Re: altitude questions

From: (Robert Dorsett)
Organization: Capital Area Central Texas UNIX Society, Austin, Tx
Date:         01 Nov 93 14:04:50 PST
References:   1
Followups:    1
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In article <airliners.1993.687@ohare.Chicago.COM> campbjw@wkuvx1.bitnet writes:
>In the Nashville, TN area where I live, Air Traffic Control usually
>assigns commercial flights to altitude levels of 28000 to 33000 feet -
>what is the highest common flight level used 

Controlled airspace extends to FL600.  Above that, it's VFR.

>and what is the maximum
>flight level the average commercial plane can attain?

41,000' is a common "maximum operating" number.  31,000-39,000' is more 
typical for medium and long-range flight.  I'd guess an absolute altitude
for a commercial airliner around 50,000'.

>Related to
>that, what are the limiting factors in altitude attainment for
>commercial planes?

The cost in energy of getting up there (may not be worth the while), and
pressurization limitations (Concorde needs a somewhat more robust 
pressurization system for its high-high altitude flight).  If it's desired
to keep an 8.5 differential, with a maximum cabin altitude of 8,000', 
the airplane is limited to around 40,000'.  If you can raise the max.
cabin altitude to 10,000', the airplane is limited to 50,000'.  Whether
it can get to either altitude is another issue entirely.

>  Are these altitudes typical for trans-oceanic
>flights?  What are typical altitudes for European flights - I assume
>somewhat less since distances travelled are often less than in
>North America?  

See above.  You can use the same rule-of thumb as for short commuter hops
in the US: Southwest, for example, tops at 21,000' in its 30-minute, 150-
mile flight between Austin and Houston.

>Does direction make much difference in altitude

Normally, aircraft are stacked at 2000' increments above FL290.  In general,
eastbound flights are stacked in 4000' increments starting at FL290.  West-
bound flights are stacked at 4000' intervales beginning at FL310.  Many
countries have variations on this; Eastern European countries do things
in meters.

Robert Dorsett!!rdd