Very nice work, takata.
I was unaware of the SHOM PowerPoint and had not seen the last known position coordinates in print before - thanks. I have spent a bit of time re-plotting the BEA reconstructed flight path, and it is reassuring that the locations derived from reverse engineering the BEA flight path points in Google Earth are a good match for the GPS coordinates obtained from the ACARS 0210Z position report. My earlier analysis is in the Tim Vasquez forum:
Jet Crash forum • View topic - Crash location
The BEA flight path points are labeled to the second (e.g. 02:00:00, probably the GPS time stamp), so that by reproducing the coordinates of the points in Google Earth by moving them around until they are a good match for details in the sea floor bathymetry in BEA plot it is possible to calculate speed and distance covered. Here is the result:
0120Z - 2° 48.000'S, 33° 35.000'W
77.0 nm, 462 kt
0130Z - 1° 39.500'S, 32° 59.000'W
78.9 nm, 473 kt
0140Z - 0° 29.421'S, 32° 22.002'W
78.0 nm, 468 kt
0150Z - 0° 39.943'N, 31° 45.392'W
77.4 nm, 464 kt
0200Z - 1° 48.654'N, 31° 9.109'W
77.2 nm, 463 kt
0210Z - last known position - 2° 58.700'N, 30° 35.800'W
This last known position derived independently by reverse engineering the BEA plot is 2.978°N, 30.597°W in decimal degrees, a very close match to the location published by SHOM of 2.98°N, 30.59° W, which gives me some confidence in the others. Incidentally, this position is also a good match for the last reported position plotted on one of the actual FAB SAR maps (the red airplane symbol) used by the search teams, as I posted earlier:
http://www.pprune.org/rumours-news/3...ml#post4982877
Variation in the locations, and therefore the speeds and distances, could well be due to small errors in reproducing the BEA flight path positions in Google Earth. It will be interesting to see how close these are to the actual GPS coordinates that hopefully will be in the BEA accident report. The calculated speed between 0120Z and 0140Z is 468 kt, a match for the ground speed of 467 kt calculated by Barry Carlson from the flight plan speed of Mach 0.82:
Final Route of AF447 - an Analysis
One key result of my analysis is that there evidently was no change in speed prior to 0210Z.
Much of takata's analysis concerns the speed and direction of the drifting debris. There are actually some data on drift in this area that cover the period 1 June to 6 June from oceanographic drifting buoys, although they are not all that close to the last known position. Buoy 31919 NE of TASIL drifted 46 nm to the WSW during this period, and Buoy 31256 SE of TASIL drifted 64 nm to the NE. These are more or less in opposite directions, so I suspect the actual drift of the debris during this period was complex.
Attachments do not seem to be enabled, or I would post a map of the flight path and drifter buoy paths. You can view it in the Sun Jun 21, 2009 6:53 pm post at:
Jet Crash forum • View topic - Crash location
-rer47