Aviation Archive


MH370: Anatomy of the SIO Search

Here’s a video that niftily recapitulates 15 months of search activity into two minutes. It was produced by commenter @orion, aka Dustin Thomas.

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Where Do We Think MH370 Went?

MH370 poll

Survey conducted by @Jay (Joel Kaye) via the comments section of “Guest Post: Northern Routes and Burst Frequency Offset for MH370.”


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Guest Post: The Backward Method for Finding MH370

by Sabine Lechtenfeld

Note: On the comment thread for “Northern Routes and Burst Frequency Offset for MH370″ last week Sabine (posting under the handle @littlefoot) made a very cogent observation about the use of speculative scenarios in cases like the disappearance of MH370. She’s given me permission to reprint it here.  — JW

Note #2: Language of paragraph 3 modified per Sabine’s request –JW

Getting into a potential perp’s (or group of perps’) mind is a very worthwhile exercise. And that approach has been sorely lacking in the official search. One can argue that this is not their business; it’s the criminal investigation’s job. But even if we would have an ounce of trust in the handling of the case by the Malaysian authorities (I don’t), this argument is very flawed.

Most people agree by now that we’re looking at a crime rather than an accident or disaster (although some argue it might’ve been a combination of both: a hijack gone wrong which leads to a runaway plane).

If the evidence gathered in a preliminary investigation leads to a criminal investigation, a competent handling demands the construction of several possible scenarios featuring plausible perps who might’ve had a valid motive. The next question is how those perps could have tried to achieve their goals. Then you can revisit the available data (radar tracks, handshakes, performance limits, fuel supply, credible eyewitness accounts if there are any) and try to determine if there are any scenarios which fit the known data. If there are no plausible scenarios which fit the available data then you have to question the validity of those data. Fuel-and performance-limits are pretty unassailable. Radar tracks are already in a weaker category and need to be carefully looked at. And Victor and others have shown that the sat data most likely can be manipulated–which doesn’t mean of course that it actually happened. But such a scenario needs to be checked.

The current search has it mostly backwards. The available data were used to determine where it was physically possible for the plane to come down. That was combined with a few assumptions which are very debatable: the plane was flown solely by autopilot and came finally down because the fuel ran out. The question of who were the perps, what could’ve been their motives and how would they most likely have tried to achieve their goals was totally left out, thus leading to an impossibly large search area. And this area isn’t even especially compatible with any logical scenarios. Nor was it ever backed up by a scrap of physical evidence.

In this sense the investigation was indeed deeply flawed to begin with. I don’t blame the investigators that they had a preference for a Southern scenario–the sat data seemed to hint into that direction. But their “destination-SIO-with-autopilot-at-cruising-speed/height-terminated-by-fuel-exhaustion” scenario doesn’t make sense if we assume this was an accident. And it doesn’t make a lot of sense if we assume that we’re dealing with a crime.

The backward method–the place where the plane came down will eventually lead us to the wreckage which will then tell us what actually happened–is only practical if there is enough physical evidence to lead the investigators to a relatively narrow area of impact. As the sole approach it simply doesn’t work with MH370. There isn’t even enough evidence that the plane really crashed. Even the satellite data taken at face value only allow that conclusion if coupled with a set of unproven assumptions. So far the physical evidence doesn’t support these assumptions: no ELT signals, no wreckage and not a scrap of drifting debris after more than a year of searching in the designated areas.

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Guest Post: Northern Routes and Burst Frequency Offset for MH370

by Victor Iannello

Note: Ever since the idea of spoofing was first discussed, one of the main issues has been how falsified BFO values might have been calculated. Most of assumed that the values were arbitrarily selected to suggest a flight in a generally southward direction. Here, Victor Iannello presents an ingenious suggestion: that hijackers might have altered a single parameter in the Satellite Data Unit frequency precompensation algorithm. — JW

Notice: The views expressed here are solely mine and do not representthe views of the Independent Group (IG), Jeff Wise, or any other group or individual. — VI


In previous work, paths were reconstructed for MH370 using the available radar and satellite data. Paths to the north of Malaysia were studied bymatching the measured Burst Timing Offset (BTO) data, but relaxing the constraint of matching theBurst Frequency Offset (BFO), which is appropriate if the BFOdata waseithercorrupted or misinterpreted. It was found that there are paths to the north that end at airports that could be reached with the fuel that was loaded onto MH370.In this work, the conventional interpretation of the BFO is challenged. In particular, the possibility that the operation of the SATCOM was deliberately modified so that a northern path would have the BFO signature of a southern path is studied. Some of the findings are:

  • The Honeywell Thales MCS-6000 SATCOM used by MH370 hasafrequencycorrection algorithm withthe capability to correct for the Doppler shift caused by inclination of thesatellite. This is known to the official investigation team butis not generally known by independent researchers.
  • The value of inclination for the Inmarsat I3F1 satellite that was broadcast by the Ground Earth Station (GES) at Perth, Australia, to be used by SATCOMs logged into the satellite, was zero. The true inclination of the satellite was around 1.65⁰. The two parameters that describe the satellite inclination, the inclination angle and the time of the ascending node, are stored in the System Table of the SATCOM in non-volatile memory, and are used by the frequency compensation algorithm.
  • If an individual obtained unauthorized access to the non-volatile memory of the SATCOM, the value of the inclination used by the frequency correction algorithm could be changed from 0 to 3.3⁰, or about twice the true inclination of the satellite. With this change, the BFO signature of a northern path that satisfied the BTO data would resemble the BFO signature of a southern path that satisfied the BTO data.
  • The apparent turn to the south between 18:28 and 18:40 UTC that is suggested by the measured BFO data might have been caused by a change to the inclination parameters stored in the SATCOM’s System Table during that time interval.
  • The calculated values of BFO for northern paths with the inclination parameter changed to 3.3⁰match the measured BFO values with an RMS error less than 3.8 Hz. This is true for Mach numbers between 0.65 and 0.85 at FL350, with little variationin errorseen in this speed range.
  • At each log-on, the inclination parameters would be reset to zero. Therefore, the BFO data associated with the log-ons at 18:25 and 00:19 UTC should be evaluated with inclination parameters set to zero. The BFO data at times between these log-ons should be evaluated with the possibility that a change was made.
  • The BFO value at 00:19 matches an aircraft along the northern part of the 7tharc on the ground and stationary once the BFO is adjusted for the log-on offset seen at 16:00 UTC. This suggests that if MH370flew north, it might havesuccessfully landed.
  • Researchers have identified security vulnerabilities in other SATCOMs, including backdoors and access to memory, although the MCS-6000 has not been specifically studied. The possibility of “spoofing” the BFO to disguise location has been considered before.

Read the whole report here.

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Guest Post: Stochastic Simulation of Hypothetical MH370 End-of-Flight Scenarios

Brock graph

Note: This paper was prepared by noteworthy independent MH370 investigator Brock McEwen, who set out to answer the timely question: has the soon-to-be-concluded search of 60,000 square kilometers of seabed in the southern Indian Ocean falsified the flight scenario proposed by the Australia Transport Safety Board and endorsed by unaffiliated researchers belonging to the Independent Group? Through extensive modeling, McEwen calculates that the search has covered more than 99 percent of the potential endpoints predicted by ATSB and IG flightpath scenarios. He concludes that “if both the Inmarsat signal data and its interpretation by search officials is valid, then the search should have turned up wreckage by now. This offers strong circumstantial evidence that either the Inmarsat data or its interpretation is invalid. Accordingly – unless search officials know something we don’t – the announced decision to spend another year searching around the improbable edges of a discredited theory (while this paper does not address surface debris, its absence likewise serves as strong Bayesian counter-evidence) is an extremely poor one.” — Jeff Wise

Executive Summary
This paper stochastically models MH370 end-of flight dynamics, and finds no evidence to support last month’s announced continuation of status quo search strategies. This finding is consistent with a documented pattern of decisions by MH370 search leaders which make no sense. A rigorous, independent audit of both the Inmarsat data’s entire chain of custody and MH370 search leadership is recommended.

In a joint statement issued April 16, 2015, Malaysian Transport Minister Liow Tiong Lai, Australian Deputy Prime Minister Warren Truss and Chinese Transport Minister Yang Chuantang indicated the search for Malaysian Airlines Flight 370 (MH370) would continue to focus on the deep-sea search in the Southern Indian Ocean (SIO):

“Should the aircraft not be found within the current search area, ministers agreed to extend the search by an additional 60,000 square kilometres to bring the search area to 120,000 square kilometres and thereby cover the entire highest probability area identified by expert analysis,” they said in a joint statement. “Ministers recognise the additional search area may take up to a year to complete given the adverse weather conditions in the upcoming winter months.”

In committing to this extension – described graphically as a modest search zone expansion in all four directions – search leaders implicitly assume that

  1. the Inmarsat data is sufficiently accurate and precise to permit interpretation by investigators AND
  2. the conclusion they drew (flight to fuel exhaustion, followed by pilotless spiral to impact) is correct, YET
  3. the wreckage this conclusion predicts remains outside the areas already searched by side-scan

This paper tests this hypothesis, via stochastic simulation of plausible post-fuel exhaustion flight paths.

You can read the full paper here.


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Guest Post: Northern Routes for MH370 Ending at Airports

by Victor Iannello

[Notice: The views expressed here are solely mine and do not represent the views of the Independent Group, Jeff Wise, or any other group or individual.]


Paths were reconstructed for MH370 using the available radar and satellite data. Paths to the north of Malaysia were studied by relaxing the constraint of matching the Burst Frequency Offset (BFO), which is appropriate if the BFO data was either corrupted or misinterpreted. The choice of paths was constrained by matching the Burst Timing Offset (BTO) data. Three airports were identified that are located near the 7th arc, as defined by the last BTO data point at 00:19 UTC: Kyzlorda, Almaty, and Kuqa Qiuci. The viability of each airport was determined based on fuel requirements. A fuel flow model was developed by reverse engineering performance data at Long Range Cruise (LRC) and Holding speeds, and then extrapolating the data to other speeds and temperatures.

The fuel flow model coupled with the path reconstruction model predicts that a flight ending at Kyzylorda is unlikely due to the high speeds and unfavorable headwinds. A flight ending at Almaty was deemed viable even when considering the uncertainty in the fuel consumption model. Alternatively, Boraldai Airport, which is close to Almaty Airport, is also viable. Finally, a flight ending at Kuqa Qiuci is considered possible, although the fuel margin is small. The paths to the airports are shown in Figure 1.

The possibility that the plane reached a runway at Yubileyniy was also considered. As Yubileyniy is 237 km (128 nm) beyond Kyzylorda, a landing there is predicted to be very unlikely.

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The Reasoning Behind the Continued Search of the Southern Indian Ocean for MH370

April search area small

The soon-to-be completed search area, in purple and orange.

Earlier this month, at a meeting between ministers from Australia, China, and Malaysia, the countries involved in the search for MH370 announced that, in the event that the plane was not found within the current search zone by the end of mission in May, the area would be increased “to extend the search by an additional 60,000 square kilometres to bring the search area to 120,000 square kilometres.” (The new area is outlined in red in the image shown here.)

I think it’s worth considering the logic behind this decision.

Last year the ATSB spent months carefully calculating the boundaries of the original 60,000 sq km area. What they wound up with was a rectangle about 1200 km long and ranging in width from 48 to 62 kilometers wide, straddling the 7th arc.

This area fit what the ATSB believed to be the most likely scenario for the final phase of the plane’s flight: that it flew straight on a southerly heading on autopilot and then shortly after 0:11 ran out of fuel — first one engine, then the second. After the second engine stopped, a backup system called the Auxiliary Power Unit (APU) would have kicked in, restoring a limited amount of electrical power. The plane’s satellite communications system would have rebooted, leading to the final “half ping” at 0:19.

As soon as the second engine failed, the engine would have entered a unpowered glide, much as the “Miracle on the Hudson” A320 did after its engines ingested a flock of geese. In this case, however, there would have been no pilot at the controls to guide the plane in for a smooth landing. What’s more, the power interruption would have turned off the autopilot. Uncontrolled, the plane would have gradually banked into a turn, which then would have grown steeper, devolving into a tight spiral dive that would have ended with the plane impacting the water at high velocity.

Let’s call this the “Unpiloted Fuel Exhaustion Scenario,” or UFES.

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Nautilus: Fear in the Cockpit

Nautilus TransAsia artThe morning of Feb. 4, 2015, was drearily normal in Taipei. With the sky blanketed in low clouds, pushed by a moderate breeze, the day was neither hot nor cold, neither stormy nor fair. For many of the passengers that filed aboard TransAsia Airways Flight 235 at Songshan Airport, the journey ahead promised to be similarly workaday: not a jaunt to some exotic clime, but an hour-long puddle-jump across the Taiwan Strait to the city of Kinmen, where many of the passengers had family and work obligations.

At the front of the plane, 42-year-old captain Liao Chien-tsung and 45-year-old first officer Liu Tzu-chung strapped themselves into their seats and ran through their pre-flight checklists. Shortly after 10.30 a.m. the last of the passengers settled into their seats and the cabin crew closed the doors. As the plane started to move, passenger Lin Ming-wei had a hunch that one of the engines sounded funny, and requested that he, his wife, and their 2-year-old son be seated on the right side of the aircraft.

With practiced efficiency, Liao guided the ATR 72-600 along the network of taxiways to Runway 10. After receiving permission to take off, he rolled forward and swung the plane over the centerline. Engine throttles full forward, the twin turboprop engines roared and shook as each machine’s quadruple blades chopped the air. Liao released the brakes, and the plane leapt forward. The airspeed indicator slid past 116 knots as the plane’s nose, then main wheels, lifted from the runway.

This moment—when a plane transitions from ground vehicle to air vehicle—is the most critical in aviation. It is the part of each flight when a plane has the least altitude, is moving the slowest, and carries the heaviest mass of fuel. Given how much happens in a short span of time, it’s also the most mentally demanding. As Liao felt the seat press into his back, his eyes flitted from the instrument panel to the runway and back. Simultaneously he had to keep the plane centered on the runway, monitor its speed and acceleration, pay attention to the radio, and keep alert for signs of malfunction.

Normally this critical phase is over within a few minutes. But every once in a while something goes wrong. For TransAsia 235, that day was today.

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Washington Post: Don’t Be So Quick to Believe that Andreas Lubitz Committed Suicide

What, exactly, are we talking about, when we talk about a man who deliberately flies a plane carrying 149 other human beings into the side of a mountain?

In a sense, we’re talking about a suicide. That’s a common enough thing. Plenty of people carry it out — 40,000 each year in the United States alone. You could also say we’re talking about murder, and that’s true, too. The other 149 people on board Germanwings 9525 had their lives taken from them, just as the 16,000 Americans murdered each year have.

Or you could invoke the specter of murder-suicide, that increasingly familiar explosion of self-consuming, purposeless annihilation — the disgruntled postal employee, the trench-coat-wearing high schooler, the well-armed moviegoer.

These violent acts strike seemingly indiscriminately. But they occur often enough that we can find a sense of understanding. We can draw up psychological profiles of attackers and study patterns of behavior to understand causes.

We know much less about pilots who fly their planes into the ground, because it’s so unusual.

Though pilots are under increasing stress, their mental health is carefully vetted. To become a commercial pilot, one must undergo physical and psychological screening. Additionally, pilots are a self-selecting group. They’ve earned their way to the cockpit through hard work, discipline and a willingness to take on as their regular daily routine an activity that many people consider too dangerous to do at all. In my experience interacting with pilots — I’m a recreational flier and an aviation journalist, so I run into quite a few — they tend to exhibit what psychologists call an “internal locus of control,” meaning that they believe that whatever obstacles lie before them can be tackled using their own resources.

How, then, could such a pilot kill himself along with all his passengers?

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Germanwings Flight 9525 — UPDATED


Germanwings 9525 co-pilot Andreas Lubitz (credit: Paris Match)

Yesterday morning, an old friend sent me a text: “Did you hear the news?”

I always get a pit in my stomach when I hear that. “No,” I emailed back. “What happened?”

What happened, of course, was Germanwings 9525. At the time all that was known was that an Airbus 321 carrying 150 people had crashed into the Alps. Soon enough details began to emerge, but how strange they were: a 24-year-old aircraft, en route from Barcelona to Dusseldorf, had climbed to its crusing altitude of 38,000 feet and then, within a matter of minutes, begun to descend at 3000 to 4000 feet per minute, apparently fairly steadily and while remaining on course, until it crashed eight minutes later into the French Alps. The flight crew issued no distress call.

I’d never heard of anything like it, but as the conversation developed online, some parallels emerged. Foremost was the case of LH1829, which took off from Bilbao last November and began an uncommanded descent of some 4000 feet per minute after the flight management system became confused by frozen angle-of-attack sensors.

In that case the pilots communicated with technicians on the ground and figured out how to solve the problem before a great deal of altitude was lost, but perhaps yesterday’s pilots had tried to tackle the issue by themselves and gotten too absorbed by the challenge to realize how much altitude they were losing, a la Eastern Air Line Flight 401?

Some speculated that a sudden decompression might have caused the tragedy. There have certainly been incidents in which aging, inadequately repaired aircraft have suffered catastrophic failure of their pressure hulls, leading to destruction of the plane, but those don’t generally look like this–the plane either breaks up at altitude or the pilots are able to don oxygen masks and keep flying the plane and communicating, if only for a while.

Another possibility–one hesitates to raise it in today’s climate of fear–is that a hijacker attempted to take control of the cockpit. I don’t think we can rule this out, either.

At this point, frankly, none of these scenarios make a great deal of sense, and I think the overall sentiment among people who spend a lot of time looking at this sort of thing is bafflement. “I’m at a loss,” one veteran 777 pilot emailed me yesterday. I think that about sums it up. Hopefully, the recovered cockpit voice recorder will provide some clarity.

UPDATE 3/26/2015: At a press conference in Marseille today prosecutor Brice Robin revealed that, according to audio recordings recovered from the Cockpit Voice Recorder, co-pilot Andreas Lubitz locked the captain out of the cockpit and initiated the descent that led to the plane’s crash into the Alps. “He took this action, for reasons we still don’t know why,” Robin said. “We can only deduce he destroyed the plane. He voluntarily allowed the plane to lose altitude. I think the victims only realised at the last moment because on the recording you only hear the screams on the last moments.”

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