Mu Readings

[heywatchthis]

Anybody have a chart that shows the conversion from MU readings to Braking action reports. I used to have one. I want to add it to our checklist, so the next time I am on short final and they give me BA reports in MU or some other format, I can relate.

Thanks,

 

[stupidpilot]

I think its in the AIM. Here's the breakdown:
Good: > 0.50
Fair: 0.35-0.50
Poor: 0.15-0.34
Nil: < or = 0.14

Hope that helps!

 

[Mercury]

Info from the AIM

4-3-9. Runway Friction Reports and Advisories
a. Friction is defined as the ratio of the tangential force needed to maintain uniform relative motion between two contacting surfaces (aircraft tires to the pavement surface) to the perpendicular force holding them in contact (distributed aircraft weight to the aircraft tire area). Simply stated, friction quantifies slipperiness of pavement surfaces.
b. The greek letter MU (pronounced "myew"), is used to designate a friction value representing runway surface conditions.
c. MU (friction) values range from 0 to 100 where zero is the lowest friction value and 100 is the maximum friction value obtainable. For frozen contaminants on runway surfaces, a MU value of 40 or less is the level when the aircraft braking performance starts to deteriorate and directional control begins to be less responsive. The lower the MU value, the less effective braking performance becomes and the more difficult directional control becomes.
d. At airports with friction measuring devices, airport management should conduct friction measurements on runways covered with compacted snow and/or ice.
1. Numerical readings may be obtained by using any FAA approved friction measuring device. As these devices do not provide equal numerical readings on contaminated surfaces, it is necessary to designate the type of friction measuring device used.
2. When the MU value for any one-third zone of an active runway is 40 or less, a report should be given to ATC by airport management for dissemination to pilots. The report will identify the runway, the time of measurement, the type of friction measuring device used, MU values for each zone, and the contaminant conditions, e.g., wet snow, dry snow, slush, deicing chemicals, etc. Measurements for each one-third zone will be given in the direction of takeoff and landing on the runway. A report should also be given when MU values rise above 40 in all zones of a runway previously reporting a MU below 40.​

 

[Dak]

Printable table

http://web.nbaa.org/public/ops/part135/200610brakingaction.pdf

 

[real swift]

There is also an article in the December 2006 issue of Business and Commercial aviation, p.30.

 

[Dak]

PhD version (ICAO)

http://www.jaa.nl/secured/GASR/Working Papers/WP 061 Appendix 3.pdf

I guess this is the background for how they came up with it.

 

[heywatchthis]

Excellent.

I love message boards. It's an unlimited supply of information.

Just what I was looking for and more.

THANKS

 

[Say Again Over]

Yes, and been a pilot for thirty years and have yet to use an mu.

 

[Dak]

They're coming.

I would have said the same last year but just last week the PANC ATIS had them. I've seen them elsewhere too recently. I think more in the international arena though. At ANC the last two times I was there (Dec) the Mu's reported were accurate for the actual conditions.

 

[RedGuy]

What ever happened to the simple, good, fair, poor, nil? That's alot easier to understand than a bunch of numbers that really don't mean anything unless you have a magic box to disseminate them.