Originally Posted by
ETOPS
I still have nightmares but here goes..........
Being a single channel/fail passive system there were numerous monitors built into the autopilot the last one being me! The correct ILS frequency being selected and the inbound course dialled into both direction indicators meant you could press the autoland test button - a successful outcome was a black and white "dolls eye" briefly showing on an indicator. Once established on the ILS both pilots would select a switch on their DI to lock onto the signal - seem to remember this was termed "beaming up" ?
A last check of the weather/RVR and minima set on the Rad alt (50 ft decision height) meant my job was to gingerly operate the "Prime Land" switch. When engaged it allowed the autopilot to perform its tricks and the approach to descend below CAT1 minima. It was held in the engaged position magnetically thus would disconnect if any fault occurred - that being a fairly regular occurence! If it did drop out a loud warning sounded and a bright red warning light illuminated - that always made me jump and I had to call "go-around" above 50 radio or "LAND MANUAL!!" below 50 ft - and yes I was speaking in capitals
If the system worked the result was usually a pretty decent landing - the results of a manual touchdown from 50 ft in poor viz were .................variable.
Brilliant. Brit engineering at its finest. ! That said I flew the Classic for a while. Autolands were something of a variable feast.