The fact that the L Rad Alt has failed is largely irrelevant to the flight crew and there's no associated procedure in the QRH. In-flight, the flight crew's actions will be dictated by any EICAS alert messages that appear on the upper EICAS. In this case, the failure of the L Rad Alt will result in a 'NO LAND 3' EICAS alert, due to the loss of redundancy. Various other failures will also trigger a 'NO LAND 3' EICAS alert. It doesn't really matter to the flight crew what type of failure triggered the alert; what matters is that the 'NO LAND 3' indicates that the aircraft's autoland capability has been downgraded.
From the QRH:
NO LAND 3 - "Condition: The autoland system does not have redundancy for triple channel autoland."
From FCOM3 (Flight Operations)\Supplementary Procedures\Flight Procedures\Low Weather Minima Operations:
"At 1500 ft. RA the AFDS changes to LAND 3. AFDS changes from 1500 ft to the alert height can occur at any time downgrading the system from fail operational to fail passive. This is indicated by LAND 2 on the AFDS. The AFDS must annunciate LAND 3 for CAT 3B operations and LAND 2 for CAT 3A or CAT 2 operations."
What that means is that with a 'NO LAND 3' EICAS alert, the aircraft cannot do a CAT 3B approach. It can, however, do a CAT 3A or CAT 2 approach, provided LAND 2 is annunciated on the AFDS when the aircraft passes 1,500 ft RA during the approach.
Hope that makes sense.
Last edited by BuzzBox; 25th April 2009 at 00:01.