23-06-2012, 05:57 PM
Instrumentation
intrumentation.ppt (Size: 1.12 MB / Downloads: 165)
Pitot-static system
Operates in response to air pressure
Two air pressures:
Static pressure
Taken from static vents, powers all three pitot-static system instruments (ASI, VSI, Altimeter)
Impact pressure
Powers airspeedindicator only
Static System & Altimetry
Static system powers altimeter
Altimeter operates as a barometer
Set altimeter on the ground to local settings
Air pressure decreases at a constant rate per foot increased in lower atmosphere (approximately 1000’ per 1” Hg)
Nonstandard temperature and pressure affect altimeter
Altimeter
As static pressure decreases, indicated altitude increases
Altimeter setting is adjustable in “Kohlsman Window”, aka Altimeter Setting Window
Local altimeter setting willcause the instrument to readthe approximate fieldelevation when located onthe ground at the airport
Reset altimeter to 29.92when climbing through18,000 feet.
Altitude Terminology
Indicated Altitude
Altitude read on the altimeter when it is set to the current local altimeter setting
Absolute altitude
Height above the surface
True altitude
True height above Mean Sea Level (MSL)
Pressure altitude
Altitude indicated whenever the altimeter setting dial is set to 29.92 (Standard Datum Plane)
Density altitude
Pressure altitude corrected for non-standard temperature and/or pressure.