DOCUMENT:Q264616  07-MAY-2002  [homegame]
TITLE   :FS2000: Differences Between True and Indicated Air Speeds
PRODUCT :Microsoft Home Games
PROD/VER:WINDOWS:
OPER/SYS:
KEYWORDS:kbref fsim kbimu

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The information in this article applies to:

 - Microsoft Flight Simulator 2000 
 - Microsoft Flight Simulator 2000 Professional Edition 
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SUMMARY
=======

This article describes true air speed, indicated air speed, and how to derive
true air speed from indicated air speed based on altitude.

MORE INFORMATION
================

True Air Speed
--------------

True air speed is the actual speed at which an aircraft moves from one point to
another. True air speed can be affected by the altitude of the aircraft, but in
most cases the effect is minimal because most aircraft fly at a maximum altitude
of seven to nine miles. Some large aircraft can fly at higher altitudes. For
example, the Concorde can fly at a maximum altitude of approximately eleven
miles.

Indicated Air Speed
-------------------

The air speed displayed on the Air Speed Indicator on the instrument panel in
your aircraft is the indicated air speed. Indicated air speed is the speed at
which an aircraft moves through the air, and it can be affected significantly by
altitude and wind direction.

The Air Speed Indicator works by comparing the air pressure inside the Pilot Tube
to the air pressure inside the aircraft cabin. The Pilot Tube is a hollow probe
that points directly forward into the oncoming air.

Changes in altitude can affect indicated air speed. As the altitude of the
aircraft increases, the air pressure in the Pilot Tube decreases, causing the
indicated air speed to decrease.

Assuming no effects from wind, the following table lists the true air speed in
nautical miles-per-hour (knots) for an aircraft traveling at 400 knots at
altitudes between 1000 feet and 25000 feet.

+---------------------------------------------------+
| Altitude   | Indicated air speed | True air speed | 
+---------------------------------------------------+
| 1000 feet  | 400                 | 405            | 
+---------------------------------------------------+
| 4000 feet  | 400                 | 421.7          | 
+---------------------------------------------------+
| 8000 feet  | 400                 | 445            | 
+---------------------------------------------------+
| 10000 feet | 400                 | 457.2          | 
+---------------------------------------------------+
| 15000 feet | 400                 | 489.1          | 
+---------------------------------------------------+
| 18000 feet | 400                 | 510.1          | 
+---------------------------------------------------+
| 22000 feet | 400                 | 539.4          | 
+---------------------------------------------------+
| 24000 feet | 400                 | 554.7          | 
+---------------------------------------------------+
| 25000 feet | 400                 | 562.2          | 
+---------------------------------------------------+

Additional query words: msgame fs2k flightsim fsim airspeed mph

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Keywords          : kbref fsim kbimu 
Technology        : kbGamesSearch kbFlightSimSearch
Version           : WINDOWS:
Issue type        : kbinfo

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