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Why AirAsia 8501 Disappeared From Radar


Figure 1: ATC screen grab of QZ8501

One of the many baffling aspects of the QZ8501 story so far is why the plane disappeared from radar screens when it did. Did the plane suffer some kind of catastrophic event that caused the plane’s transponder to cease functioning? Or did something else occur?

I believe that we now have enough information to answer that question.

All we know about the plane’s final moments comes via two images that were apparently leaked from the official inquiry. The first (figure 1, above) is said to be a screen grab from an air traffic control (ATC) screen shortly before the plane disappeared. The second (figure 2, after the jump) is a screen grab taken very shortly afterward, this time from what looks to be some kind of analysis software, showing the plane’s speed, heading, rate of climb, and so forth.

According to Embry-Riddle Aeronautical University professor Martin Lauth, who helped me to understand the symbology of figure 1, the yellow arrow is pointing at the symbol for the plane in question, here designated “AWQ8501.” The number to the right, 353, is the ground speed of the plane in knots. The number below, 363, indicates that the plane was at 36,300 feet, and the white arrow to the right of it shows that the plane was climbing.

Next, let’s talk about the four white lines coming from the QZ8501 symbol, starting with the one heading more or less straight down and connecting it to “AWQ8501.” That line just indicates which symbol the tag corresponds to. Moving clockwise, we next find a much shorter line sticking to the left. This is a visual indicator of how far the plane will move in a certain amount of time — controllers typically set it for anywhere from one to three minutes, and in this case it seems to set for one minute. We already know the speed of the plane, but this line tells us its heading: a little south of due west, on a heading of 265 degrees true.

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Airliners in Unusual Attitudes

One of the things that’s being talked about a lot in the coverage of AirAsia 8501 is the idea that under certain circumstances a commercial airliner might start to go too slow, stall, and fall out of the sky. But does that happen? I scoured by brain, did some Google searches, and asked Twitter, but I haven’t found a single case of a classic power-off stall by a commercial jet at altitude. Then again I did find some accident and incident reports that seemed germane to the case. I’m listing them below; if anyone wants to alert me to others I’d be grateful.

 ANA (flight number unknown), September 6, 2011. “Two flight attendants were slightly hurt and four passengers got airsick when the All Nippon Airways Boeing 737-700 with 117 people aboard descended sharply, veered off course and went belly up over the Pacific on its way from southern Japan to Tokyo on Sept 6. ANA said Thursday that the co-pilot is believed to have mistakenly hit the rudder controls instead of the door lock to allow the pilot back in the cockpit. It said the crew managed to stabilize the plane after the co-pilot’s error and land it safely.”

Air France 447, June 1, 2009. The only true case I’ve been able to find of a commercial jet experiencing a stall at altitude and fatally crashing. The kicker is that the plane was held in the stall by a disoriented pilot.

Qantas flight 72, October 7, 2008.  “While the aircraft [Airbus A330-303] was in cruise at 37,000 ft, one of the aircraft’s three air data inertial reference units (ADIRUs) started outputting intermittent, incorrect values (spikes) on all flight parameters to other aircraft systems. Two minutes later, in response to spikes in angle of attack (AOA) data, the aircraft’s flight control primary computers (FCPCs) commanded the aircraft to pitch down. At least 110 of the 303 passengers and nine of the 12 crew members were injured; 12 of the occupants were seriously injured and another 39 received hospital medical treatment.

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Why Thunderstorms Are So Dangerous for Airliners

airplanethunderstormAs I write this, AirAsia flight 8501 has been missing for less than 24 hours, and in the absence of wreckage its too early to speculate on what happened. But the flight, which took off from Surabaya bound for Singapore, appears to have been traveling through an area of intense thunderstorm activity, so it may be instructive to look at the kind of danger this sort of weather can present to aircraft.

The region around the equator is known to meteorologists as the Intertropical Convergence Zone, or ITC. Here, the heat and moisture of warm ocean waters provides the energy to power tremendous updrafts that produce clusters of thunderstorms called a Mesoscale Convenction Complex. These storms can punch up through the stratosphere up to 50,000 feet, far above the crusing altitude of commercial airliners. From

A thunderstorm brings together in one place just about every known weather hazard to aviation. A single thunderstorm cell can hold 500 000 tons of water in the form of liquid droplets and ice
crystals. The total amount of heat energy released when that much water is condensed amounts to approximately 3 x 1014 calories. Equated with known energy sources, this falls just below an entrylevel hydrogen bomb. Even a small thunderstorm would have the caloric equivalent of a Hiroshimatypeatomic weapon… The thunderstorm occupies a unique place in the pantheon of aviation meteorology because it is the one weather event that should always be avoided. Why always? Because thunderstorms are killers.

Some of the deadly forces include lighning, airframe icing, large hailstones, extreme turbulence, and downdrafts that can reach speeds in excess of 100 mph. Perhaps the greatest hazard facing a modern airliner, however, is the sheer volume of precipitation that a thunderstorm can put out.

On May 24, 1988, a TACA 737 en route from Belize to New Orleans was descending towards its destination when it blundered through a thunderstorm. At an altitude of just 2000 feet, a deluge of rain and hail doused the flames of its twin turbofans. Unable to regain power, the captain managed through superb airmanship to put the stricken plane down undamaged atop a mile-long levee. Notes superb aviation writer Peter Garrison:

The event was not unique. Nine months earlier, an Air Europe 737 descending through rain and hail over Thessaloniki, Greece, had suffered a double flameout. In that case, the crew managed to restart the engines and land without trouble. In 2002, a Garuda Indonesia 737, also descending among thunderstorms, suffered a double flameout over Java. Its crew ditched the airplane in a river; one person died, and there were a dozen serious injuries.

According to preliminary reports, the pilot of QZ8501 had asked air traffic control for permission to ascend from 32,000 to 38,000 feet in order to evade the weather. Historically, however, attempting to fly over a thunderstorm has proven a dangerous strategy. In 2009, Air France 447 was flying through the upper reaches of a thunderstorm when it hit turbulence and its pitot tubes froze, leading to loss of airspeed indication; in the ensuing confusion the pilot flying lost situational awareness and flew the plane into the ocean.

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Sense and Nonsense in MH370 Coverage


Search area imaged by Go Phoenix. Courtesy ATSB.

In some ways, the search for MH370 is going exceedingly well this week. The agency leading the search in the Indian Ocean, the Australia Transport Safety Board (ATSB), just released more information concerning technical aspects of the signal data, which will allow the Independent Group and other amateur investigators to refine their analyses of the plane’s final trajectory. The ships scouring the seabed looking for wreckage continue to press forward with their monumental task, and have now completed more than 12,000 square kilometres of the planned search area. And the respected British aviation website,, has published a brand-new analysis by independent investigator Simon Hardy which reinforces the work of the ATSB and the IG.

And yet, this isn’t the news that’s making headlines. What is? Try Googling the word “airliner.” The top return will link you to a theory by author Marc Dugain that was published by Paris Match. Dugain believes that MH370 was taken over by hackers and shot down by the US to prevent the plane from being used in a 9/11-style attack on the base at Diego Garcia. I could try to dismantle this notion methodically but suffice to say that it is as baseless as it is incendiary. Meanwhile, as if resonating to the same frequency of bonkersness, the UK Independent published a story today entitled “Malaysia Airlines flight MH370 theories: 17 possible explanations that could reveal fate of plane,” a compendium of conspiracy theories all of which were disproven long ago.

Why are experiencing this onslaught of MH370 nonsense right now? I think the problem is really two-fold.

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Russian Military Planes, Flying With Transponders Off, Provoke Alarm in Europe

FIR maps small

credits: left, Financial Times; right, SkyVector


In the latest in series of aggressive maneuvers by Russian military planes in European airspace, the Financial Times is reporting today that a Russian intelligence plane nearly caused a mid-air collision with a Swedish passenger jet on Friday while flying along a Flight Information Region (FIR) boundary with its transponder turned off.

An SAS jet taking off from Copenhagen on Friday was warned by Swedish air traffic control to change course to avoid a Russian military intelligence flight, said Swedish authorities.

Peter Hultqvist, Sweden’s defence minister, said it was “serious, inappropriate and downright dangerous” that the Russian aircraft was flying with its transponder — used to identify its position — switched off. He told Swedish reporters: “It is remarkable and very serious. There is a risk of accidents that could ultimately lead to deaths.”

The incident is the latest in a series involving Russian military aircraft over the Baltic Sea this year. In March, an SAS airliner came within 100 metres of a Russian military aircraft shortly after take-off from Copenhagen, Swedish television reported.

In the most recent incident, the Swedish and Danish military detected the Russian aircraft in international airspace on radar and warned the SAS flight, said to have been bound for Poznan, Poland.

A story about the incident in WAtoday links to a YouTube clip of ATC audio combined with speeded-up playback the commercial flight from, which indicates that the incident took place near the boundary between two FIR zones, Sweden and Rhein-UIR, with the Russian plane flying west to east along the boundary.

As I wrote in an earlier post, military pilots have been known to fly along FIR boundaries with their transponders turned off as a means of escaping detection. In what may or may not have been a coincidence, after it deviated from its planned course to Beijing, MH370 flew along the FIR boundary between Malaysia and Thailand with its transponder turned off. The pilot in Friday’s incident may have been testing NATO air defense systems to see how well the technique might work over busy Europeans airspace.

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Up Close: Inside an IG Southern Route

Richard v13.1 Route

Ever since the Independent Group first issued a public report offering guidance as to where search efforts for MH370 should be concentrated, people have been asking for details on group members’ calculated routes. Unfortunately, everyone is doing this work for free, in their spare time, and have other things to attend to as well, so providing explanations has not been a priority. At last, however, Richard Godfrey, one of the hardest-working of all, has gallantly stepped up and delivered a polished-up version of his latest theory so that all interested parties can have a look under the hood. Above is a screen shot of his model, which he dubs “MH370 Flight Path Model V13/1 Final,” as it appears in Google Earth. Details after the jump.

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MH370 Final Major Turn Timing

Path derived from V13.1 Path Model

Path derived from V13.1 Path Model

Guest Post by Michael Exner, Richard Godfrey, and Sid Bennett (Members of the Independent Group)

Beginning shortly after the release of the redacted Inmarsat data log on May 26th, 2014, independent investigators began analyzing the data using analytic models, with the goal of estimating the most likely end point for the flight path of MH370. A combination of secondary and primary radar data provided information about the path from takeoff at 1641UTCto 1822UTC. In its June 26th, 2014 Report, ATSB assumed that MH370 was headed southby 1941UTC, but left open the question of where MH370 went between 1822UTC and 1941UTC. In its second report on July 17th, 2014, the Independent Group (IG) pointed out that the ATSB analysisappeared not to considerthe available Inmarsat data at 1840UTC, and recommendedthat ATSB consider that the Final Major Turn (FMT) to the south may have occurred much earlier than 1941UTC. In its September 9th, 2014, Search Area Recommendation, the IG noted that recent news reports indicatedthat ATSB was reconsidering the time of the FMT, based on the “phone call data” at 1840UTC. On September 26th, 2014, the IG released a Further Progress report in which the IG concluded MH370 must have been flying in a southerly direction by 1840UTC. On October 8th, 2014, ATSB released an Update wherein they also concluded that the FMT must have occurred before 1840UTC, similar to the published IG analysis. Thus, ATSB and the IG agreed by October 8ththat the FMT must have startedbetween 1822UTC and 1840UTC.However, a more exact time for the FMT has remained uncertain. A closer look at the BFO data after 1825 suggests that the FMT started and ended close to 1840UTC.

Read the full report here.


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Occam’s Razor is Overrated

conspiracy theoryMartin Dolan, chief commissioner of the Australian Transport Safety Bureau (ATSB), is plagued by conspiracy theorists. According to an article in the Sydney Morning Herald, since the disappearance of MH370, “conspiracy theorists have been busy trying to solve the mystery themselves. Many have contacted Dolan.”

“You’ve got this big mystery and everyone wants to know the answer and everyone wants to help,” the SMH quotes Dolan as saying. “It’s unhelpful, for the sake of the families more than anything else, in the sense that it has the potential to undermine confidence in what we are doing.”

I feel somewhat guilty for being one of those peanut-gallery denizens who have tormented him. Along with my fellow obsessives in the Independent Group, I’ve been straining my brain for the last eight months trying to make sense of the strangest aviation mystery in history. Yes, I’d like to be helpful; yes, I’d like to know the answers. And yes, I may have unwittingly undermined confidence in what the ATSB was doing, for instance by publicly saying that I thought they were looking in the wrong place. (Though, to be fair, they were in fact looking in the wrong place.)

Nevertheless, I must take issue with one aspect of the article’s characterization of my subculture: the use of the term “conspiracy theorist.” Now, look: I get it. My wife says that I remind her of the Kevin Costner character in “JFK.” I ruminate about the intracacies of a famous case and try to piece them together in a new way that makes more sense. I’m obsessed.

There’s a big difference, however, between true grassy-knoll conspiracy theorists (or 9/11Truthers, or the-moon-landing-was-faked believers) and MH370 obsessives like me. It’s this: there is no default, mainstream narrative about the missing Malaysian airliner. There is no story that officials and all reasonable people agree makes sense.

This isn’t the result of laziness or incompetence. It’s just that the data is so strange.

A lot of people don’t get that. Ever since the mystery began, certain voices have been invoking the principle of Occam’s razor, saying that when we try to formulate a most likely scenario for what happened to the plane, we should choose the answer that is simplest. People who are making this argument are usually in favor of the argument that the plane suffered a massive mechanical failure and then flew off into the ocean as a ghost ship, or that the pilot locked his co-pilot out of the cockpit and committed suicide. However, as I’ve argued over the course of several earlier posts, neither theory matches what we know about the flight.

Instead, I’ve argued that an accumulation of evidence suggests that MH370 was commandeered by hijackers who had a very sophisticated understanding of airline procedure, air traffic control, avionics systems, military radar surveillance, and satellite communications. In other words, what happened on the night of March 7/8 of this year was a intentional act. And when it comes to human schemes, Occam’s razor goes out the window. Instead of simplicity, we should expect complexity, not to mention red herrings and any other form of subterfuge.

Whenever I hear Occam’s razor invoked, I inevitably find myself thinking of something that Sarah Bajc said on CNN. Bajc’s partner, Philip Wood, is one of the missing passengers, and she has been very open minded in considering alternative explanations to what happened that night. “There are 40 crazy stories that you could tell about MH370,” she told the anchor. “And one of them is going to turn out to be true.”

I’ve come to think of this as the Bajc Postulate, which I think should replace Occam’s Razor in situations like this. It goes like this: “When trying to unravel human deception, don’t expect simplicity.”

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Why MH370 Search Officials Can’t Agree Where to Look

source: ATSB, modified by JW

In dispute: whether the search should focus on the area spotlighted by data error optimisation or constrained autopilot dynamics


Disquieting news in the Wall Street Journal today; the paper reports today that the official inquiry into the disappearance of missing Malaysia Airlines flight 370 is riven with disagreement:

Ongoing differences of opinion between five teams of experts that include Boeing Co. and the Australian military have led to search vessels being deployed in two different priority search areas. These zones overlap in some places but in others are hundreds of miles apart, highlighting how efforts to solve one of modern aviation’s biggest mysteries remain little more than educated guesswork. Searchers may only be able to scour around 80% of the probable crash sites before government funding runs out.

For its part, the Australian Transport Safety Board (ATSB) issued a response that essentially confirmed the gist of the WSJ article:

[ATSB chief commissioner, Martin] Dolan said that earlier there had been consensus amongst the five groups, based on the data available at the time, but once the data had been refined, “the results from the methodologies did not coincide exactly. There is no disagreement, just the deliberate application of differing analysis models,” said Mr Dolan.

One would like to think that, nine months after the plane went missing, that the experts would have ironed out any loose threads in their understanding of the plane’s final trajectory. Especially given the fact that Inmarsat scientist Chris Ashton told the BBC program Horizon that the company had cracked the nut way back in March, saying: “The graphs matched, the data worked, the calculation was solved.”

But if we take a closer look at the history of the accident investigation, it’s not surprising disagreements exist. For all the confident press statements that the authorities have released, behind the scenes investigators have always struggled to make sense of the data in their possession. It’s not a matter, fundametally, of a difference in opinion between experts; it’s a matter of inconsistencies within the data sets themselves.

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How We Can Tell How Fast MH370 Was Flying

Early Inmarsat route calculation, from Ashton et al.

Early Inmarsat route calculation, from Ashton et al.

A week after MH370 went missing, the Malaysian government dropped a shocker: Inmarsat, the satellite communications provider, had recorded signals from the plane that allowed them to calculate the plane’s distance from the satellite about once an hour for nearly six hours.

At first, the Malaysians only released a rough sketch of the final arc: two matching fragments of a circle, 3000 miles in radius, that stretched from Kazakhstan in the north to the remote Indian Ocean in the south. This in itself was a major step forward, in that it drastically reduced the numer of possible places the plane could have gone. But even more enticingly it suggested that if we had the numerical values for all the pings, and could figure out what speed the plane was flying at, we would be able to identify the route that the plane was taken and thus its precise final destination.

The scientists at Inmarsat recognized this immediately, and as Chris Ashton et al relate in their paper in the Journal of Navigation, they quickly plugged in the most logical speed value — typical airliner cruise speed, around Mach 0.83 — and concluded that the plane flew either to the middle of Kazakhstan or almost directly south into the Indian Ocean. (See image above.) As a result, the Malaysian government submitted a request to the Kazakh government asking that it be allowed to set up a search operation in the country, and planes were dispatched to search the ocean surface near the southern potential end point. Hopes were high. After satellites spotted what appeared to be floating material in the southern ocean, Australian Prime Minister Tony Abbott told his country’s parliament that it was a “potentially important development.’’

Of course the idea that the plane flew straight and fast, as airliners typically do, was just an assumption. Theoretically, it could have flown from ping ring to ping ring at any number of speeds along any number of routes, including straight, curvy, and zig-zag. Most of these alternatives would have resulted in the plane winding up at a lower latitude. And indeed, within a few days the authorities abandoned the southernmost search area and started scouring a section of the ocean much further north. The decision to shift the search zone appears to have been heavily influenced by a second set of data also derived from the handshakes exchanged between the plane and the satellite: the so-called BFO (“burst frequency offset”) data. After much head-scratching, Inmarsat believed that they had come up with an algorithm that allowed them to understand the physical implications of this data, and it told them that a) the plane had definitely gone south, not north, and b) the plane had not been flying straight and fast, as initially supposed, but instead taken a slower and/or meandering course and wound up about a thousand miles from the initial search area.

Frustratingly, for those of us who were watching from the sidelines and eager to understand what was going on, neither Inmarsat nor the Malaysians were willing to either release their numerical data nor to explain their BFO algorithm. We just had to take their word for it. Which was enormously frustrating, since it seemed tantalizingly plausible that if we had the data and understood the physical processes that generated it, we would be able to mathematically solve for the location of the plane. Et voila: mystery solved.

Finally, after much pressure from the public, the Malaysians did finally release most of the Inmarsat data in May; the following month, the Australian Transport Safety Bureau (ATSB) released a report which explained how the then-current search area had been arrived at and explained in some detail how the BFO algorithm worked.

Many independent experts, including members of the Independent Group, leapt at the chance to finally get under the hood of the BFO algorithm and see if they could reach their own conclusions about where the plane went. In time, however, their optimism faded. In turns out that the BFO data offers only a very imprecise gauge of a plane’s location or direction of travel. To test the algorithm, for instance, scientists working for the search effort compared BFO data received from a known flight with the plane’s actual path. They found that, of the thousands of possible paths that matched the BFO data, even the one that most closely matched the actual flight was hundreds of miles off in places.

We seemed to be almost back to where we started: we had a set of ping rings that showed us seven quite accurate (within 10 km, the ATSB estimates) arcs along which the plane must have been at seven moments in time, but with only vague intimations of where along those arcs the plane actually was.

Gradually, however, without much fanfare, it has become clear that other, non-BFO techniques can provide insight into how MH370 was traveling after it disappeared from radar, and these in turn offer a strong suggestion about where the plane went.

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