1–5 FD/LS OPERATION – GENERAL (cont)

TM 1–1520–238–T–1 1–14 Change 5 1–5 FD/LS OPERATION – GENERAL (cont) 1–5 (2) When boresight correctors are entered via the DEK (ADC) or CDU (ADD) the checksum for these values is calculated for each system. These checksums are monitored continuously following power-up. (3) Upon detection of a checksum error, a high-action- display (HAD) message is displayed to the appropriate crew member in the sight status or weapon status character field. The affected system(s) boresight correctors for the system(s) defaults automatically to zero until the operator intervenes. (4) In order not to mask lower priority weapon status messages, the boresight (BST) message is blinked. The messages to be displayed are correlated to the systems affected as follows: System In Use Message TADS TADSBST? PNVS PNVSBST? GUN GUN BST? ROCKETS/ MISSILES PYLNBST? (5) For checksum errors, FD/LS does not set the system status indicators signifying a failure for the respective system. Therefore, invalid boresight correctors do not result in lighting of caution and warning indicators, or display of system failure messages. (6) When the flashing FD/LS prompt is initiated (ADC) or FDLS message appears on the CDU (ADD), the operator sets the DATA ENTRY switch to the FD/LS position (ADC) or selects the FDLS FAB on the CDU (ADD). Typical boresight checksum error related FD/LS continuous messages and corresponding maintenance messages are as follows: