DSB doubts: mistake in wind speed graph label
DSB presented in Appendix K a calculation to calculate the ballistic trajectory of MH17 debris. The ballistic trajectory assists in the break-up sequence analysis.
The trajectory is a complex formula in which many parameters are used. One of them the winddirection and speed.
DSB states that data from a weather balloon measurements from Rostov on Don was used as input for trajectory calculations.
The image below is shown at page 75 in the DSB report. The report does not state the time the weather ballon reported windspeed and winddirection.
We see the windspeed reported in Knots (kts). 10 knots is 5.14444 meters/second.
Rostov on Don weather report can be seen here. The weather reports shown on this page are of 00:00 UTC and 12:0 UTC.
This graph (credits mh17.webtlk.ru) shows the DSB graph on the left and the Rostov on Don data on the right.
I took the 12:00 UTC data and copied it in OfficeOffice spreadsheet program to create the same graphs. Goal is to confirm DSB used the 12:00 UTC data of Rostov.
As you can see, the two graphs are exactly the same as the DSB graphs. So this makes it highly likely DSB took the 12:00 UTC data.
However, the reported speed by the Rostov on Don weather balloon was in meters per second.
For example. the windspeed at 5000 feet was 11 m/s according Rostov weather data.
The DSB graph however shows 10/11 knots at 5000 feet. That is just a bit more than 5 m/s, half of the actual windspeed.
Another direct proof the label should be meters/second is the reported wind speed and direction as stored on the Flight Data Recorder. DSB report clearly states the wind speed was 36 knots from direction 219. 36 knots is 18,5 meters/second. MH17 flew on 33.000 (FL330) feet the time of the crash.
We do not know if DSB used the value of knots in their calculation or if this was just a mistake in the graph label text.
DSB response
I contacted the spokeswoman of DSB and asked if DSB agrees the label of the graph shows the wrong text. DSB responded saying the data shown in the graph is a blend of sources like the FDR and weatherballoon measurements. DSB did not state the figure was incorrect so I assume DSB is of the opinion the figure should read knots. Which is obviously wrong. When I requested DSB to elaborate DSB stated they could not tell me more than what has been written in the final report.
They give the correct speed on page 74 of Appendix K (not Appendix X):
“The last recorded wind on the Flight Data Recorder was 219 degrees at 36 knots.”
The graph on Figure 17 on the next page (shown above by Admin) shows the wind speed at the 777’s altitude of 32,000 ft. That speed is clearly less than 20, so it must be in m/s (36 knots = 18.5 m/s).
The only other figure for wind speed that I found was on p.17 of the preliminary report:
“The reported wind at FL320 was from 166 degrees at 13 kts.”
This figure is completely wrong, whether in knots or m/s. The wind direction is off by 53 degrees as well.
The final FDR readings for both the speed and direction of the wind are very close to those from Rostov at that altitude. This suggests that the Rostov readings are a close match to the wind conditions around the crash site at other altitudes as well.
Working on a blog post which exactly shows that.
Brendan:
Also from the DSB report page 34:
“The forecast wind…in Ukraine at FL330 and FL350, as reported to the flight crew in the information provided by the ground handling agent prior to the flight, varied…between 180 and 220 degrees/20 to 40 knots between
air navigation waypoint PEKIT and the border with the Russian Federation at air navigation waypoint TAMAK.”
That range of forecast figures match the FDR figures that you quoted from appendix K.
It’s not mistake. It’s deliberate fake from DSB’s investigators to combine BUK report with Aleynikov’s photos EXIF. If you get Aleynikov data and calculate wind speed — you will get 5,5 m/s — like DSB report at same altitude.
:
Can you explain that? Depending on the distance of the white missile smoke plume, a speed of minimum 8,9 meters/second is calculated.
I can’t explain it on english well (too complex for me). You can read some russian text on that forum’s post: http://mh17.webtalk.ru/viewtopic.php?id=330&p=6#p39375
Well, Aleynikov’s exif data affects on BUKs fire time, missle and mh17 explosions, mh17 fall time (in other words: calc events timeline and see, can it be Snizhne’s BUK or can not).
Some people suggest what old Aleynikov’s exif data was faked – because wind calculation from Aleynikov’s photos show up wrong wind speed (5-6-8 m/s), but wind calc from another media sources (5 sources and models from different authors) show up 10-11 m/s.
On mean wind calculation : http://www.flymeteo.org/stat/sredniy_veter.php
Considering the relatively small time-frame here one has to allow for gusts influencing distance estimates (e.g 2x-3x average over one or several 10-20s periods). Perhaps a probability distribution? Average numbers need at least some margin to work with unless we look at a whole hour or wind.
Figure 10 in Appendix H on p.52 contains a graph of the wind speed over the last three minutes of the flight. That shows a final reading of 36 knots as well. Also shown is a graph of wind direction (in blue) where the final reading is 219 degrees, the same as stated in Appendix K.
The wind speed changed quite a lot in those last three minutes. About 13:17:20 it was only 20 knots. Wind direction was different at that time as well, about 200 degrees, off by 19 degrees compared to the final reading. This means that the readings at that altitude varied quite a lot over a fairly small distance.
Above Rostov on Don at 12:00 UTC, the wind speed was increasing fairly rapidly with altitude at around 10,000 m (from 15 m/s at 9530 m to 28m/s at 10317 m).
So wind speed varied quite a lot with both location and altitude around where MH17 crashed. What I pointed out above about the close match between the Rostov and final FDR readings is therefore probably just a coincidence.
The wind speed graph is in m/s, not knots.
I repeated the ballistics calculation as described in app. K for the cockpit section using wind data from Rostov (time: 12 UTC, 15 local). When I used the wind speed in knots the cockpit didn’t crash in the right place but much closer to a straight line (less wind). When I used m/s the cockpit crashed in the correct position.
So my conclusion is that the wind speed graph is in m/s. That DSB will not admit it or issue an erratum is strange. Maybe to do with the ‘final’ status of the report.