Regarding friendly fire incidents involving heavy bombers hitting Allied ground forces, we should remember that the heavies were not organized, equipped or trained to attack targets close to our own forces. Furthermore their equipment was very primitive compared to today and I believe that what sophisticated electronic navigation devices were in use did not cover Normandy. To hit a ground target successfully depended upon the navigator guiding the pilot to the target area, the pilot flying the aircraft accurately and the bomb aimer identifying the target and selecting the correct point of aim.
In Bomber Command the aircraft did not attack in formation, but rather flew in a bomber stream (a night bombing tactic) and each attacked the target individually following the guidance of a master bomber who stayed over the target area 'coaching' aircraft to hit coloured markers dropped by the pathfinder force. Pathfinders were not employed in great numbers during the two incidents Parkie raised. In any case, in the second the colour of the markers in use that day was yellow, which also was the colour of the panels and smoke used by ground forces to identify their positions to tactical aircraft. After the incident Harris was prepared to make an issue of this, until his staff discovered that Eisenhoer's headquarters had sent them a letter to the effect that yellow was to be used only to identify friendly forces. This letter had been misfiled.
As Bomber Harris wrote in his covering letter to the investigation of the Tractable short bombing on 14 August 1944, and I am paraphrasing, neither the pilot nor the navigator could actually see the target being attacked, and the bomb aimers were selected from those member of the potential aircrew trainee pool that were not considered to suitable material to be trained as pilots or navigators.
The situation was darn near successproof and the results in Normandy, where most attempts to use heavy bombers to support ground forces resulted in friendly fire incidents, bear that out.