Controllers in the tower do not have a good visual perspective to see runway alignment. I don't think they would have caught this.
At night, there are many visual cues to see the runway environment - it sounds to me like this complacent pilot ignored many red flags and was about to drive his plane on top of those on the taxiway.
A big heavy airliner can't just stop its decent instantly; it's a good thing that pilot on the ground chimed in when he did.
I betcha the landing pilot won't have a job pretty soon.
When you're descending at a rate suitable for human cargo in good weather there's plenty of room to maneuver.
A C-5 that's trying to drop out of the sky ASAP before anyone can shoot at it is a different story.
The pilot and copilot were clearly in WTF mode since there were planes on what they thought was the runway. If nobody had spoken up it would likely have gone back and fourth between them and the tower a few times ("are you sure the runway is clear?") and in all likelihood they would have caught it. If they didn't the pilots would have likely requested to go around. Backing off of what you're doing and assessing the situation when anything is not quite right is SOP in every facet of aviation.
Radar displays are not going to accurately display a displacement of 150m. They're set up for broader area surveillance.
Edit: here's a good example of a terminal radar display. The two parallel diagonal lines are the extended centerlines of two runways that are about 1570m apart (Athens airport, LGAV).
At night, there are many visual cues to see the runway environment - it sounds to me like this complacent pilot ignored many red flags and was about to drive his plane on top of those on the taxiway.
A big heavy airliner can't just stop its decent instantly; it's a good thing that pilot on the ground chimed in when he did.
I betcha the landing pilot won't have a job pretty soon.