Re: Air Speed

Date:         25 Sep 97 01:39:44 
From: (Robert Dorsett)
Organization: Netcom Online Communications Services (408-241-9760 login: guest)
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In article <airliners.1997.2180@ohare.Chicago.COM> "Ruth or Doug Blue" <> writes:
>Several of us (non pilots) have been told that a large passenger jet should
>not descend below about 10,000 feet at more than about 250 knots air speed
>in controlled flight. Should that speed be inadvertently exceeded, what
>sort of problems would arise? We felt that they might be related mainly to
>temperature increase in the denser air, but wondered if anyone had detailed

The speed restriction varies by country, and is solely an issue of
traffic detection and avoidance.  When you're under 10,000', you're near
a terminal area, and can bet there are a lot of other airplanes in
the terminal area.  At faster speeds:

- Your time to detect other airplanes is reduced.
- Your maneuvering capability is reduced (any maneuver requires more
  loading and increases passenger discomfort).
- Standard ATC procedures (holding patterns, etc) will cover a much larger
  area, increasing the difficulty of maintaining traffic separation.
- The likelihood of error during the approach segment increases.

Some countries (including many in Europe and the third world) allow ATC to
dictate the speed restrictions, depending on traffic.

At sea level, the barber pole (VMO limits) on the 727 is around 350

Robert Dorsett                         Moderator, sci.aeronautics.simulation               

           "Bother," said Pooh when his engine quit on take-off.