Yesterday the “Independent Group” (IG) of technical experts looking into the disappearance of Malaysia Airlines flight 370 (of which I am a part) released a new report which made the case that the official search area now being scoured by undersea robots is not where the plane most likely crashed. The reason, the group explained, is that the Australian Transport and Safety Board has relied on a statistical model in which hundreds of possible paths were generated, then winnowed down to include only those that fit the timing and frequency data from the seven handshake pings; this resulted in a distribution whose greatest density coincides with the current search area. The Independent Group, in contrast, began by asking what possible routes most closely match the flight speeds and altitudes that a pilot would most likely choose:
The ATSB analysis used two basic analysis techniques referred to as “Data Driven” and “Flight path/mode driven”… While we agree that these statistical methods are reasonable techniques, both tend to overlook or minimize likely human factors in favor of pure mathematical statistics. This ATSB approach appears to have resulted in a conclusion that the most likely average speed was approximately 400 kts (Appendix A). However, 400 kts is not consistent with standard operating procedure (typically 35,000 feet and 470-480 kts), nor is it consistent with the likely speed a pilot would choose in a decompression scenario (10,000 feet and 250-300 kts). A speed of 400 kts may minimize the BTO and BFO errors for a given set of assumptions, but the errors can also be shown to be very small for other speeds. Given all the tolerances and uncertainties, we believe it is important to consider human factors with more weight… B777 pilots consistently tell us that under normal conditions, the preferred cruise attitude would be 35,000 feet and the TAS would be approximately 470-480 kts. We believe this is the most likely case for MH370, and note that the last ADS-B data available indicated that MH370 was at 35,000 feet and 471 kts at that time.
As can be seen in the chart above, the differing approaches result in search areas that are some 500 miles apart. The full report can be found online here.
UPDATE 9/12/14: Richard Godfrey has pointed out that a recent report from the ATSB shows that the seabed-mapping effort has recently been extended some 200 nautical miles toward the IG search area: