Pilot Fighter
Well-Known Member
One more thing from lining up the radio calls with the ADS-B. To my ear, her voice changes significantly between the 10,000 fpm call and the 20,000 fpm call. On the first she's energetic and alert but composed. On the second she sounds much more alarmed, while still having the presence of mind to keep working the radio (using the call sign, for instance). The ADS-B data changes in those same seconds.
Times are UTC and assume the LiveATC archive starts at exactly 17:30:00. Path angle uses ground speed and Mach is rough, with wind unknown and temperature taken from the crew's −47°C report:
- 17:48:30, "Mayday", 10,000 fpm call: −14,016 fpm, path 16° down, no turn (track 099°), about 0.84 Mach.
- 17:48:36, "[Declaring] emergency": −19,904 fpm, path 22° down, first movement in the track, about 0.88 Mach.
- 17:48:41, 20,000 fpm call: about −20,700 fpm, path 22–23° down, turning right at 1.2°/s, about 0.90 Mach.
- 17:48:50: −20,864 fpm, path 22° down, turning right at 2.5°/s, about 0.90 Mach.
- 17:49:03, "twenty two thousand feet ... banking sixty": over −31,000 fpm, path about 35–40° down, turning right at 2–4°/s, about 0.91 Mach.
The jet appears to go over its Mach limit at about the time of the first descent and Mayday calls. Mmo is 0.81 Mach from 26,750 to 37,000 ft (Learjet 60 AFM FM-123, Change 37, page 1-9, a 2009 revision; the FAA data sheet charts the same limit, TCDS A10CE, Rev. 67, page 23: Dynamic Regulatory System ). Assuming no wind, it passes 0.81 at about 17:48:27, about when she first calls the descent. Assuming 20 kt of headwind or tailwind moves that to about 17:48:21 or 17:48:32, still after the descent began at about 17:48:16.
The right turn first shows at about 17:48:36, about when she starts to sound more alarmed, within about a second of alignment. Before that the jet is presumably in a wings-level nose-over, with load well under 1 g (our rough estimates run about 0.1–0.4 g). After it, the bank is building at about 1.1–1.4 g, and the speed is near 0.90 Mach. Those load figures are estimates from fitted ADS-B, not measurements.
The descent rate climbs fast until about 17:48:36, then holds near 20,000 fpm until about 17:48:50 before steepening again. Her 20,000 call falls on that plateau and that number matches the ADS-B data.
What this doesn't show is what caused the change in her voice from call to call. She could be reacting to the overspeed, the rate, the roll, or recovery inputs that weren't working. It's tempting, but obviously still premature, to tie the start of the bank to the left elevator coming off, since the NTSB says most of it was found 1.3 to 3.8 miles from the site. A separation at that moment would need about 2 miles of drift or carry, which is possible, but nothing shows it. Also, of course, a right spiral isn't necessarily due to a left elevator separation. High-Mach wing drop, uneven ice or damage, or a small roll that a pull then tightens could all do it.
Same caveats as before: a rough outline, not a forensic analysis. Still using well-managed AI assistance; numbers and calculations are checkable against public data.
Pete
Are you under the impression that you’ve provided new insights?
Once this plane turned into a
One more thing from lining up the radio calls with the ADS-B. To my ear, her voice changes significantly between the 10,000 fpm call and the 20,000 fpm call. On the first she's energetic and alert but composed. On the second she sounds much more alarmed, while still having the presence of mind to keep working the radio (using the call sign, for instance). The ADS-B data changes in those same seconds.
Times are UTC and assume the LiveATC archive starts at exactly 17:30:00. Path angle uses ground speed and Mach is rough, with wind unknown and temperature taken from the crew's −47°C report:
- 17:48:30, "Mayday", 10,000 fpm call: −14,016 fpm, path 16° down, no turn (track 099°), about 0.84 Mach.
- 17:48:36, "[Declaring] emergency": −19,904 fpm, path 22° down, first movement in the track, about 0.88 Mach.
- 17:48:41, 20,000 fpm call: about −20,700 fpm, path 22–23° down, turning right at 1.2°/s, about 0.90 Mach.
- 17:48:50: −20,864 fpm, path 22° down, turning right at 2.5°/s, about 0.90 Mach.
- 17:49:03, "twenty two thousand feet ... banking sixty": over −31,000 fpm, path about 35–40° down, turning right at 2–4°/s, about 0.91 Mach.
The jet appears to go over its Mach limit at about the time of the first descent and Mayday calls. Mmo is 0.81 Mach from 26,750 to 37,000 ft (Learjet 60 AFM FM-123, Change 37, page 1-9, a 2009 revision; the FAA data sheet charts the same limit, TCDS A10CE, Rev. 67, page 23: Dynamic Regulatory System ). Assuming no wind, it passes 0.81 at about 17:48:27, about when she first calls the descent. Assuming 20 kt of headwind or tailwind moves that to about 17:48:21 or 17:48:32, still after the descent began at about 17:48:16.
The right turn first shows at about 17:48:36, about when she starts to sound more alarmed, within about a second of alignment. Before that the jet is presumably in a wings-level nose-over, with load well under 1 g (our rough estimates run about 0.1–0.4 g). After it, the bank is building at about 1.1–1.4 g, and the speed is near 0.90 Mach. Those load figures are estimates from fitted ADS-B, not measurements.
The descent rate climbs fast until about 17:48:36, then holds near 20,000 fpm until about 17:48:50 before steepening again. Her 20,000 call falls on that plateau and that number matches the ADS-B data.
What this doesn't show is what caused the change in her voice from call to call. She could be reacting to the overspeed, the rate, the roll, or recovery inputs that weren't working. It's tempting, but obviously still premature, to tie the start of the bank to the left elevator coming off, since the NTSB says most of it was found 1.3 to 3.8 miles from the site. A separation at that moment would need about 2 miles of drift or carry, which is possible, but nothing shows it. Also, of course, a right spiral isn't necessarily due to a left elevator separation. High-Mach wing drop, uneven ice or damage, or a small roll that a pull then tightens could all do it.
Same caveats as before: a rough outline, not a forensic analysis. Still using well-managed AI assistance; numbers and calculations are checkable against public data.
Pete
You haven’t added anything to the conversation.
Cheesus Crust, now dr phil has a youtube video that showed up in my right column.
