Breaking action upon landing

[PitotTube]

So you are on approach to an airport and the TWR says

- Breaking action MEDIUM with 30% ice, Cleared to Land

You know that MEDIUM is sufficient for your landing performance, but does that 30% ice degrade the MEDIUM even further, or is the breaking action MEDIUM taking the 30% ice in question?

Thanks,
pt

[411A]

At many destinations, the 30% quoted includes the ice expected.
Last year, in Russia, it was...'cleared to land, braking condition unknown.'
Fortunately, it was quite good, considering.
Type, L1011.

Note, sliding off the end/side ain't my style, and I will divert, if necessary, make no mistake.

[PitotTube]

Thanks for answering all my questions 411A. Wow, yes the L1011 is massive so I am sure you need some serious distance to stop that aircraft.

Do you know where I can find this in writing? Where it would say which countries they would include it in the breaking action and in what countries they wouldn't?

Thanks, pT

[PEI_3721]

PitotTube, a decision to land should consider where the 30% ice is on the runway, the quality of the report, and the associated conditions.
If the ice is biased towards touchdown it would have lower risk rating than if at at the stop end. Alternatively if it was a general spread of 30%, then perhaps the runway should be considered icy throughout. IIRC, a % covering is given with respect to position along the runway.

The reporting standards vary world wide, even with ‘a reliable’ report you have to consider if you are going to risk a landing (ability to stop) based on someone else’s opinion.
It is almost impossible to judge if ‘medium’ has considered the ice or not. The two principle means of establishing a reported braking action - ground measurements of friction and PIREPS, are highly unreliable. Thus, whatever the result, it must be judged with other reports, i.e. how you ‘know’ that ‘medium’ is good enough, how was ‘medium’ derived?
There could be a vast difference between ‘wet’ and ‘dry’ ice, and similarly in how close the ground temperature is to zero.
For info see Managing Threats and Errors During Approach and Landing (http://www.flightsafety.org/files/managing_threat.ppt)

[Lightning Mate]

"Breaking action MEDIUM"

This is a small JCB or other such kit designed to destroy objects...

Wanna getta head in life?

Lern too spelll.

[Sir George Cayley]

25% coverage of contaminant or less is the usual figure but one has to interpret this. If the LDA is, say 2500m, and you are land a SAAB 340 then if that 25% is in the last third are you bothered? You might be in a 747 with a 5 kts tailwind and a min landing weight.

It's a dynamic situation and one in which P1 can earn all their salary in one landing.

The assessment of runway surface friction characteristics is an inexact science that both the FAA and EASA are currently studying.

My advice this winter is to have enough fuel to give you options if the forecast is for possible contam runways at destinations and you are not confident that the snow team will do their job. If in doubt speak to the Southwest AL 737 crew that slid off Midways runway.

Sir George Cayley

[PEI_3721]

Pitot, “…where I can find this in writing?”

ICAO Annex 14 (http://dcaa.slv.dk:8000/icaodocs/Annex%2014%20-%20Aerodromes/Annex%2014%20Volume%201,%20Aerodrome%20Design%20and%20Operat ions%20-%20Edition%20no%205.pdf), ATT 5, para 6.

Also see Annex 15 (http://dcaa.slv.dk:8000/icaodocs/Annex%2015%20-%20Aeronautical%20Information%20Services/an15_12ed.pdf), APP 2, Snowtam Format.

[PitotTube]

Thanks. I really appreciate all of your answers, even though I messed up the spelling a bit. English is not my mother tongue.

Thanks, pT