Dozy
In the event, the crew spotted the airfield late, and noticed that the spectators were lined up on the grass strip, not the paved strip on which they had been briefed. At this point the crew would have been well within their rights to abort the flypast altogether, and press on to the sightseeing trip over the Pyrenees which made up the latter part of their flightplan. Instead, the PIC elected to perform an unauthorised approach maneouvre to match the grass strip, even though they were considerably high and fast to do so.
Wherever you got that information from, it does not look right. The heading difference between the flown grass strip track and the paved strip is 035 degrees, and would have required a total different track from beginning and flight over the houses of Habsheim, which was not permitted for airshow traffic. They would have flown a different track to approach the airfield some miles out with the track of 020 degrees for the paved strip. But the track was flown along the east side of the highway Basel-Straßbourg which is about heading 345 like the grass strip and which is over thin populated areas and offers good visual clues, which makes sense.
The failure was not maintaining the intended altitude of 100 feet AGL. I could go over and measure those trees today after they continued to grow another 25 years, but i doubt that i could find a tree today with a hight of 100 feet.
You may check my points by the maps published under
Habsheim cartes crash
Edit: You might refer to the article in flight international edition 17.april 1990. I think the mentioned obstacle clearance calculation by AirFrance for the paved strip was just that, a calcukation without reference to the intended approach path.
1990 | 1071 | Flight Archive