covered rwy is applicable in theory you can use the same t/o distance for b/a poor then for medium to good. This sounds strange to me. required runway distance goes up as braking action goes down.

[fjordviking]

When it comes to operating on contaminated RWYs we all become test pilots as it`s impossible to give a correct Braking action and the authorities have gone away from braking action as a reliable tool. Better to stick with the performance numbers in your aircraft manual. Like it or not, it`s not an exact
science and never will be.

[Miles Magister]

I agree with the post above. If there is not clear information in your flight manual supplements the best table to use is the one you put your coffee on while you wait for better conditions.

MM

[pilot dude]

fjordviking, the problem for me is not so much to fly from runway's with braking action less than good, the problem for me is to do it legal. As far as i know you need to have demonstrated or calculated runway lengths dependant on braking action for taking off. if cessna says i need 9000 ft instead of 3000 ft on a snow covered runway, that is fine for me but i dont think it is legal this way (not acc to JAA anyway)

[Vee1Kut]

If not sure, you take the longest of the numbers, that's the safest thing to do....using the shortest of 'legal numbers' to keep legal, followed by an overrun at the end of runway, makes running the numbers kinda moot at that moot. Not everyone can make factory landing distances.

[Miles Magister]

PD,

For AOC work you should have a contaminated ops section in your ops manual. What is in there is the legal authority as it will have been accepted by your controlling authority. If you do not have such a section in your ops manual then it probably is not legal.

For private ops the flight manual is the legal authority.

If in doubt, there is no doubt. Stay safe.

MM