Today I’d like to discuss some of the implications of what DSTG scientist Neil Gordon said in the course of the interview I published yesterday.
In particular, I’d like to look at what he told me about the ATSB’s interpretation of the 0:19:37 BFO value. Essentially, Gordon assures us that the experts have looked at what the manufacturers know about how these boxes work, and the only interpretation they can come up with is that the BFO value was the result of a very steep rate of descent–specifically, 5,000 fpm at 00:19:29 and then 12,000 to 20,000 fpm at 00:19:37. This is got a gentle deterioration; it’s accelerating at about 1/2 g, so that in another 8 seconds, at that rate, the descent will be at 19,000 to 35,000 fpm, that is to say going straight down at 187 to 345 knots. Remember that the plane had already been losing speed and altitude for five to fifteen minutes before the second engine even flamed out, and losing more altitude in the subsequent two minutes before the 00:19:29 ping was logged. Thus, both velocity and acceleration point to a situation in which the plane will be hitting the surface in short order. Bearing in mind that the plane would be in a spiral dive if unpiloted, I can’t see how it could have traveled more than 5 nm from the last ping, let alone 15nm, let alone 40 nm. It would have hit soon, and it would have hit hard.
One possible explanation would be the idea that the plane was in a phugoid: plunging quickly, then rising again, then plunging again. But as I wrote in a previous post, simulator runs by Mike Exner suggest that these extreme rates of descent are characteristic of the later stages of an unpiloted post-flameout plunge, when phugoid effects are overwhelmed. Thus, if the ATSB is correct in interpreting the final BFO value as a very steep plunge–as Gordon assures us they must–then the plane should be well within 15 nautical miles of the seventh arc.
The chart above (based on the invaluable work of Richard Cole) shows a band of seabed, marked in red, defined by an outer border that is 15 nm beyond the 7th arc and an inner border that is 15 within the 7th arc. As you can see, this band has almost entirely been searched out to the 99% confidence level as defined in Figure 2 of my previous post (located at the intersection of the 7th arc and 94.85 degrees east). All that remains is a rectangle approximately 17 km wide and 150 km long, for a total area of 2,550 sq km.
According to Figure 3 in that same post, the DST calculates that the probability that the plane crossed the seventh arc northeastward of 96.75 degrees east longitude is effectively zero. To search to this longitude would require covering another 3,700 or so sq km. Thus, to cover all the seabed that MH370 could plausibly have reached, if the ATSB’s BTO and BFO analysis is correct, would require another 6,250 sq km of seabed scanning, which is more or less what the ATSB has been planning to search anyway. Unfortunately, the search at present is not taking place in either of these remaining areas.
As I see it, there are four possibilities at this juncture:
- Both the BFO and the BTO analysis are correct, and the plane is lying somewhere in the remaining 6,250 sq km described above.
- The BTO analysis is correct, but the BFO analysis is wrong. In this case, the plane was not necessarily descending with great rapidity, and instead might have been held in a glide, and is most likely in “Area 1” shown above.
- The BTO analysis is incorrect, and the BFO analysis is correct. The plane was indeed descending very rapidly during the last ping, but the plane was further to the northeast somewhere in “Area 2.”
- Both BTO and BFO analysis are incorrect. The plane could be just about anywhere.
I happen to believe that the DSTG knows what it is doing, and that 2 through 4 are not the case. On the other hand, the unsearched areas remaining are at the far fringes of likelihood, and so don’t feel that #1 is a high-probability option, either. No doubt some will argue that the plane might have been overlooked within the area already searched, despite assurances from officials that if it was there they would have seen it.
Frankly, we’re running out of compelling options.