Standby Barometric Altimeter Failure

T-45C TS & ADV BIFP-09

Instrument Failures

Takeoff

20 units (full flaps)

Climb

10-11 units

Maximum range

12-13 units

Approach

17 units

The procedure for dealing with a combined standby airspeed indicator failure, plus a

display system airspeed failure is:

Check PITOT HEAT -- ON.

Report the failure to ATC.

Fly AOA in place of airspeed.

Be aware that display system navigation information that uses airspeed may be

missing or incorrect.

5. Watch for other indications of pitot static system problems.

6. Land as soon as practicable.

STANDBY BAROMETRIC ALTIMETER FAILURE 1.8.1.7.9.2

You have two options to make up for the loss of the standby barometric altimeter. The

system may or may not show proper altitude on display system altitude readouts.

First, you can use the radar altimeter for height above ground for altitudes up to 5,000 ft

AGL. You must add ground elevation to radar altitude to approximate mean sea level

(MSL) altitudes.

Second, you can obtain backup altitude information from the cabin pressure altimeter.

This instrument should be considered accurate to +/-500 ft and is primarily useful at

altitudes above 5,000 ft AGL, peak altitude for the radar altimeter. In order to use the

cabin pressure altimeter above 5,000 ft MSL, you will have to depressurize the cockpit,

and depressurized flight above 25,000 ft is prohibited.

Don’t forget to cross-check your other pitot static system instruments (airspeed and

vertical velocity indicator) to determine if they are operating correctly. The vertical

velocity indication on the ADI display is generated by the GINA and is not affected by a

pitot static system malfunction.

The procedure for dealing with a standby barometric altimeter failure that also includes

display system barometric altitude readout failure is:

1. Check PITOT HEAT -- ON.

2. Report altimeter failure to ATC.

3. Use the radar and the cabin pressure altimeters to determine altitude (depressurize

cockpit if required).

(8-99) Original

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