Figure 3-22: Heading Invalidity (No 429 Input); Figure 3-23: Heading Invalidity (Inv 429 Input) - L3 comminications Trilogy ESI-2000 Pilot's Manual

ESI-2000 operating Instructions
ERRORS AND INVALIDITIES (Continued)
External Heading Source Invalidity (Refer to Figure 3-22, 3-23, 3-24)
Release 1.2. If external heading source data is lost or becomes invalid
during operation the heading tape is filled with a red "X" and the heading
digital readout is removed, replaced by either a "No 429 Input" or "Inv 429
Input" or "429 Failed" message.
If heading data becomes valid the display elements automatically reset to
normal operation. A re-alignment is recommended.
If invalidity continues to be observed refer to Chapter 4 Troubleshooting.

Figure 3-22: Heading Invalidity (No 429 Input)

Figure 3-23: Heading Invalidity (Inv 429 Input)

Pilot's Guide 3-17