Originally Posted by
henra
First of all: I can largely follow your Maths. In a straight line the PAPI is a bit less than1550m from the Eastern bank of the Potomac on a straight 328° course. At 3° this would be 270ft altitude when crossing the -east bank. Both aircraft ended up in the Potomac. When looking at the point of impact of the Blackhawk in the Potomac in these videos I end up with a spot ~1450m from the PAPI.
On the other hand the collision will have somewhat altered trajectory of both aircraft, so maybe the collision had still occured over land and due to the lateral energy transfer the Helicopter was thrown off its original course towards the West and into the river. We will get this information finally.
And in the end it doesn't really make that much of a difference wrt the level of lunacy of this whole setup.
I think the collision was closer to 1250m (4100') from the PAPI. I base that upon the NTSB statement "
At 8:47:58, the crew had a verbal reaction, and FDR (flight data recorder) data showed the airplane beginning to increase its pitch. Sounds of impact were audible about one second later," That puts the collision at about 8:47:59 (01:47:59Z). ADS-B Exchange data at that time puts the ground distance to the PAPI between 1200-1280m (3900-4200'). My assumptions are that the NTSB statement is correct and that the ADS-B Exchange data is accurate (which in my experience, the times are generally less than 0.2 seconds later than the timestamps on data collected by the FAA, and the reported NACp (position accuracy) was estimated at < 10m). Here is the graphical representation I generated of my estimated collision position vs. PAPI.
Collision Altitude vs PAPI
Originally Posted by
galaxy flyer
Having been in a mid-air collision with similar geometry, I would bet it was only normal input to approach path. FDR’s are incredibly sensitive recorders. I have a vague memory of the other plane’s wing flashing by. It looks slow in the videos, but it’s incredibly fast.
If my depiction is accurate, it's hard to see why they would pitch up as normal input to approach path. I think their inputs would have been focused on getting down.