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ItsAjob
29th Dec 2009, 10:06
I was looking for the Airbus briefing notes on landing on contaminated and wet runways but it appears to have been taken off the Airbus site.

When friction co efficient or braking action is reported I understand the only limitation published is in fcom 2 - crosswind.

So technically, if braking action poor is reported, or a low co efficient, we have no way of calculating landing distance unless they give us a full contamination depth report?

FLEXPWR
29th Dec 2009, 12:45
Some airlines procedures do not allow to dispatch an aircraft (A320 in question) to an airport/runway where braking action is poor or unreliable (note, unreliable is different from not available), regardless of crosswind conditions. (ie braking coeff at or below 0.25)

Flex

Dani
29th Dec 2009, 23:09
I wasn't aware that there are manuals on an Airbus site?

For your daily operation, please use the tables provided by your operator.

Are you a a PC pilot or interested pax? You might want to check public sites where you get old FCOMs or check SmartCockpit.com.

Dani

Thunderbug
30th Dec 2009, 09:54
My operator provides us with figures for:

LANDING DISTANCE REQUIRED ON ICY / SLIPPERY RUNWAYS

The landing distances required for Icy/Slippery runway conditions are based on the same procedures and threshold speeds as in the normal landing case but using FULL reverse thrust on all engines, reduced braking coefficient and a 1.15 factor on the actual distance. The distances below are valid for use at airfield elevations up to 4000ft.
With a thrust reverser inoperative or a tailwind, landing on Icy/Slippery runways should be avoided as the landing distance required is likely to exceed the runway length available.

These figures also provide the guidance on the landing distances required when the Degraded Braking Action is ‘Medium/Poor’ or ‘Poor’

We can land, but cannot depart from a runway that is Icy / Slippery

During the recent poor weather our management issued us a notice to remind us that actual conditions are rarely as black & white as portrayed in the manuals!
The quality and and accuracy of braking action & contamination reports together with the variable nature of the grip / friction at different points on the runway require a cautious approach.

T'Bug

PEI_3721
1st Jan 2010, 19:25
It’s probable that Airbus has aligned its contaminated performance data with the requirements of CS 25.1591 which enables contaminant type and depth to be used in the calculations. However, if the reported conditions are poor (low coefficient) then the lower risk option is to land elsewhere or wait until the runway is cleared;- as recommended by UK AIC 86/2007 and AMC CS 25.1591 para 8.0.
Even if you could calculate the landing-distance in such conditions the margin of error, and thus risk, could be very high.

The example from Thunderbug appears to follow CS 25.1591 by stating that full reverse thrust is considered, i.e. no additional safety margin available from reverse.
However, it is surprising that without additional explanation, normal procedures and speed variation can be used. Para 8.3 of the AMC requires advice on approach speed increments above Vref, and if used, a distance correction should be provided.

An operator using actual contaminated distance with a 1.15 factor (as required by EU-OPS 1) might only have data which moves a theoretical minimum to a practical achievable minimum distance, i.e. there is no runway distance safety factor as for landings on non contaminated runways.