Flight Instruments and Avionics

Objective

To understand the basic flight instruments used for flight and their common failure modes.

To a give a student an intuitive understanding of the operation of the flight instruments, and a sense of how they will behave if they malfunction.

30 minutes

Operate on air pressure alone
Static air pressure: Altimeter, VSI
RAM air pressure: Airspeed indicator
- Airspeed = (RAM air pressure - static pressure)
- Operates with a diaphragm
Types of airspeed
- Indicated airspeed
- Calibrated airspeed
- True airspeed
- Ground speed
Airspeed indicator markings
Pitot static blockages
- RAM air block: Airspeed reads 0
- RAM air and drain hole blocked: Airspeed reads whatever it was blocked (lower if descending, higher if ascending)
Altimeter
- Remember, pressure decreases at about 1 in Hg per 1000'
- Converts ambient pressure into altimeter
- Can be compensated for non-standard pressure
- Effects of cold weather
Vertical speed indicator
- Derivative of the altimeter, the trend of the altitude
- Consists of a diaphragm with a calibrated leak