EU-OPS reference regarding X-wind limits on a contaminated runway

[buzzc152]

Hi all

I did a search but couldn't find what I'm looking for ;

My aircraft like any other has lower x-wind limitations when operating on runways with reduced braking action. I'm looking for the actual EU-OPs reference that says operators should have such limits in place and if they define how those limits are calculated.

Thanks
Buzz

[Yak97]

Surely the x wind limits are a function of the design of the aircraft and are thus stated in the AFM, to which the operator must comply? I suppose the operator could establish lower limits but could not set higher as would therefore be outside AFM.

[buzzc152]

In my aircraft (HS-125) it's not defined in the AFM but our company does have stated limits in our Ops manual which are applicable to all the different types we operate.

To expand my question a bit, as you've rightly said, these limits should type specific, but in the absence of any AFM guidance is there an industry standard or EU-Ops (or FAA) recommendation ? For example, 1/2 the max dry runway xwind limit for med-good braking action, 1/4 for medium, 1/8 med-poor etc etc (I've made those numbers up).

Thanks
Buzz

[Ops_Room_Junkie]

To my knowledge there are no X-wind limitations guideline/reccomedations that I am aware of in EU-OPS (to try and confirm this I just did a word search for 'wind' over the whole document in .pdf).
It is specific to your aircraft and to a degree your operating procedures.

We issue Airbus 'recommendations' in our performance folders but these are not based on actual landing/take-off data (Airbus do not have the data I understand) but on the results of simulations modelled to account for reduced runway friction. We treat these as limitations.

In addition we issue company recommended guidelines for max x-wind for ops on contaminated runways, based on our actual experience of such operations. This are lower than the Airbus 'recommendations'.!

I hope that helps, but I guess it doesn't!

[Ops_Room_Junkie]

To allow you to 'peep' inside the figures we publish are:

AFM
Dry/Wet BA Good/Good Medium 29kts take-off / 33kts ldg
Slush/Dry Snow BA Medium/Medium Poor 20-25kts
Dry Snow/
stdg water/
wet snow BA Poor 15kts
Icy Poor/Unreliable 5kts

Our company recommednations are: (ALWAYS LOWER)

Dry/Wet BA Good 25kts
Dry/Wet BA Good Medium 20kts
Slush/Dry Snow BA Medium 15kts
Slush/Dry Snow BA Medium Poor 10kts
Dry Snow/
stdg water/
wet snow BA Poor 5kts
Icy take-off not permitted

[Sir George Cayley]

Braking Action (BA) in words - Good, Medium and Poor only refer to Compacted Snow and Ice. See ICAO Annex 14 Green Pages and UK AIP Aerodrome Availability.

Also 'Unreliable' or 9 on the SNOWTAM could well be the machine is broke, so taking a 5kt crosswind limit may be a tad limiting.

For the certification basis for a/c look for either FAR Part 25 or in Europe CS 25.

Hope this helps

Sir George Cayley

[safetypee]

There are no EU regulatory (certification or operational) references to crosswind limits in contaminated conditions.
Some good guidance is given in Canadian documentation (AIP) associated with CRFI. Although the frictional aspects do not apply outside Canada unless the appropriate figures are provided, the crosswind information does provide very sensible information.

See para 1.6.6, Table 3, AIR - 1.0 GENERAL INFORMATION - Transport Canada (http://www.tc.gc.ca/eng/civilaviation/publications/tp14371-air-1-0-462.htm#1-6) Note that the friction index (CRFI) is not the same as runway friction.
The description of the runway condition can be correlated with the friction index in table 3 by using the contaminant information in Tables 4a & b.
As an example, loose snow up to 25 mm gives a CRFI ranging 0.2 – 0.4 (table 4a), which would relate to a maximum crosswind component of 15 kts (Table 3), but with a lower friction (0.2) in similar conditions, the crosswind component would be greatly reduced.
Note the text with Table 3, in particular “The case where the surface temperature is just at the melting point (i.e. about 0°C) may be an exception, as a water film may form from surface melting, which could induce slippery conditions with CRFIs less than those in Table 4a.”

http://flightsafety.org/files/alar_bn8-7-crosswind.pdf
http://www.nats-uk.ead-it.com/aip/current/aic/EG_Circ_2007_P_086_en.pdf
http://www.nlr.nl/id~4382/l~en.pdf

CS-25 AMC 25.1591 gives the performance basis for contaminated operations.