Category: Aviation

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:

 

 

At a press conference in Canberra today, Australian Deputy Prime Minister Warren Truss state that “further refinement of satellite data” indicated that missing Malaysia Airlines Flight MH370 had turned south earlier than investigators had originally thought. This implied, he said, that the plane had most likely would up further to the south than previously estimated.

The previous assumption was laid out in a report released in June by the Australian Transport Safety Board (ATSB), which included the map shown here. The document described a methodology for determining the search area which suggested that the plane did not make a single turn to the south and then fly on a straight-ahead course into the southern ocean, but rather lingered near western Sumatra for the better part of an hour.

After the report was issued, a loose coalition of experts from around the world called the Independent Group (of which I’m a part) released a statement which questioned the ATSB’s methodology, and in particular pointed out that signal data related to an attempted satellite phone call at 18.40 UTC indicated that the plane was already established on a course to the south. This fact allows the range of possible flight paths to be narrowed considerably.

As fate would have it, Truss’ announcement came just one day after the Independent Group issued a follow-up statement reminding the authorities that its own analysis suggested a search area futher to the south.

“The data is nothing new, but the fact that the Australian government has chosen to issue this statement is very interesting,” says Independent Group member Victor Iannello.

Truss was vague as to where the priority search area had shifted, saying it remained “within the search area” previously laid out in the southern Indian Ocean. This area, however, is more than 1,500 miles long.

It’s been two months since I last posted about MH370, so I think I’m overdue for an update. The big news that’s happened in the meantime is that on June 26th, the Australian Transport Safety Board (ATSB) released a report that laid out in admirable detail what the authorities felt they knew about the circumstance of MH370’s disappearance and how they had come to narrow down its likely location to the current search area. We now have a much clearer understanding of just what Inmarsat’s data reveals about the last four hours of the flight.

In the report, the ATSB explains that sometime after the plane vanished from radar screens at 18:22 GMT, whoever was in control  most likely became incapacitated and the plane flew on autopilot until it ran out of fuel and crashed into the depths of the Indian Ocean some time after 0:19 GMT. Its impact point, according to the ATSB’s calculations, was most likely somewhere in a region 1,000 miles off the coast of Western Australia.

As you’ll notice, that last sentence is extremely vague. The reason is that, as we now understand, the data is incapable of telling where the plane went with any degree of certainty. That is to say, you cannot recreate the airplane’s flight path using Inmarsat data alone. This is kind of a shocker, because for months now, Inmarsat has been telling the public that their mathematical wizardry had allowed them essentially to solve for the plane’s final location. This turns out to be false. For any given flight path, we can now calculate the expected BTO and BFO values; but given a set of BFO and BTO values, we cannot derive a unique flight path.

Take a look at the route chart at the top of this post, which comes from page 31 of the ATSB report. It shows the actual path of a Malaysia Airline jet that flew on the same day at MH370, as well as an “estimated” path generated from the BFO and BTO data recorded from that same airpline. If you’re like me, when you first saw this chart, you assumed that Inmarsat had decoded the BFO and BTO data so thoroughly that they could generate specific flight paths like this one. Give them BFO and BTO data, and they could draw you a line on the map; no wonder they say they know exactly where to spend $56 million scouring the sea bed. But if you read the accompanying text, what it says is: “Using only the starting location and an equivalent number, and approximate time spacing, of BFO and BTO values as the accident flight, predicted paths were created and compared against the actual flight paths.” Reading between the lines, the ATSB was able to generate not just the route illustrated here, but dozens or possibly hundreds, and chose this one as the most promising for MH021.

There’s another disappointing realization embedded in the ATSB report. Continue reading What Could Have Happened to MH370?

A hundred days have passed since MH370 went missing — and while air and sea search operations have been put on hold, hope springs eternal. Today, the BBC is reporting that Inmarsat remains confident that its analysis of the satellite data will lead to the plane, saying that the authorities never searched the area of highest probability because they were distracted by the underwater acoustic pings that turned out not to have come from MH370’s black boxes. Once a new search gets underway, it will explore an area that conforms much better to the likely speed and heading of the missing plane:

By modelling a flight with a constant speed and a constant heading consistent with the plane being flown by autopilot – the team found one flight path that lined up with all its data. “We can identify a path that matches exactly with all those frequency measurements and with the timing measurements and lands on the final arc at a particular location, which then gives us a sort of a hotspot area on the final arc where we believe the most likely area is,” said Mr Ashton.

Unfortunately, it will be several months before such a search of this new area can get underway, since the survey of the ocean floor will be required to figure out how deep it is and what kind of underwater technology should be used. Meanwhile, a spokesman for the Australian organization leading the search described a more complex and ambiguous state of affairs, telling the AFP that experts were still struggling to narrow down the highest-probability search area, taking into consideration not just the satellite data but also “aircraft performance data [and] a range of other information.”

What other information? Your guess is as good as mine. As I wrote last week in Slate, Inmarsat has by now leaked enough clues about MH370’s electronic Inmarsat “handshakes” that outsiders can now understand why, mathematically, the plane must have gone south. Yet we have not the slightest hint of what sequence of events might have taken it there. We don’t even know how it could have navigated southward. An airliner like the 777 doesn’t just wing off in random directions like a paper airplane; its Flight Management System would have been following a series of waypoints or a compass heading. Yet its range of possible courses doesn’t seem to match up with any particular heading or waypoint. (The last search area matched up with a flight route that tracked waypoints between the Cocos Islands and Australia, which is likely one of the reasons it seemed so appealing to authorities, but as we now know, that came up empty.)

MH370 looks to be a unique case not just in aviation history. No machine this big, no group of human beings this large, vanished so completely and so mysteriously since the advent of modern technology. What’s more, MH370 didn’t just disappear once, but three times.

The first disappearance, of course, was when it vanished from air traffic controllers’ screens in the early morning hours of March 8, apparently after someone turned off its transponder and automatic status-reporting equipment, and took a hard left turn. Based on the speed and precision of its navigation, the plane almost certainly was under human control.

The second disappearance occurred about an hour later, as the plane slipped beyond the range of military radar. Minutes later, some kind of unknown event caused the plane to transmit a mysterious triple burst of electronic signals to the Inmarsat satellite. At around the same time, the plane took another radical course change, pivoting from a northwest heading toward mainland Asia to a southwestern course that would take it over western Indonesia and out into the open ocean. Based on the slim evidence of subsequent Inmarsat pings, the plane seems to have flown in a simple straight line, so it may not have been under human control at that point.

Then it disappeared a third and final time, this time leaving not a single clue. Continue reading The Triple-Disappearing Airplane

Two weeks ago, after months of mounting public pressure, Inmarsat and the Malaysian government finally released the raw satellite data that had been received from the missing Malaysia Airlines Flight 370. Most of the data dump proved unrevealing. But tucked away amid 47 pages of detailed communications logs and explanatory notes was a two-sentence description of the plane’s electronics system that turned out to be a doozy. Combined with previously released data, publicly available information, and a little vector mathematics, it has proved sufficient to lift the veil on Inmarsat’s calculations and reveal the ultimate fate of the plane.

The story goes back to March 25, when Malaysian authorities announced that an analysis of the data had determined that the plane must have wound up in the southern Indian Ocean. An explanatory document released at the time purported to back up that claim with charts and numbers, but as I’ve written earlier, it in fact was so obtuse that it didn’t really clarify anything at all. The message’s subtext was basically: Trust us, we know what we’re doing. But the subsequent behavior of the search officials—who, among other things, promised that they’d located the plane underwater but then came up empty-handed—left little room for confidence. Many, including me, wondered whether the authorities were hiding something, or else trying to conceal how little they knew. Continue reading Slate: Where the Missing Plane Went

UPDATE 5/21/14: The families of missing MH370 passengers have released a fascinating document presenting their own analysis of the preliminary report issued by the Malaysian government’s Ministry of Transport, including their own assessment of what we know and what we’d like to know. Link: Analysis of the Preliminary Report on MH370 Incident, May 20 2014

by Michael Exner

[Note: The totality of what we know about the fate of missing Malaysia Airlines Flight 370 consists of a series of electronic handshake “pings” that were received by an Inmarsat satellite in the hours before the plane disappeared for good. Unfortunately, the authorities have steadfastly refused to release the full data set to the public, and there is an ongoing dispute between Inmarsat and Malaysia as to who exactly has the data and who is authorized to release it. According to CNN, a source within Inmarsat has said that the company released satellite ping data amounting to just 14 numbers to Malaysian authorities, along with documentation explaining their methods for analyzing the data. Here Michael Exner, Chairman of the Board of Radiometrics Corporation, weights in on that claim. — Jeff Wise]

In fact, we know there are at least 51 numbers, and here’s why. The BFO chart [released on March 25 by the Malaysian government as page two of “Annex I” accompanying the Inmarsat report — ed] shows 12 times and 12 frequencies. That’s 24 numbers.

Then, on April 29, there was a photo in Beijing that showed that there were more handshakes, and ACARS messages that preceded the first handshake on the BFO chart, but there were no BFO values given in the Beijing meeting with the families. But the fact that they had the angles proves they had the times and the BFO values. Thus, we know of at least 17 events for which they have Time, BFO and Angle (or time delays). That is 51 numbers total.

We have assembled the following data from two sources. The “BFO Data” provided in the March 25th AAIB ANNEX I Chart and the photo taken in Beijing on April 29, 2014.

Note that the numbers above represent our best estimates based on digitized paper graphs and photos. The true resolution is less than that inferred by the number of digits. Apparently, the statements about “…only 14 numbers…” are in reference to the last 7 BFO frequencies and last 7 elevation angles, which the official investigation team is focused on. But all the data from the other events are also valuable for the calibration of the other data. Those first 10 events are also very important. Continue reading Guest Post: What We Know About MH370, and What We Would Like to Know

This is happening late at night and will bear further discussion in the morning, but I wanted to get something up online quickly to explain the basic gist of the situation. A little over an hour ago, at 9.30pm EDT here in the US, the Australian government announced that it was abandoning the current search area and moving to a new one 11oo km to the northeast. The reason, they said, is:

The search area for missing Malaysia Airlines flight MH370 has been updated after a new credible lead was provided to the Australian Maritime Safety Authority (AMSA)… The new information is based on continuing analysis of radar data between the South China Sea and the Strait of Malacca before radar contact was lost. It indicated that the aircraft was travelling faster than previously estimated, resulting in increased fuel usage and reducing the possible distance the aircraft travelled south into the Indian Ocean.

This explanation really doesn’t make any sense. I want to quickly explain why, and give some context of where all this is happening geographically.

First, here’s a very crude chart I’ve made on Google Earth showing  the old search area and the new search area (very roughly estimated). You’ll recall that earlier this week Inmarsat released an analysis of its “ping” data that plotted different routes the aircraft might have taken. The upshot was that if the plane was flying at 450 knots, it would have wound up at a spot on the 8.11am ping arc marked “450.” If it had flown at 400 knots, it would have wound up around the spot marked “400.” (click to enlarge)

 

As you can see, it appears that the old search area assumed a flying speed of a bit more than 450 knots, and the new search area assumes a flying speed of a bit more than 400 knots, with prevailing currents causing debris to drift to the southeast.

The shifting of the search area to the northeast would seem to stand at odds with the assertion of the press release, which implies that new radar analysis finds the plane was flying faster then originally estimated. In fact, it was flying slower than originally estimated.

At any rate, the abandoning of the old search area, after such significant assets had been lavished upon it, raises the question of why they were so confident about it that speed estimate in the first place. And then raises the obvious sequela: Why are they so confident in this one?

BTW, here’s that graphic from the Inmarsat, showing the 450 and 400 knot plots:

UPDATED: See end for description of possible northern route

On Saturday, March 15, Malaysian authorities released an analysis of satellite data that dramatically narrowed the possibilities for where missing Malaysia Airlines Flight 370 had gone after it disappeared from radar on March 8. Over the course of the following week, Inmarsat released further information that not only showed where the plane went, but also indicated how it got there. The results are shown on this chart. We still don’t know if the plane headed north or south, but if it went north, it made landfall near the western India-Bangladesh border and proceeded along the Himalayas to Central Asia. If it went south, it passed over western Indonesia and out over the southern Indian Ocean.

How are we able to determine this? The procedure requires a bit of explanation. Continue reading The Path of the Missing Malaysian Airliner: What We Know, and How — UPDATED