The stuff we learn after a plane goes missing
(A version of this post, as written by me, first appeared in The Hindu science blog, The Copernican, on March 16, 2014.)
It’s likely any of you knew many of or all the following, but these are things I became aware of from reading news items and analyses of the missing Malaysian Airlines flight 370, currently one of hijacked, crashed into a large water-body or next-plausible-occurrence. While some of them may not directly apply to the search for any survivors or the carrier, all of them shine important and interesting light on how things work.
Ringing phones aren’t actually ringing. Yet. – After the relative of a passenger on board flight 370 called up the person’s phone, it started to ring. This was flashed on TV channels as proof of the plane still being intact, whether or not it was in the air. A couple hours later, some telecom experts wrote in that the first few rings you hear aren’t rings that the call’s receiver is hearing, too. Instead, those are the rings the network relays to you so you don’t cut the call while it looks for the receiver’s device.
Air-traffic controllers don’t always know where the plane is* – Because planes are flying at 35,000 feet, controllers don’t anticipate much to happen to them, and they’re almost always right. This is why, while cruising at that altitude, pilots don’t constantly buzz home to controllers about where their flight is, its altitude, its speed, etc. To be on the safe side, they buzz home over specific intervals, a process that’s automated on some modern models. Between these intervals, of course, the flight might just as well be blinking in and out of extra dimensions but no one is going to have an eye on it.
Radar that controllers have access to don’t work so well beyond a range of 150-350 km** – If civilian aircraft are farther than this, they no longer show up as pings on the scanning screen. In fact, in another system, called automatic dependent surveillance-broadcast (ADS-B), a plane determines its location based on GPS and transmits it down to a controller. Here again, there’s a distance limit of up to 300 or so km. Beyond this, they communicate over high-frequency radio. Of course, this depends on the quality of equipment, but it’s useful to know such limitations exist.
If a plane’s communication systems have been disabled, there’s no Plan B – There’s radar, then radio, then GPS, then a fourth system where the aircraft’s computers communicate via satellite with the airline’s offices. The effectiveness of radar and radio is contingent on weather conditions. Beyond a particular altitude and, again, depending on the weather, GPS is capable of blinking out. The fourth system can be be manually disabled. If a renegade technician on the flight knows these things and how to work them, he/she can take the flight off the grid.
For pilots, it’s aviate, navigate, and then communicate – If the flight is in some kind of danger, the pilot’s primary responsibility is to do those things necessary to tackle the threat, and try and get the carrier away from the danger area. Only then is he/she obligated to get in touch with the controllers.
The ocean is a LARGE place – Sure, we studied in school that the oceans cover 71% of Earth’s surface and contain 1.3 billion cubic km of water, but those were just numbers – big numbers, but numbers nonetheless. I think our sense of bigness isn’t reliant any bit on numbers but only on physical experiences. I’m 6’4″ tall, but you’ll have to come stand next to me to understand how tall I really am. That said, I now quote former US Navy sailor Jim Wright (from his Facebook post):
… even when you know exactly, and I mean EXACTLY, where to look, it’s still extremely difficult to find scattered bits of airplane or, to be blunt, scattered bits of people in the water. As a navy sailor, I’ve spent days searching for lost aircraft and airmen, and even if you think you know where the bird went down, the winds and the currents can spread the debris across hundreds or even thousands of miles of ocean in fairly short order. No machine, no computer, can search this volume, you have to put human eyeballs on every inch of the search area. You have to inspect every item you come across – and the oceans of the world are FULL of flotsam, jetsam, debris, junk, trash, crap, bits, and pieces. Often neither the sea nor the weather cooperates, it is INCREDIBLY difficult to spot [an] item the size of a human being in the water, among the swells and the spray, even if you know exactly where to look – and the sea conditions in this part of the world are some of the worst, especially this time of year.
Mr. Wright goes on to write that should flight 370 have crashed into the Bay of Bengal, the South China Sea or wherever, its leaked fuel wouldn’t exactly be visible as an oil slick because of two reasons: first, high-grade aircraft fuel evaporates really fast (if it hasn’t already been vaporized on its way down from the sky); second, given the size of the fuel-tank, such a slick might cover a few square kilometers: on an ocean, that’s a blip. The current extended search area spans 30,000 sq. km.
Military threats in militarized zones are discerned by ballistic trajectories of bodies – One of the simplest ways armored units know what they’re seeing in the sky is not a missile but a civilian aircraft is by their trajectory – the shape of their path. Most missiles are ballistic, which means their trajectories are like upturned Us. Aircraft, on the other hand, fly in a straight line. I suppose this really is common sense but it is good to know just what’s keeping me from getting bombed out of the air should I fly over, say, the East China Sea…
The global positioning system doesn’t continuously relay the aircraft’s location to controllers – See * and **.
Smaller nations advance pilots with fewer flying hours than is the norm in bigger nations – According to a piece on CNN, one of flight 370’s two pilots had clocked only 2,763 flying hours as a pilot, and was “transitioning from flight simulator training to the Boeing 777-200ER”. The other pilot had a little over 18,000 hours under his belt. As CNN goes on to explain, smaller nations tend to advance pilots they think are very talented, farther than they could go in the same time in other countries, through intensive training programs. I couldn’t find anything substantive on the nature of these supposedly advanced programs, so I can’t comment further.
Pilot suicide – Okay, what the hell. Nobody wants a person at the controls who’s expressed suicidal tendencies, and it’s the airline’s responsibility to treat or accordingly deal with such people. However, the moment you’ve said that, you realize how difficult such situations could be to predict, not to mention how much more difficult to prevent. A report by the US Federal Aviation Administration titled ‘Aircraft-Assisted Pilot Suicides in the United States‘, from February 2014, describes eight case-studies of flights whose pilots have killed themselves by crashing the aircraft. Each study describes the pilot’s behavior during the flight’s duration and is careful to note no other electric/mechanical failures were present. In the case of flight 370, of course, pilot suicide is just a theory.
The Boeing 777 is one safe carrier – Since its first flight in 1994, the Boeing 777-200ER (for ‘Extended Range’) had an estimated full loss equivalent (FLE) of 0.01 as of December 31, 2012, over 6.9 million flights. According to AirSafe.com, the FLE…
… is the sum of the proportions of passengers killed for each fatal event. For example, 50 out of 100 passengers killed on a flight is an FLE of 0.50, 1 of 100 would be a FLE of 0.01. The fatal event rate for a set of fatal events is found by dividing the total FLE by the number of flights in millions.
The same site also lists the 777-200ER as having the second lowest crash rate – 0.001 per million flights – of all time, among all models with 2 million flights or more, as of September, 2013. Only the Airbus A340 is better with a crash rate of 0, although it has clocked 4 million fewer flights (just saying).
Southeast Asia is a busy area for aviation – Between April-2012 and October-2013, the number of seats per week per Southeast Asian country grew by an average of 19.4%. In the same 18 months, the entire region’s population grew by 6% (both numbers courtesy the Center for Asia-Pacific Aviation). Then, of course, there’s Singapore’s Changi Airport. It’s one of Asia’s busiest, if not the world’s, handling 6,100 flights a week. And it was in this jam-packed area that people were trying to look for one flight.
For more on how we can manage to lose a plane in 2014, check out my previous post Airplanes Can Still Go Missing.
