Talk:Crash of Malaysia Airlines flight MH17/Investigation

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See also: Investigations updates (main discussion page); Joint investigation team report announcement, and Almaz-Antey Response to that; and Radar data discussion.

Sources

DSB final report

Radar Data

Discussion of missile, or anything else, non-detection, in the final DSB report is p 114/279

See also: Radar data

Weather

Clouds: p 35/279, final report.

Weather chart, appendix F, 37/176. Unclear what is shown (isobars?) FL means flight level, FL400 means 40,000 feet.

Wind

On the ground, pp 32-33/279 of the final report, under 10 m/s with gusts up to 16 m/s

Forecast given to crew, at FL330-350 (ie height 33,000 to 35,000 ft): 160 to 165 degrees, 17-19 knots (8/10 m/s) before PEKIT waypoint, up to 40 knots (21 m/s) after.

P 111/279: Flight data recorder: time: 13:20:03 UTC. magnetic heading 115 degrees, indicated airspeed 293 knots (150.732 m/s). Wind 219 degrees, 36 knot (18.52 m/s).

Indicated airspeed is read directly from instruments, and does not account for windspeed. Ground speed is obtained as a (vector) sum of airspeed and windspeed, but 293 is not the ground speed, it is rather instrument measured, and it is low at this point (cruise speed would be 494 knots).

Question raised here (how come wind is 100 m/s)? A: (1) it appears that wind detailed in the final report is much lower, 19 m/s, and low aircraft speed reading is due to something else, not high winds (airplane crashing may be a factor, but it will take at least few, to over 10 seconds to drop speed by 100 m/s. Speed is usually measured by pitot tube and is pressure sensitive, so it can be affected by the explosion; unfortunately speed vs time signal is not given, only one reading, and acceleration vs time graphs, with no acceleration, apart from g vertically, shown --presumably it shows g at steady flight, shows 0 for a free fall). Winds in low to upper stratosphere are jets, which are not much weather sensitive, and can reach 60-70 m/s. They are assumed geostrophic (due to pressure gradient and Coriolis force), and may be computed from satellite temperature data (similar to here, -a formula based on isobar surface). 100 m/s is not too far off from 60-70 m/s, so it could be in principle, but in reality it appears to be much lower, with nothing too unusual going on. --Resup (talk) 02:41, 28 November 2016 (UTC)

But also on p 47/279 it says that it was moving at a "constant computed speed of 294 knots," with a footnote that groundspeed was 494 knots (below Figure 10), the same up to formatting as in the Titter question taken from preliminary report, below Figure 5 there. Windspeed data (and other flight recorder data) are shown in Appendix H, p 52/176; it is not more than 36 knots. Flight recorder shows essentially no acceleration, and even at 1 g or several g it will take about 10 seconds /few seconds for speed to drop by 100 m/s; so than 'computed speed' was around 294 knots before it was hit. 'Computed speed' is probably the same as 'calibrated airspeed', which is 'indicated airspeed' corrected by known systemic error of the measuring device. So actually it looks like something, most likely speed relative to air, was not computed correctly. Groundspeed can be measured by radars or GPS, and should be quite accurate, but after crash it could be interpolated, not measured data.

Appendix H (p 50/176 of appendices) also show microphone recordings. Two peaks are recorded by one of microphones (why 2? pressure shock wave and fragments arriving ?); also a signal prior to that on pilots microphones (what's that? started to shout before it hit?). It sucks that UTC time of microphone data is not spelled out exactly to locate this time on other flight recordings, but presumably it is a 40 millisecond window of 13:20:03 UTC, and everything else has no peaks and just ends (?) --Resup (talk) 06:18, 28 November 2016 (UTC)

ATC Transcript

Appendix G, p 38/176 of appendices. Includes brief conversation between Rostov and Dnepropetrovsk ATC, on redirecting to RND waypoint due to congestion; followed by long exchange trying to locate after plane disappeared.