L-1011 Flight Instruments: Attitude Indicator Failures (31-19)

• The Attitude Flag appears with first INS failure or instrument failure. 
• The Speed Flag appears if there is a power failure. The speed command pointer will bias out of view with an invalid signal. 
• The expanded localizer deviation indicator is covered. The shutter appears if a localizer frequency is tuned and there is an invalid input or there is a power supply failure. Also when a VOR frequency is tuned. 
• Flight Director flags come into view with signal loss from APFDS computers, power failure or incompatible frequencies. 
• The Glideslope Flag shows when power is lost or the GS signal is too far out or out of range.