STUDENT GUIDE FOR T-1A AIRCRAFT SYSTEMS
A display dim control
Two reversionary annunciators
A reversionary switch
Air Data Computer
Two ADCs, located in the avionics rack, are the key components of the ADS. They receive the
pitot static air inputs, outside air temperature inputs and develop airspeed, altitude and
temperature parameters for use throughout the navigation system.
Two altimeters, one on each instrument panel, display baro corrected altitude, preselected
altitude, barometric pressure, and ADC failures.
Baro Corrected Altitude
The green numeric display indicates baro corrected altitude. The units and tens digits are always
displayed as zero. The green altitude pointer rotates around a scale with 20-foot increments.
Each pointer revolution equals 1000 feet of altitude.
Preselected Altitude Display
The cyan numeric display indicates preselected altitude as set by the altitude preselect knob.
Rotating the preselect knob changes the preselect value in 100-foot increments on both P's
altimeters. The display flashes and the audio alert is generated when approaching the preselected
altitude + 1000 feet. The display remains steady at the capture altitude + 200 feet and the audio
alert is silenced. The display is yellow and flashes when the aircraft deviates + 200 feet from the
captured altitude. The display is magenta when the P and CP altimeter preselect values do not
agree. The display blanks when ADC preselect data is invalid.
Barometric Pressure Display
The cyan numeric display indicates the amount of barometric pressure correction in inches of
mercury. Dashes are displayed when ADC altitude data is invalid.
Mach Speed Indicator
Two MSIs, one located on each instrument panel, display Indicated Airspeed (IAS), mach speed,
IAS/mach reference, True Airspeed (TAS), temperature, and ADC reversion and fail
annunciation. The MSI display blanks and a red ADC annunciation flashes for 10 seconds then
becomes steady when the ADC fails.