View Full Version : Altitude correction for Mountain wave effects

Code Blue
13th Jun 2001, 02:57
This question comes from passing comments in another thread.

Scando wrote: <font face="Verdana, Arial, Helvetica" size="2">add 500 ft pr 10 knots of wind exceeding 30 knots (max 2000ft) during the initial letdown</font>

These corrections apparently come from the Norwegian AIP (thanks Crossunder). Despite part of the Rockies being on Canadian soil, there is a dearth of info in the Canadian AIP :rolleyes:

Would any regular mountain flyers like to comment on altitude corrections - from a GA/light twin perspective?


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13th Jun 2001, 07:11
The US FAR/AIM, Airmans Informational Manual, does also contain a bit of info.

I will see if I can dig it up, or perhaps someone has it handy.


13th Jun 2001, 16:04
Got a table here in my Ops Man Gen which says:' when operating within 20nm of terrain exceeding 2000'amsl, commanders are to increase the standard moca/mora by the following amounts'.
Sadly, I don't have the instant technology to reproduce the table, but the figures for terrain fm 2000-8000' seem to fit in with scando's formula. Above 8000', the increment seems to be about 650'/10kts above 30kts windspeed.
These figures are for airline operations though, and not necessarily for light twin/ga.
Rgds to all

13th Jun 2001, 18:08
Check out the following for mountain weather and flying:

US FAA AC 00-57 "Visual Clues for Hazardous Winds"

US FAA Mountain Flying 23 minute video (on 1/2 inch VHS!)

Environment Canada Mountain Weather Services Office , Kelowna BC Canada "Aviation Weather Hazards of British Columbia and the Yukon"

There is also an unpublished report "A pilot Experiment to Define Mountain-Induced Aeronautical Hazards in the Colorado Springs Area" This work was done after the 1991 UA B737 crash at Colorado Springs and looks at low altitude (approach airspace) as well as higher elevations.

Similar work is ongoing for the Juneau Alaska area. This may be more like any work in Norway because of topographic similarities.

Also for light aircraft try the AOPA Air Safety Foundation. I believe they have materials and classes on mountain flying.

Good luck and don't become a statistic

Code Blue
13th Jun 2001, 23:57
Excellent replies & thanks

<font face="Verdana, Arial, Helvetica" size="2">Good luck and don't become a statistic</font>
I like to think I'm too much of a coward :)


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