Originally Posted by
Keith.
The video indicated that just after the tap on the shoulder, there was impact showing debris coming in from the front passenger's right seat. I realise that the ascending helicopter was to the left of the descending helicopter, but the debris to the front right might indicate that the ascending helicopter had passed under and collided on the right cabin of the descending helicopter.
Approach was from the left and below and contact was made by the ascending blades on the front right of the cabin.
Reasonable ?
The rotor blades on an EC130 rotate clockwise when viewed from above, with tip speeds of 420kts. The main impact forces appear to be from the blades of the ascending helicopter impacting the fore-right section of the cabin on the descending helicopter - note the failed door frame pillar on the right side of the cabin but the intact pillar on the pilot's (left) side in photos of the wreckage.
Even if the relative motion of the ascending helicopter is from left to right as viewed from the perspective of the descending helicopter, the high tip speeds of the main rotor mean that the retreating blade still moves from right to left relative to the descending helicopter's nose, causing the impact and debris to appear from the right as seen in the video.