The problem with a pan down is that there isn't enough footage of the action from high up to merge with any images of this sort.
A pan up may be possible because a lot of the bunker footage is shot from the ground pointing slightly upwards which might be merged with a new model shot.
The image I made certainly couldn't be used because it's from very high up (to get the bombers in) and a scale very unsuitable for a shot of that kind.