Saturday, March 15, 2014

LOST

II might as well post this now, because I won't have a chance to update it if the mystery of Malaysian Airlines 370 is solved in the next few days. I don't have any special insights about the disappearance of an entire Boeing 777, but as a pilot I have to wonder about it.

First off, despite what movies like Airport '77 depict, an airplane that crashes into the sea doesn't slip whole and undetected under the waves. With considerable skill, or even questionable skill and some luck, it could alight on the surface of the water without substantial damage. Handled as if it were being landed on land, an airplane can skim over the surface of the water the way a skipped pebble or a snowmobile does. (Unlike the snowmobile, an airplane doesn't immediately sink, because the fuselage is full of air, and buoyant). No sane person would deliberately ditch an aircraft without a substantial emergency, because if something goes slightly wrong, the picture is substantially different. The video below is of a hijacked Ethiopian Airlines aircraft that was out of fuel. The captain was trying to ditch it while fighting with the hijackers. Even that fuselage stayed afloat for a reasonable amount of time, and many of the deaths were not due to crash injuries, but because passengers inflated their life vests before exiting the aircraft, impeding evacuation.

There's a post being shared on Facebook that purports to show the aircraft recovered, but you can tell from the still that it's actually a Lion Air landing accident from last year. Don't click that one because it's probably a virus.

When an airplane comes into contact with it, water is really quite a bit like ground. Do it in landing configuration, descending towards the water at a shallow, about three degree angle, then touching down wings level, slightly nose up and it is quite survivable. Do it at high speed, or inverted, or any other way that doesn't involve control at a low descent rate, and the result is catastrophic. Swiss Air 111 hit the water 20 degree nosedive, and at a bank turn angle of 110 degrees, and disintegrated into millions of pieces. Only one of the passengers was visually identifiable. Alaska Airlines 261 was a similar story. Many of the millions of pieces that make up an airliner and its contents float, so the debris is visible on the surface and drifts ashore. Jet fuel is oily, and floats on water leaving a visible slick. Also both those crews were in contact with air traffic control during the sequence that led to the crash.

When an aircraft suddenly disappears from radar and stops transmitting, one good guess is that it broke up in midair. But when that happens the pieces are in the water in roughly the area where the radar track stopped, and the last week has seen ships, helicopters satellites and and airplanes tasked to search that area with no results. Plus substantial other evidence exists that the airplane did not explode, crash, alight or otherwise make contact with the water in the area they've been looking for it. SATCOM, an automated system on board the aircraft, and one a very diligent Boeing pilot of my acquaintance says he doesn't know how to turn off, continued sending transmissions. It's a passive system that pings about once an hour, sending what's basically a "ready to transmit" signal but no data links were opened, because the companies involved had not subscribed to that level of service from the satellite operator.

Here's what I have gleaned of the timeline. Times are Malaysian local.

  • 12:41 a.m. Take off
  • 1:07 a.m. The ACARS data transmission system stopped communicating. ACARS is a two-way data transmission system in the cockpit. The pilots can use it to request weather data and the airline will use it to send them connecting flight information, and even to update the flight management system. It automatically transmits some data on phase of flight and things like fuel status and engine performance, so the airline can detect a need for maintenance before it is urgent. It can also be used for communication with ATC, but as far as I know is generally only used with ground controllers to get the complex initial clearance for a flight. It might be used in flight for a complex rerouting, but I don't know. Check the comments to see if one of my more knowledgeable readers does. The ACARS system can be turned off from the cockpit.
  • 1:21 a.m. The crew is 'handed-off' by Malaysian ATC. That is they are told to contact the next controller on a specific frequency. They reply normally to this call, implying that they will comply, but do not call the Vietnam ATC.
  • 1:21 a.m. The transponder is turned off. The transponder is a simple device that works in concert with ATC radar. Before take-off ATC assigns the airplane a four digit code, which the pilot sets on the transponder. When it receives a ping from radar, it sends back a signal encoded with the aircraft altitude and the four digit code. that the pilot has set on the device. The ATC computers match the code with the aircraft type and destination in its flight plan, plus calculate and display a speed based on consecutive returns. If an aircraft does not have a working transponder, ATC may still see the aircraft on radar, but it is a "primary target." The transponder can be turned off from the cockpit. Transponders malfunction pretty frequently, and an aircraft like the B777 probably has two, for backup and to facilitate changing codes without an interruption in radar track.
  • 1:22 a.m. Vietnam ATC expect a check in from the airplane but instead the radar track shows an almost 180 degree turn.
  • 1:38 a.m. Civilian radar lose primary target. Without the positive identification of the transponder reply, controllers only know that their radar is hitting something there. Based on the speed and location, they can sometimes deduce that the target is a train, ship, or flock of birds, and they can be pretty confident that a blip going the speed of an airliner, in the location where an airliner transponder just stopped transmitting, is that airliner. Primary and secondary surveillance radars may have different coverage, so an airplane that could normally be tracked by its transponder signal may not be visible as a primary target.
  • 2:15 a.m Malaysian military radar detects an unknown aircraft, possibly MH370, on a track that suggests it made another turn.
  • 2:30 am Another possible military radar contact with the missing jet. I'm not sure if it shows the jet on the same track or not.
  • 8:11 a.m. Final SATCOM ping received from the aircraft.

The aircraft had about eight hours of fuel on board at the speed it was going, and more if they reduced the power settings. I don't know the radar structure of the airspace they were in to say where they could get to without the aircraft being detected by an agency that would recognize and report its significance.

I don't know what it all means. I have a friend who is livid at the apparent lack of cooperation among the various military agencies who almost certainly have more information on the track of the missing airplane, but don't want to divulge their capabilities to one another. He also suggests that if the SATCOM signals were received by multiple satellites their source location could be triangulated. He also implied that a team of children with expertise at Where's Waldo should be put on the case, but I think the former suggestion was the more serious one.

Here is a link that answers some basic questions I didn't think people would ask, but people have some odd questions about airplanes. Someone asked me if this could be a case of pilot incapacitation, with the autopilot or random chance making those turns. I'd say no. The autopilot wouldn't be programmed to make those turns, and if the autopilot wasn't on, I would expect significant altitude changes. It's an odd incapacitation that would cause you to turn off two separate systems, one fourteen minutes before a normal call to ATC.

This one gives a pretty good explanation of tracking technology, and addresses the question of "how can we apply technology so this can't happen, and why haven't we done so already?"

Because I don't like to think of airplanes crashing if it's not necessary, I imagine that the pilots have stolen the aircraft, kidnapping the passengers. Although probably worse. It sounds like some cellphones were still switched on and even logged into social media accounts. Given the attachment some people have for their phones, it seems unlikely that that many people could be taken alive without anyone managing to get a message of some sort away. Despite my recent rewatching of the television Series LOST, I don't believe that the airplane has been spirited away to a mysterious island guarded by a smoke monster.

The facts that there will be wreckage if an airplane crashes, and that they haven't found wreckage, don't mean that the airplane didn't crash. It's a really BIG ocean, and it takes a long time to search. I liked this picture of Malaysian SAR crews. Of course it's probably posed, but I'm always attracted to shots that depict a group of people engrossed in something, not looking at the camera. It suggests expertise, focus, teamwork, and an important task. I also like the simplicity of the way the women's hijabs work with their flight suits.

I'll give the final word to The Onion, a satirical publication that doesn't know the phrase "too soon."

Update: They've pulled some location information out of the satellite data, but don't have enough satellites receiving the signal to resolve the position ambiguity.

10 comments:

majroj said...

Yes it is posed, if they were on the ground all the headphones would be off (not some), and if they were in the air the noise would necessitate they all wear headphones and mikes.

The whole affair is originating from and interwoven with an area fraught with sectarian, political, criminal, and corruption issues.

Roger the debris field, unless it either did a great forced landing but sank and for some reason couldn't egress survivors (rough seas? But then how to ditch in one piece?) or maybe ended up on dirt like a small island or something.

No telling at this point.

Rhonda said...

wow, 7 hours of satellite pings after last known location. That's a really big area to search.

Anonymous said...

Thanks for the well-written summary.

A Squared said...

but I think the former suggestion was the more serious one.

It's not out of the question, theoretically at least. First off it wouldn't be Triangulation. Triangulation is determining positions by measuring angles (Usually with a theodolite) Determining positions by measuring distances is "trilateration" That is how GPS works (the simple version) Locating the position of the pings wouldn't be either.

If you know the precise time the signal is received at each satellite (not outside the realm of possibility, satellites often have some pretty sophisticated timing gear on board.) And you know the position of the satellites at the time the signal is received (You do, if it's your satellite) YOU have pretty much all you need. You compute the time delay between the reception of the signal and this will give you a hyperbolic "line" of position. If you have other pairs of satellites which received the signal, you can compute other hyperbolas and find the intersection. 3 satellites receiving the same signal will give you 3 pairs, and 3 hyperbolas. This is how LORAN works. Actually LORAN works backwards from this as the signals are traveling the other way, but the principle is the same, it's based on a delay in a received signal.

Whether the signal was received by enough satellites with the timing capabilities necessary is another question, but it's not an impossibility.

Paul M said...

What do you think of this theory? http://keithledgerwood.tumblr.com/post/79838944823/did-malaysian-airlines-370-disappear-using-sia68-sq68 An amateur pilot and aviation geek suggests that MH380 could have planned to intercept another 777 flying for Singapore Airlines from Singapore to Barcelona, and then hide in its secondary radar shadow. The Singapore flight was routing over India and Pakistan, across the North West Frontier with Afghanistan, where it could have peeled off to land somewhere.

It sounds plausible to me, given that special forces used similar cover from ships etc on seaborne missions. I guess it would take some skill though to formation-fly with another airliner where it could see its target but not be seen, even if the other plane's TCAS couldn't detect it.

Aviatrix said...

My guess, based purely on the ease with which ATC say they can distinguish my blip from other blips, versus how close I am to other aircraft, is that it might work when no one expected it. Given the size of these aircraft, I expect there to be something in the radar display software to suppress a double blip for a primary target close enough to a secondary return to be the same aircraft. Once someone suspected the tactic, and went to the tapes, the raw data might be there and show the two separate returns.

On the other hand, the following aircraft might trigger TCAS alarms on the one it was shadowing.

majroj said...

1. To hide in a radar shadow you have to be opposite or exactly aligned with the radar receiver. Not easy with multiple radars, but in this case parts of the route simply don't have ANY radar coverage.

2. I think the pilot of the "cover" plane would be on the radio trying to raise the other plane either to break boredom or determine his/her intentions, which would probably have been monitored.

Paul M said...

There was a suggestion that at some stage MH370 was flying at FL295. The only place of which I am aware that a FL at a mid thousand would be conventional is for the quadrant rule for small aircraft flying VFR outside controlled airspace over the UK, where for collision avoidance you fly at an odd FL in (say - I don't remember exactly) on courses of 1-90, even FL on course of 181-270, and on odd/even plus 500ft on courses of 91-180 and 271-360.

Beyond my expertise, but the suggestion was that FL295 is (a)below the base level for normal airline cruising and (b) being mid-level afforded collision protection because non-one under ATC would be there.

The chap who posed the shadow theory meant, I think, that MH370 would have sat directly above or directly below SIA68. that way its radar return would not have been hidden behind the actual shadow of SIA68 (which of course depends on where the radar station is transmitting from) but would have been indistinguishable from SIA68's return, bearing in mind the squawk coming from it at the same time. He also posits that MH370's TCARs would be able to see SIA68 because it was squawking, but SIA68's TCAR would not be able to see him because his transponder was off or on standby.

It's a great conspiracy theory, but how plausible it is for anyone other than a trained formation aerobatics pilot in a military jet to pull of a stunt like that is another matter.

majroj said...

Yep, like MAVERICK and GOOSE in TOPGUN .

click here

Walt Bates said...

B-777 Capt and LCA Walt Bates

March 21, 2014 at 1:21 pm · Reply

Re the new reports that the course alteration to the west which took the flight off course for the first time PRECEDED by several minutes the copilot’s last and very routine transmission acknowledging their departing Malaysian airspace. This virtually proves to me that at least he was in on this. Whether or not the captain was also complicit could be easily verified by fuel data that Malaysia has not released. In preflight preparation an airline dispatcher will go over weights, winds aloft and forecasted weather at the destination and any alternate airports to calculate what he thinks the fuel burn for the flight will be and then presents his data to the flight’s captain. The captain reviews every assumption made and either approves that fuel or adds some which is done on about 15% of flights. Malaysian Airlines has not released their dispatcher’s calculations so we can not tell if the captain added any fuel. What is known is that the distance to Beijing is almost exactly the same as the distance to Pakistan. The fuel burn, though, would be a good bit greater to Pakistan because of the winds at the time which were out of the west while the Beijing flight would only have had a crosswind. Also he would have had to swing wide to the south or go down to wave-top altitude to avoid numerous radars along India’s south coast. If the captain were planning to fly to Pakistan he would have had to add several thousand pounds of fuel to his dispatcher’s figure which he could do without question or explanation. If Malaysia would release those numbers we could also go back over that same captain’s previous flights to see if he routinely added fuel. A lot of people do that using the old logic that, “The only time you have too much fuel is when you’re on fire”. But I suspect that he rarely did that because as a designated check pilot (LCA) he is supposed to teach the downsides of carrying too much fuel and there are many. I know because that’s exactly what I used to teach. If on flight 370 the captain did add a significant amount of fuel that would lend credence to the thought that he was planning a longer flight than that to Beijing. If he was not in on it and did not add any fuel………well, his copilot would have then been in a fix. Though he could have suggested to the captain that he add some fuel, and that is sometimes done, I doubt that it happened here. The copilot was new to the B-777 and it would be highly irregular for someone in his position to question a fuel decision made by his much more experienced and far higher ranking captain. So, he would have had to make do with what he had. If he made it to Pakistan he would have landed on fumes.

On a separate subject that has always been a thorn in my side………The culpability of the copilot makes the photo showing him going through security with his arms out ironic indeed. Putting the flight crew through security sure didn’t make any difference, did it?