Wednesday, March 19, 2014

Thoughts and Perspective on MH 370

I remain unconvinced of the terrorism angle, or some intentional behavior on the part of the crew to hijack their own plane.

I've had the honor of having two articles posted on the CNN Opinion page, 6 days apart. In the first,  http://www.cnn.com/2014/03/10/opinion/palmer-malaysia-aircraft-air-france/, published two days after the crash, the assumed location and search area was the Gulf of Thailand.

I calculated the search area (shore to shore distance x glide range) to be about the size of Pennsylvania, an analogy that was since widely used. It's a large area, with an average depth of about 150 feet. A difficult search, but I had confidence that the airplane would surely be found.

I made the assertion that the lack of an immediate distress call didn't necessarily mean foul play. I cited the aviator's priorities in that article: aviate, navigate, and communicate , in that order, and that has since been repeated by numerous other pilots interviewed, including famed aviation author and TWA pilot Barry Shiff. Shiff stated "If you have a serious problem aboard a jetliner like a fire, one thing you're going to want to do is get on the ground as soon as possible and turn back towards Malaysia, towards a large airport. It's the first thing I would do. The most imperative thing is to take care of that fire. The last thing you're going to do is communicate unless you have the time to do it because no one on the ground can help you."   To look back at a real-life example, the AF447 pilots knew they were having trouble for 4 1/2 minutes, but they were too busy trying to control the airplane to make a distress call.

It also appears that the trouble may have started with some incident that took out the communications capability, making a distress call, even if attempted, unsuccessful.

Media reports today (3/18) report that the transponder stopped working before the now famous "all right, good night" final words. The inference, and it's often reported as much stronger than an inference, is that the pilots shut it off before saying good night to the Malaysian controller.

By the way, the words "all right, good night" are absolutely routine. Every pilot that news reporters have asked about these final words have said the same thing. Yet for some reason, the reporters seem to believe that it was something more sinister.

If a transponder fails, usually the only indication is the controller asking the pilots to reset it. There is no indication in the cockpit of when the transponder is working or not, just an ON switch. The transponder could well have failed as a result of some mechanical malfunction going on in the equipment bay below them, and they never knew about it.

The left turn observed on radar, after this time could have been initiated, as the New York Times reported, by programming the change into the flight managment computer. This would be a quick and easy way to head to an emergency diversion alternate airport, several have been suggested including the 13000 foot runway at Palau Langkawi, with an approach over water and no obstacles.(google maps link). It could also have been inserted with a single push of the Heading Select button, flown by hand, or possibly even a result of the autopilot failing. There is no publicly revealed proof that the method used was to intentionally enter a new TO waypoint into the airplanes' flight management system. Even if it did, it doesn't reveal the reason - ill intent, or emergency diversion.

In the second article, http://www.cnn.com/2014/03/16/opinion/palmer-malaysia-flight-370/, I made the point that the recently revealed strange altitude path, ranging from the original cruise altitude to a reported 45,000 feet down to 23,000 feet, followed by another climb, was not necessarily the work of a "skilled aviator" but could very well be the result of the airplane flying by itself, crew incapacitated, with the autopilot off. Afterall, what "skilled aviator" can't hold altitude within 20,000 feet?

In light of the westerly turn, the possible locations have grown from the size of Pennsylvania to all of North America (my estimation at 8.2 million sq nautical miles), the search area, being somewhat smaller than that at 2.9 million sq miles.

In contrast to the average depth of the Gulf of Thailand at 150 feet (maximum 260), the average  depth of the Indian Ocean is over 12,000 feet, with maximum depth values of more than twice that value.  The breadth and depth of the possible locations is a concept few have managed to grasp. This is evidenced by statements wondering how a 777 can "just disappear."

AF447 Vertical Stabilizer
One should realize that a B-777 is not going to be floating on top of the waves for someone to find. Looking back at previous water landings, and there haven't been many, yields a possible range of what will be left:

In the case of AF447, which impacted the water at a vertical speed of 109 knots, the airplane was completely and utterly destroyed. Some floating debris remained, the largest being the airplane's vertical stabilizer.The debris was scattered subject to 5 days of drifting before it was located.
AF447 Surface Debris
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In the case of AF447, investigators had a pretty good idea where to look. The initial search area was about 5,000 square nautical miles. It took 5 days to find the first bit of floating debris, and two years to find the remains spread across the ocean floor below.

The current 2.97 million square mile search area for MH370 is 594 times larger than that for AF447!
For an interesting presentation on the search see this presentation.

The USAirways flight 1549, "miracle on the Hudson" aircraft remained partially afloat for some time, but would not likely have remained so for days.
Had an airplane remained intact on touchdown, which would have required a pilot directed ditching, there may not be anything left  of the aircraft on the surface, except rafts of any possible survivors.


This brings us to the pingers, those acoustic beacons to help locate the airplane's flight recorders. They activate when submerged.

According to the AF447 investigation report, the underwater locator beacons (aka pingers) have a "maximum range" of about 2000 meters (6500 feet). This means that considering the 12000+ depth in most of the Indian Ocean, searchers will need to have underwater listening devices (subs, or sensors) more than 6000 feet down and in a tight search grid.


The water pressure at 12,000 is over 5400 psi. The AF447 recorders survived that depth, designed to withstand up to 20,000 feet, but the locator beacons were not operational when recovered, probably damaged in the crash.

By the way, the wiki article on maximum sub depth states "Modern nuclear attack submarines like the American Seawolf class are estimated to have a test depth of 490 m (1,600 ft)." Their listening capability is probably pretty darn good, but still implies the necessity for a very tight search grid on an extremely wide area.

2000m is about 1 nautical mile. With the reported 2.5 million square miles search area, a back-of-the-napkin calculation equates to about a million miles of deep water listening. The tow rate is very slow, a couple of knots, let's say six knots. That's 167,000 search hours (19 years) for a single vessel. Oh, and the pingers only ping for 30 days. In the three weeks remaining for the pingers, if it's in the search area, that would require over 300 deep-listener equipped search vessels going 24/7. There aren't anywhere near that many.

There many mysteries surrounding this flight due to the utter lack of reliable data. The location of the aircraft and its recorders is absolutely essential to unraveling them. The sad fact, however, is that the task is so difficult that it is very possible the remains of the airplane will never be found and it will join the ranks of Amelia Earhart (1937), Northwest Airlines 2501 (1950), Pan American Airways Flight 7 (1957), and others.

1 comment:

Bill Palmer: flybywire said...

For another viewpoint be sure to see Karlene Petitt's blog: http://karlenepetitt.blogspot.nl/2014/03/pilot-in-jumpseat-of-mh370.html