And it may not be a perfect solution, but GPS altitude
readout may be independent of baro altitude.



"Fred G. Black" wrote in message
...
|M wrote:
| BTW, FAR 91.144 restricts flight operations when
barometric pressure
| exceeds 31 inch mercury. Any idea why? (note this
restriction applies
| to VFR traffic a well).
|
| The "why" is that the altimeter setting range on most
altimeters doesn't
| go past 31.00". Does anyone have an example of a NOTAM
under 91.144?
| (how restrictive is it).
|
| The rules that apply in Canada are a bit more explicit:
|
http://www.tc.gc.ca/CivilAviation/pu...12-1.htm#12-12
|
| Basically it says
| - for enroute, set the altimeter to 31"
| - for IFR approaches, set the altimeter to the actual
altimeter setting
| if able, otherwise set it to 31" and adjust the altitude
minima (add
| 100' and 1/4 SM per 0.1" above 31.00")
| - aerodromes which cannot report the actual altimeter
setting are
| restricted to VFR.
| -"For aircraft operating VFR, no additional restrictions
apply; however,
| extra diligence in flight planning and in operating in
these conditions
| is essential. "