Originally Posted by
WideScreen
Let me drop in some remarks, just based on the adsbexchange path/altitude diagram:
All altitudes/heights in WGS84 GPS measures, which seem to be 200-350 ft higher than the baro altitude (the P-51 and P-63 seem to differ with this with 150 ft, maybe somebody can report the WGS84 height of Dallas Executive Airport ?).
My notes:
- Before the climb to the turning point, the P-63 approaches the P-51 at 1800 ft with less than 50 ft altitude difference, with maybe 300 ft separation distance at 170kts. Challenging, do-able, though probably outside the allowed display limits, especially in a climbing/descending/turning situation.
- The P-63 initially takes evading action to "dive" and immediately reverts to a 1500 ft/min climb. Since the P-51 does do the same, the P-63 continuous evading action by increasing the climb rate to 2500 ft/min. The P-63 also widens the turn, evading the P-51 laterally.
- When the P-51 already turns towards the display line and starts descending, the P-63 keeps climbing and moving away from the display line entry point.
- The P-51 shows a civil & steady -640 ft/min decent rate.
- The P-63 goes in 11 seconds from a +2500 ft/min to (sustained) -4000 ft/min. An interesting amount of g-forces: Puking, disorienting, negative G's.
- When the P-63 is long into its dive, it seems to set course direct to the display line entry point (vs a more shallow turn, to be nicely parallel with the display line, when passing the display line entry point).
- Even at 1000 ft, the descent rate is still -2600 ft/min. Challenging, with a target altitude for horizontal flight of 700 ft.
- At 900 ft, the course is still direct towards the marker for the display line entry point.
- At 800 ft, the descent rate is still -1800 ft/min. Challenging to end up at 700 ft. It's a fighter, so do-able......
- Then, the P-63 track suddenly starts to change, seemingly in order to get parallel with / not overshoot the display line. Just, as is also visible on the Jason Whitely Twitter video, 1-2 seconds before impact, the P-63 is banking steeply.
Or, so to say, this seems to be a classical case of "getting behind the airplane". Initially (somewhat) in the climb, evading the P-51 with a significant climb rate (and widening the turn), and subsequently not normalizing the descent rate on the descent, with a disputable track selection to enter the display area. The recovery being potentially and realistically difficult due to the high negative G's at the moment of rounding the top of the climb. The sustained -4000 ft/min decent rate tells a story, you don't do this in a "tame" historic aircraft display situation.
The interesting question for this case is, where would the P-63 have ended up, when the B-17 would not have been there, in the P-63's flight path ?
Given the steep bank, there was little opportunity to stop the -1800 ft/min descent (at 800 ft, with probably 200-350 less effective altitude !). And I highly doubt, given the P-63 and B-17 do have, right before impact, a 30 degrees track difference, whether the P-63 would not have caused a display line overshoot of some 200-300 ft. Combine that with the significant descent rate (probably increasing again, due to the steep bank), and it certainly would have been possible, the P-63 would have impacted the ground in a steep bank, with a 200+ KTS speed, shattered, etc, just around, where the display public would have been located.
And, finally, was the steep bank a B-17 evading action, or was it an attempt to not overshoot the display line ? I would expect the latter one, given a better B-17 evading action would have been to climb (or at least, no further descent, which would have been sufficient). More than enough kinetic energy in the aircraft and pull-up capabilities to do so.
Could it be, there was a mechanical malfunction with the P-63: Of course, though probably not, given the last moment "try to save the beans" bank angle change.