Radio Altimeter System

STUDENT GUIDE FOR T-1A AIRCRAFT SYSTEMS

CHAPTER TWELVE

The altitude data field shows the relative or absolute altitude of the intruder as selected by the

relative/absolute line key.

The VS arrow display indicates the vertical trend of the intruder if the rate is greater than 500

FPM. The arrow points up if the intruder is climbing, and down if descending.

1. Altitude Type Line - The altitude type line key labeled REL/ABS selects the Relative

(REL) or Absolute (ABS) altitude of the intruder aircraft. Push the REL/ABS line key to display

the selected format (green and underlined). Relative altitude is the difference between the

intruder aircraft altitude and reference aircraft altitude. This display is in hundreds of feet.

Altitude Window Line Key - The altitude window line key selects the TCAS altitude

protection window. The window defines a zone of vertical air space relative to the aircraft.

Intruders into this zone are tracked and considered potential threats. Four altitude protection

windows are provided and labeled:

ABV/BLO - The protection window is 2700 feet above and below the aircraft.

ABV/BLO - The protection window is 9900 feet above and 2700 feet below the

aircraft.

ABV/BLO - The protection window is 2700 feet above and 9900 feet below the

aircraft.

ABV/BLO - The protection window is 9900 feet above and below the aircraft.

NOTE

The underlined portion is displayed in green; without the

underline, it is displayed in white.

1208. RADIO ALTIMETER SYSTEM

The Radio Altimeter (RA) system provides indication of aircraft altitude (radio altitude) from

50-2500 feet AGL. The radio altimeter indicator displays the radio altitude if the radio altimeter

valid signal generated by the radio altimeter transceiver is detected. If the radio altimeter valid is

not detected, the indicator warning flag drops into view.

The indicator DH knob provides a means to set the radio altimeter DH. When the aircraft

reaches the selected DH, the DH light illuminates.

Radio Altimeter Warning Flag

The red warning flag falls into view if an internal failure occurs, operating power is lost, or

during a radio altimeter self-test.

NAVIGATION RADIOS

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