[robtek]

Afaik you have a guide beam that the plane rides to the target.
Then you have two intersecting beams.
The position of the first beam isn't that important, just a few km before the target.
The second beam however must be placed exactly in the middle between the first beam and the target!
When the plane reaches the first intersecting beam the pilot starts a special stopwatch,
now the speed and altitude must be kept as exact as possible and of course the guide beam must be ridden!
Upon reaching the second intersecting beam the pilot presses a second button on the stopwatch, which now runs backward.
Upon reaching zero the stopwatch! releases the bombs.