25 thoughts on “The Malaysian Air Flight”

  1. The industry is already working on carrying ADS-B positional data via Iridium satellites. This allows for tracking well outside of radar range. Iridium-style constellations of high-inclination LEO satellites would be a natural for this job. They offer true global coverage without requiring high-gain directional antennas. NAV CANADA is very active in the project because it’ll allow much better air traffic control over oceans and sparsely populated land masses.

    1. ADS can already be sent over satellite as an ACARS payload. I presume Iridium is just low enough in orbit to receive normal ADS-B transmissions without requiring a satellite terminal in the aircraft.

      But that doesn’t help if the aircraft stops sending any, which appears to be the case here.

      1. Some people are proposing to send regular data packets containing positional data, velocity and some telemetry points at regular intervals via Iridium. This would create a real-time black box report that could narrow the search area and give preliminary evidence of the problem. ACARS apparently only reports when abnormal readings exist. They also need to have the system equipped with a backup battery to keep transmitting even in the event of a catestrophic failure like TWA 800.

        1. ACARS is just a communications protocol, kind of like IP on the Internet. Amongst other things, it’s used for maintenance data, weather reports, requests for sports scores, and air traffic control data like ADS. Typically, the ADS messages are only sent every few minutes that way, because satellite data is expensive, but they are sent on a regular basis when requested by the air traffic control centre.

          In this case, it seems the aircraft stopped sending any kind of ADS messages when the transponder went off.

  2. Flightradar24.com has ads-b coverage throughout that area. It just stopped, at cruising speed and altitude, just after a slight turn at an IFR waypoint.

  3. I wasn’t very impressed by Ms. Peterson’s article. Satellite coverage is not ubiquitous nor is it cheap. Further, the article asks a question it never answers. There have been many erroneous reports, but one that seems to be sticking is that the aircraft turned off its transponder and then changed directions. If this holds up, then the transponder was somehow disabled. ADS-B can also be disabled. It’s not a guarantee that the technology would make a difference. Ms. Peterson assertion that the technology is present is like claiming that washing machines exists and therefore every home in the world should have one.

    Hence, the first comment from one of her readers suggesting that the technology isn’t utilized because of greed.

  4. I wonder if anyone has thought to check the logs of cell phone towers in the region to see if any of the phones on board came within coverage of towers outside the expected areas.

  6. How could it vanish from “radar” and continue flying? Easy. That’s an ADS-B Mode C system. It’s not real radar; it can’t do a skin paint. It relies on the transponder on the aircraft unless paired with an active air-search radar.

    So, how could this happen? At least three ways; someone turned the transponder off, or the plane had an electrical failure, or, it dropped below coverage. Given the range and location, my wild guess is the coverage floor in that area is around 28,000 feet.

    That kind of transponder emits when interrogated, so if the plane drops below the coverage floor (which varies due to terrain and range) it effectively vanishes.

    It’s obvious at this juncture that the plane isn’t down where it “vanished”. So, what could have happened? My personal guess would be either hijacking, or hypoxia. If the plane was off autopilot when the crew lost consciousness, it could have flown on, erratic in both altitude and heading, for quite some time. What makes me think hypoxia due to a pressurization system issue is the timing; it had only been airborne 40 minutes, so would have only been near cruising altitude for less than that. And, even if the cabin O2 masks deployed, if the crew was unconscious and thus the plane stayed at high altitude, the cabin O2 masks would run out of O2 in short order (they only have a few minute’s capacity).

    This hypoxia scenario has occurred in the past, including in the USA. Here’s a link to a Wikipedia page about a US incident,. and at the bottom it has a link to the Greek airliner.

    I find some aspects of the search very questionable. For example, the initial myopic focus on one suspected area. Once they had it adequately searched, why not check outlying areas based on probability metrics with at least a small fraction of the air search assets?

    My own hunch would be to first identify areas where the plane could have come down and yet remain unlikely to have had its debris field encountered. That means low traffic areas or uninhabited rugged land. So, the Andaman sea or the mountains of the Isthmus of Koa.

    1. ADS-B uses transponder Mode S, not Mode C. Air traffic control radars can still get a rough paint on an aircraft without a transponder but it won’t have identifier or altitude information. Military radars don’t depend on transponders. There are reports that at least one military radar tracked the plane after it apparently turned around but some are disputing those reports. At the moment, it’s still a mystery.

      1. @ Larry J,

        You’re right, it’s mode-S. I relied on memory and should have checked that (my memory is unreliable, but only on days ending with a Y)

        ATC can only get a paint if they have a primary radar operating; if they don’t, or the plane isn’t in range of the primary, they can’t get a skin paint.

        My guess as to the confusion over the military data; it was a primary system, a skin paint, and they got a hit on something, but they aren’t sure what it was.

    2. The hypoxia theory is interesting, and what I say next isn’t meant to dismiss it. At altitude, at least on of the pilots should have been on a secondary oxygen mask, which is the primary mitigation for this type of scenario. Of course that requires a person to follow procedures. As for the passenger oxygen masks, I don’t think they would deploy without a rapid pressure change. But then, that would just mean they were never a factor.

      Right now, with the number of days gone by without much trace, I think any plausible scenario should be considered.

      I note that the Malaysian air force is starting to retract the notion that they tracked the aircraft after it possibly altered course. Either way, I would be surprised if a 777 landed in the Malacca Strait and no vessel saw it and reported it. I suppose they should search it, but it seemed like a waste of time. If it flew that way, I wouldn’t expect someone to dump it into the nearest body of water, after they just deviated from another large body of water.

      1. @ Leland,

        CFR 135 specified an either/or between 25000 and 35000 feet; either one pilot on a mask, or, have quick-don masks available. (and most go the latter route these days)

        Granted, that’s a US reg, but FAA regs are often used for guidelines worldwide.

        So, I think it’s at least possible that neither pilot was on O2.

        BTW, I’m not saying that I believe my hypoxia theory is correct, only that it is possible based on known facts. 🙂

    3. I’m skeptical of the hypoxia story. In order for that to work the aircraft needs to be at an altitude that would cause incapacitation, and wouldn’t that also leave it visible to radar? The airplane that Payne Stewart was on was tracked through it’s full flight. Granted that was mostly US airspace but it was also a much smaller plane.

      1. @ Curt Thompson,

        YEs, in order for the hypoxia theory to be plausible (assuming the facts regarding the last known transponder ping are accurate) the aircraft would have had to be at an altitude that would cause incapacitation, and then rapidly descend to below the coverage floor of the transponder-based radar. (with a caveat)

        The cruising altitude (variously reported between 32000 and 35000 feet) fulfills the incapacity requirement, especially as the plane had just finished climbing to that altitude. The altitude and timing fit for that part.

        Now we get to the problematic part; radar floor for that system. What was it? That depends on distance and terrain issues for the ground based sender. Seeing as how the vanishing occurred at or near the ATC zonal hand-off, I’m speculating that there were near max range, and so the floor would be high (especially at that distance). I doubt it’s less than 25,000 feet, and may be higher. Also, we’re talking line of sight systems here, and from 30,000 feet, the horizon is 212 miles away, so that’s the max theoretical range to that altitude under perfect conditions.

        So, a rapid descent (such as an impaired pilot, prior to loss of consciousness but realizing what’s happening, disengaging the autopilot and shoving the nose down) may well have put them below the coverage floor . A further possibility; the transponder antenna is, I think, on the plane’s belly, so a bank to either side would obscure it for a while. As for it being visible on primary radar; at that distance from the coast, it may well not have been, even assuming they had one operating.

        As to the caveat; there’s the possibility ( very small one, granted) that the impaired pilots, while trying to troubleshoot, inadvertently switched off the transponder.

        I’m not saying I believe in my hypoxia theory, just that I think it’s possible at this juncture. The only other scenario I see being possible at this point is a hijacking (and the hijackers shut off the transponder). I just don’t see other scenarios being viable because they all pretty much require the plane to have gone down at or near the primary search area, and so it’d have likely been found by now. So, that leaves a scenario where they ended up elsewhere, and that narrows the field by a bit.

        One other scenario that might fit; a major electrical problem that took out the transponder and other comms systems, plus some instrumentation. They may well have attempted to turn back, but them become spatially disorientated (it was night) and crashed.

  7. One crew member is supposed to be “on oxygen” . . . except if the plane is equiped with a “quick bail” mask.

    Back in the pre-911 days when you could look into the cockpit without causing a scare, I remember seeing at each pilot’s station this basket-like thing connected to a hose. It has a prong that goes over the back of the head to hold the mask snuggly in place, and I guess it can be donned in 1 or 2 seconds by simply grabbing it and sliding it over your head. I am thinking that only GA Weenies with planes such as the Piper Malibu capable of operating at the flight levels wear a mask.

    Look at the Wikipedia article http://en.wikipedia.org/wiki/1999_South_Dakota_Learjet_crash

  8. https://www.federalregister.gov/articles/2013/11/18/2013-27343/special-conditions-boeing-model-777-200–300-and–300er-series-airplanes-aircraft-electronic-system

    “The proposed architecture is novel or unusual for commercial transport airplanes by enabling connection to previously isolated data networks connected to systems that perform functions required for the safe operation of the airplane. This proposed data network and design integration may result in security vulnerabilities from intentional or unintentional corruption of data and systems critical to the safety and maintenance of the airplane. The existing regulations and guidance material did not anticipate this type of system architecture or electronic access to aircraft systems. Furthermore, regulations and current system safety assessment policy and techniques do not address potential security vulnerabilities, which could be caused by unauthorized access to aircraft data buses and servers.”

  9. So the thing from a year ago is that breathing airplane cabin air can be bad for you.

    http://thearrowsoftruth.com/tag/787-dreamliner/

    Cabin pressurization is typically from compressor bleed air. The claim is that this air can be contaminated by oil fumes (or worse) from the jet engine compressor stage.

    Who knew? This may be one of these ambulance-chaser alarmist-enviro things, but in steam locomotives, they had to have an oil-water separator if they wanted to use a portion of the exhaust steam for various purposes, including condensing part of it in a feedwater heater or exhaust-steam injector to return as boiler feed water.

    Because of the cylinder lube, folks don’t think of drinking condensed steam locomotive exhaust, but I guess we have been breathing air downstream of a jet engine compressor when we fly jets without thinking about it.

  10. The other thing about hypoxia is that a small leak can cause gradual onset of symptoms of “cognitive impairment”, that is, getting “stupid.”

    There is a cabin pressure alarm for pressure altitude below 10,000 ft MSL, but no one figured out what really happened to golfer Payne Stuart’s pilots.

    1. A 777 has an interior volume perhaps 100 times or more than that of a Learjet. A sudden depressurization at that altitude is a lot harder in a plane with the volume of a 777 – a hole big enough to cause the plane to rapidly depressurize would likely be big enough to bring down the plane. It’s a lot easier to lose cabin pressure very quickly in a Lear (IIRC, a model 35). The period of useful consciousness at 35,000 feet is perhaps 30 seconds. If they lost cabin pressure and for some reason the backup oxygen masks failed (empty O2 tanks, mechanical malfunction, poor maintenance, etc.) then they’d be screwed. For anyone interested, here’s more info than you ever likely wanted to know about the 777 cockpit emergency oxygen system. It’s a 14+ MB PDF file of a 2011Egypt Air 777 cockpit fire (fortunately on the ground) probably caused by an electrical short circuit in the copilot’s oxygen hose.

    2. My understanding of the Payne Stewart incident was that the pressurization system had recently been maintained, a step to assure pressurization was occurring was skipped by routine, and the aircraft was never pressurized.

  11. A rough pilot is getting near the top of the list for me,

    Another point is that the number of times “maintenance” before the flight contributes to the downing of aircraft is surprising.

  12. The range for the transponder should be *longer* than that of the primary radar. The transponder is dealing with an R^2 (distance squared) signal loss, while the radar is dealing with R^4. The transponder is also operating at a slightly lower frequency which again gives it an advantage over the radar primary return.

Comments are closed.