AS a Avionics engineer on L1011s with British Airways I must protest at the claim Lockheeds pioneered Cat 3 landings I also worked on the DH121 Trident which was doing Cat3b landings way back in the early 70s long before we had our Tristars, Smiths Autopilot division pioneered automatic landings way back in the 50/60s and the Trident was built with that system in mind Triple Hydralics, Triple none parallel electrical sytems as demanded by the C.A.A at the time and a host of safety measures including multi system reading flight data recording .I admit the L1011 system was better in the end but it had laser gyros and other better electronics which were not available to the Trident as they were in their infancy nor developed at the time the Smiths system was conceived.
As for engaging the auto land system on the Tristar you normally flew with either "A" or "B" autopilot engaged the other had to engaged as well but I,m afraid the routine after that has become a "Senior Moment" and I can't remember the sequence after , I can remember the test set transmitted a glide slope signal and the height was decreased until we got it to land this had to be done slowly or the horizontal stabilzer used to move too much and the nose would oscillate trying to follow the gyro system.
Last edited by avionic type; 4th Mar 2010 at 19:58.