In the late 80's early 90's I worked for a Far Eastern 747 operation and as our customer did not have staff approved on our aircraft i flew with the aircraft as flight mechanic - flying spanner to the old hands. I flew into Hong Kong many times - sometimes twice in one day and sitting in the first obs seat behind the captain gave me a good insight as to how the approach should be flown. Twice I had the living crap scared out of me by bad approaches - the first time the chequer board was overshot by a fair margin and the turn became tighter and tighter until the wingtip appeared to be down among the washing lines then the GPWS started screaming Sink Rate the F/O pushed the captains hand off the throttles calmly said 'I've been here before' leveled the wings and climbed out again - the next approach was ok. The second time was a complete screw up and we again were well off - we ended up having a final turn left not right with a GPWS Sink Rate warning at a speed way over normal after touch down,max braking and reverse was held until we stopped on the runway end markings - I watched the light poles out in the water getting closer and was convinced we were going in the water.As a spectator to these incidents all I could do was sit and hope that the right thing was done-much harder than being involved in the operation of the aircraft.