Question for 737AvEng: In case you didn't have the time to read the entire thread, one of the questions hotly debated earlier was: Why would RA1 logic be programmed to send a Retard signal (flare mode?) to the A/T upon indicating -8 feet when auto land was not selected and the approach was flown only on one coupled A/P in GS capture mode? I'm not a 737 jock, but several contributors had mentioned, just for the record, that 1 A/P can in fact do a full coupled CAT-III landing. OK, but in this case, the engaged A/P was not in A/L auto land mode
I've actually read the whole thread, and what a thread it has been! I believe I posted this info and others have pointed out that the right radio alitimeter feeds FCC-B and that the left radio alitimeter feeds the autothrottle computer (when no failure is present).
The autothrottle computer on the 737NG is programmed to retard even when not in autoland. Conditions are to be:
On G/S
Flaps > 12.5 degrees
27' or less of radio altitude
Irrelevant here. The RADALT was not showing FAIL.
Agreed and I have stated this before as well. The intent of my comment about failure signals is the reliablity of the radio altimeter transceiver. Rananim asked if the #1 rad alt HAD sent out a fail, would this have occured.
Graybeard said:
Pulling the #1 radalt CB upon receiving the false gear warning would have prevented the AT Retard. End.
Agreed, but I will let you folks debate the action of pulling CB's in flight.
Wizofoz said:
As would disconnecting the AT
Agreed and maybe this should be SOP when noting erroneous radio altitude below 2500'.