Ref: Steve Winter’s report at:
Analysis: MH370 Preliminary Report | Air Traffic Management | Air Traffic Management - ATM and CMS Industry online, the latest air traffic control industry, CAA, ANSP, SESAR and NEXTGEN news, events, supplier directory and magazine
It’s not my job to act as cheerleader for the analysis we have from the International Panel but Steve Winter has raised some points that I believe can be understood on the basis of the published data, so I offer the following comments:
I have edited the extracts of the report for length.
The first satellite “ping” occurred only five minutes after the last air defence radar contact at 02:22 MYT, so the estimated satellite position is quite tightly constrained….On the basis of the presented information, it seems much more likely that the aircraft would have continued on its heading and that the initial satellite point should be located further south … skewing the entire estimate satellite trajectory (and thus any impact point) by a number of miles.
I was also surprised that the turning point could be so tightly defined on the basis of the data to hand; as plotted it may reflect a best fit to all the ping-arc data, with the North/South constraint of the 18.30 ping-arcs. However, as I have proposed in previous posts, it is the value of 00:11 BFO that sets the final red-zone search area along the 00:11 ping-arc, not the overall course/speed from the ping arc data (at least in the case of level flight at 00:11). The 00:11 BFO has a latitude dependence via component D2.
The maps also show the probability areas for the aircraft impact, corresponding with the final “ping” at 08:19 MYT. The areas are shown as the “Highest Probability Area” to the north, centred on the Zenith Plateau which was the focus of the initial underwater search; the “Lowest Probability Area” to the south of that, and finally, the “Mid Probability Area” to the south of that. This seems curious, as a simple probability distribution would be expected to have the “Mid Probability Area” adjacent to the “Highest Probability Area”. Perhaps this is a typo, but it also makes one wonder why there is no probability area to the north of the Highest Probability Area.
Again as I have proposed before, the high-probability area is set on the basis the aircraft was level at 30000ft at 00:11 so there was no effect of descent rate on the BFO. The width of this zone is set by the total statistical uncertainty. The maps show different heights for the three probability areas, the writer seems to have missed this.
There is no marked area to the North of the red-zone as any climb from 30000ft at 00:11 was regarded as improbable (climb shifts the area North).
This all indicates that further refinement of the satellite data would be useful and that the final resting place of MH370 may well be within a much wider search area.
Further thought since the last post on the differentiation of the red/green/yellow zones. If a descent is allowed as an option at 00:11, then the final BFO value loses most of its value for setting the speed (and hence course) – the mixture of position and descent contributions cannot be disentangled in one measurement. If there was any BFO measurement from the 00:19 partial pings they would be similarly affected as the aircraft would be descending steeply, since 00:19 is generally attributed as the fuel exhaustion point.
With the 00:11 point discounted for this purpose, the selection of the speed/course drops back to the earlier ping-BFO values. The mid-probability/green area may reflect the best fit to these data points only. With a speed/course selected on this basis the 00:11 ping then gives a predicted descent rate. However, the earlier BFO data must have lower value in setting the speed/course in this situation so the predicted area of search might get quite wide (and more so if the initial turning point is not pinned down accurately). The aircraft analysis based on possible autopilot modes/aircraft configuration may constrain the possible descent rates at 00:11 and so still provide some limit in the Southern direction particularly (which corresponds to higher descent speeds).