L-1011 Autoflight: DUAL A/L NOT AVAIL LIGHT (22-15)

The DUAL A/L NOT AVAIL light (A/L .. Autoland), located on the Pilot's caution and warning panel, serves as a cruise monitor that forewarns of the unavailability of dual A/L whenever it detects a failure that may preclude achievement of dual A/L track status. Its activation is not dependent upon prior selection of A/L. Its purpose is to allow ample time to refile if the destination forecast would require dual A/L.

This warning can be reset and will remain out until the landing roll, when it will be recalled automatically as the airspeed passes through 90 knots. The recall serves as a reminder for postflight logbook entry and as an advisory message for maintenance personnel and for the next flight crew, if not corrected.