We Now Have Confirmed Ping Rings
Duncan Steel, 2014 April 29.
duncansteel.com
Many times I have bewailed the fact that the ping ring sizes (apart from the final ping ring at 00:11 UTC) have been kept secret by the influence of unknown parties. It now seems that they have been released (more than seven weeks after the loss of the aircraft).
A correspondent named Nathan has sent in a comment regarding a CNN Twitter feed here that apparently shows a (rather fuzzy) graph of the elevation angles for the satellite pings of MH370, issued a few hours ago by the Malaysian Government. I am assuming that this is a valid piece of information, and expect it to be confirmed by later reports and posts on the relevant Malaysian Government website.
Here is the graph in question:
Obviously that image of the graph is difficult to read, but I think that I have managed to work out the values plotted with reasonable accuracy. The elevation angles I obtained are as in the following table. Using those elevation angles I then calculated radii for ping rings as shown in the final column in the table. Note that these are indeed ‘radii’ in that I have calculated here their sizes according to the method described in a previous post. That is, these are not ‘non-circular ping rings’ taking into account the non-sphericity of the Earth and therefore a radius changing with latitude, but instead I have simply calculated a uniform ring radius based on the aircraft-satellite range given the elevation angle and the satellite’s ephemeris (altitude, and the latitude of the sub-satellite point, the aircraft being taken to be at the same latitude in this simplified geometry).
These elevation angles and ping ring radii can be compared to those calculated previously on the basis of the back-engineering performed by GlobusMax.
Please anyone and everyone check my values read off that graph, and also check the results of my calculations for the ping ring radii. (Especially as I have jet lag at the moment.)
As soon as I am able I will enter these ping rings into my STK scenario and then make KML files available to all.
| Time UTC | Elevation angle from aircraft to satellite (degrees) | Radius of range ring on Earth’s surface (nautical miles) |
| 16:30 | 46.6 | 2250 |
| 16:43 | 46.5 | 2255 |
| 16:55 | 45.9 | 2287 |
| 17:07 | 45.0 | 2335 |
| 18:29 | 52.2 | 1952 |
| 19:40 | 54.8 | 1815 |
| 20:40 | 54.1 | 1852 |
| 21:40 | 51.6 | 1984 |
| 22:40 | 47.3 | 2212 |
| 00:11 | 40.1 | 2599 |
Bill,
Cheryl #1 here. From your last post when you stated that “the voices pop on and off with imperfect timing, and unnatural sounding ramp up” seems to accurately describe what I think I am hearing regarding just the “patchy” sounds. At times one can almost hear when the transmission from the plane comes in, an audible “distance” as if the sound is truly coming from an object far away. Other times it sounds less distant, with no static, and as if someone was just sitting with a microphone in a room alone close by.
Yap, Henrik,
I am a layman. Victorl has this theory that the SDU was not getting updates from the AIMS after 1.07am. Is it possible that the BFO chart for the 6 pings merely reflects the satellite movement and speed plus a fixed offset? I asked because (a) the BFO values start increasing from 19.40 which is just a few minutes after the satellite had reached its northern apex at 19.36 and began moving southwards at increasing speeds (b) the BFO values for 18.29 and 20.40 are about the same at 140 Hz when the satellite speeds for these 2 times are about the same at roughly 49 knots and (c) if we minus 90Hz from the BFO values, we seem to end up with the satellite speeds for the corresponding times eg at 18.29 BFO is roughly 140, so minus 90 is 50 which is roughly the satellite speed at that time in knots and at 00.11 BFO is 250 so minus 90 is 160 which is roughly the satellite speed in knots at that time and (d) if the plane was not getting updates from AIMS as to its position, speed etc, the Doppler correction could have been calculated based on ‘unprocessed’ or ‘raw’ satellite data ie without reducing those values by Cosine this and Cosine that. Hope this all makes sense.
Alex,
I think a few of our more mathematically inclined contributors are working through how the loss of real time airplane data would affect the BFO. I think there are already a few posts discussing some progress. Check for more information from them.
I am trying to think through how we might ‘remotely diagnose’ what was happening in the plane to cause the various symptoms that we see. If we can understand this apparent disconnect between the satellite subsystem and the other plane subsystems, we might start to identify scenarios somewhere in between ‘the plane broke’, and ‘someone intentionally flew to the farthest possible ocean’ (I made those up…).
If we can understand how and when the flight systems might have been affected, we might get a better handle on how (and where) the plane was flying.
-Bill