Friction coefficient

[baby hormones]

Hi Guys,

Most places use 91 92 93 etc for braking action. This METAR shows Eastern Europe apt,

18150060.

Please could anybody direct me to a table or something to convert the friction coefficient to braking action.

Many Thanks in advance

BH

[Spitoon]

It's MOTNE code - can't remember how to decode it but Google MOTNE and you'll get lots of help.

[Der_dk.]

Hi!

The last two digits of the Motne code is decoded as below

Friction coefficient:

above 40 = BA Good
35-40 = BA Medium to good
30-35 = BA Medium
25-30 = BA Medium to poor
below 20 = BA Poor
And if I remember correctly 99 = BA Unreliable

Regards

DER

[Tmbstory]

For information the Code is 9 for Unreliable.

That was when I used to use this system, it may have changed

[RYR-738-JOCKEY]

First two digits: runway designator. Last two: BA.

[baby hormones]

Thanks a lot guys.

So how low would it have to get before you think about/ company ops manual says you should to be diverting? I know Ryanair/Easy have a lot of routes to Eastern europe. Does this cause any regular problems?
Just trying to get a bit of a feel for winter ops over in this neck of the woods.

Cheers

[easymoney]

Not allowed when the braking action is reported as Poor which is 0.25 friction co-efficient and below.
The MOTNE code for braking action is

91 Poor
92 Medium/Poor
93 Medium

and so on.

99 is unreliable.

All in the Ops manual Jepp Supplememnt and pre-amble.

I would guess that the 60 at the end refers to a friction co-efficient of 0.60 and therefore Good. The rest of the code seems to follow MOTNE.

Runway 18, Damp, 11% - 50%, Depth less than 1mm

[FlightDetent]

Just to make sure nothing gets lost in the translation:

Runway state messagge (referred to as MOTNE above) has the following options

// - not reported, runway not operational
99 - unreliable measurement
00 to 90 - friction coefficient reported
91, 92, 93, 94, 95 - braking action reported
96 to 98 - not used

Conversion from FC to BA for those who need to, correctly provided by Der_dk. Tmbstory and 738 Jockey not entirely correct.

For BA/FC limits (and associated cross-wind contraints!!!) use appropriate FCOM or company manuals if more restrictive. For instance LDG on poor is normally prohibited, but lading on FC 20-25 could be allowed.

OTOH many realise that there is no reliable corelation between reported deceleartion measurement and ad hoc aircraft behaviour. So, for TKOF performance some only use type of deposit and depth. Sometimes the BA/FC is not reported at all in order not to provide false and liable assumtions to operators - which I understand is UK CAA stance now. I am standing by to be soon corrected on this one. :)

FD.

[easymoney]

From the Jeppy Supplement book.


The seventh and Eighth Digits Refer to

Quote from jeppy supplement.


"The friction co-efficient is denoted by two digits or, if the co-efficient is not available, the braking action is denoted the two digits.
So the last two digits will be in this case 60 which equal a co-eff of 0.60.
or if co-eff not available the Braking action will be reported.

95 Good
94 Medium/Good
93 Medium
92 Medium/Poor
91 Poor
99 Unreliable
// Not reported AD closed

So do whatever your company ops manual states.

You are also correct in stating the 9 refers to unreliable......if it's referenced in a snotam. But MOTNE use 99 for unreliable.

[call100]

OTOH many realise that there is no reliable corelation between reported deceleartion measurement and ad hoc aircraft behaviour. So, for TKOF performance some only use type of deposit and depth. Sometimes the BA/FC is not reported at all in order not to provide false and liable assumtions to operators - which I understand is UK CAA stance now. I am standing by to be soon corrected on this one. :)

You are correct. The following document gives an idea of the reasons behind the decision.
Hope it helps..


http://www.stac.aviation-civile.gouv.fr/aoswg/Proposedamendfric_DP4.doc (http://www.stac.aviation-civile.gouv.fr/aoswg/Proposedamendfric_DP4.doc).