To add some clarification to the system on the -300, the normal gear indication system is controled by the PSEU (proximity switch electronic unit) and it also provides info the EGPWS to provide "Too Low Gear" callout. The alternate system illuminates the alternate gear verification lights and nothing else.
If the PSEU has a fault then you should get a LDG GEAR INOP caution light and will be required to do an alternate gear extension.
In this case there was no caution light but the evidence suggested that the PSEU was not sensing that the nose gear was down. (the evidence being that the alternate lights indicated down and locked but the normal lights were not)
The Capt knew that if the alternate lights were green the gear was down and locked.
Based on the knowledge that the PSEU must have had some sought of fault that had not illuminated the associated caution light the Capt would not have been surprised to hear the EGPWS warning because it gets its info from the same system, therefore he elected to continue the approach.
Now you can debate that decision till the cows come home but if the PSEU was at fault you would get the same callout every approach until you pulled its circuit breaker so how many times should he have gone around?
Last edited by aluminium hail; 5th Nov 2012 at 21:44.