Flight Instruments Flashcards
What instruments operate from the pitot/static system?
The pitot static system operates the altimeter, vertical speed indicator, and airspeed indicator
How does an altimeter work?
In an altimeter, aneroid wafers expand and contract as atmospheric pressure changes, and through a shaft and gear linkage, rotate pointers on the dial of the instrument.
What are the limitations that a pressure altimeter is subject to?
Nonstandard pressure and temperature.
a. Temperature variations expand or contract the atmosphere and raise or lower pressure levels that the altimeter senses
- On a warm day - the pressure level is higher than on a standard day. Altimeter indicates lower than actual.
- On a cold day - pressure level is lower than on standard. Indicates higher than actual.
b. Changes in surface pressure also affect pressure levels at altitude.
- higher than standard pressure - the pressure level is higher than on a standard day. The altimeter indicates lower than actual altitude.
- Lower than standard pressure - the pressure level is lower than standard. Indicates higher than actual.
* HIgh to low or hot to cold look out below*
What is the maximum allowable error for an altimeter IFR flight
off by more than 75 feet
Indicated altitude -
read of the face of altimeter
pressure altitude -
Indicated altitude with 29.92 set in the Kollsman window
True altitude -
heigh above sea level. Use the flight computer
Density altitude -
Pressure altitude corrected for nonstandard temperature
Absolute altitude -
Heigh above ground. Subtract the terrain elevation from true altitude
How does the airspeed indicator operate
The airspeed indicator measures the difference between ram pressure from the pitot head and atmospheric pressure form the static source
What are the limitations the airspeed indicator is subject to?
It must have proper flow of air int he pitot/static system
What are the errors that the airspeed indicator is subject to?
Position error - Static ports sense erroneous static pressure; slipstream flow disrupts. Varies with airspeed, altitude, configuration
- Density error - changes in altitude and temperature are not compensated for by instrument
- Compressibility error - caused by the packing of air into the pitot tube at high airspeeds, resulting in higher than normal indications. Usually above 180 KIAS
IAS
Indicated Airspeed - The speed of the airplane read off the airspeed indicator
CAS
Calibrated airspeed - the airspeed indicator reading corrected for position and instrument errors; equal to TAS at sea level in standard atmosphere. The color coding for various design speeds marked on the airspeed indicators may be IAS or CAS
EAS
Equivalent Airspeed - the AS reading corrected for position instrument error and for adiabatic compressible flow for the particular altitude; equal to CAS at sea level in standard atmosphere
TAS
True airspeed - the speed of the airplane in relation to the air mass in which it is flying
Aircraft speed pneumonic device?
ICET
White arc
Flap Operation range
Bottom of white arc
Flaps down stall speed
Top of white arc
Maximum airspeed for flaps down flight
Green arc
normal operating range
Bottom of green arc
Flaps up stall speed