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The overlooked Malaysian Flight 370 communications system


Much conjecture has been reported on what happened to missing Malaysian Flight 370, the 227 passengers and 12 crew on board. The Wall Street Journal and the New York Times are in a wonderful race to outwit the other in investigative reporting – a great relief to their ad nauseum race to write the most political theatre that America doesn’t care about.

But no news media has reported on the “other significant communications device” which was on board the aircraft, and may have been turned off during the disappearance, until this report. Controller Pilot Data Link Communications (CPDLC) is a two-way data-link system by which air traffic controllers can transmit messages to the pilot without the use of voice communications.

“We use CPDLC when we are not flying in a radar environment,” said Harty, a veteran commercial airline pilot first introduced in part one of this series of reports. “Once Flight 370 got 200 miles off shore, it entered a non-radar radar environment. Radar is only good that far out.”

The CPDLC message is displayed on a flight deck visual display and is an essential element of the Automatic Dependent Surveillance (ADS) which was pioneered by Boeing and adopted early by Airbus. The ADS is a surveillance technique in which aircraft automatically provide data from on-board navigation and position-fixing systems, including aircraft identification, four-dimensional position and other data. It broadcasts position, vector and other information for use by other aircraft, and by ground facilities.

Malaysian Air might have installed ADS, but that has not yet been determined. It would have had CPDLC on board.

“Once you’re offshore and out of radar range you are relying on position reports. The CPDLC will give you altitude, air speed, latitude and longitude. The news media say ‘he turned off his transponders,’ okay, the transponders only works in a radar environment.”

Transponders perform critical location functions in our air traffic control system as they identify the aircraft and its altitude on the radar screen and enhance the return signal, which makes the aircraft easier to identify on the radar screen. The Boeing 777 would have had two transponders.

“But, since the airplane was out of radar range, the CPDLC would normally send the position report,” added Harty, who assumes that device was also turned off. “When I’m 250 miles off the coast of Nova Scotia, out of radar range and headed for France, I use the CPDLC. With that baby turned on, I can read my newspaper, and I’m flyin’ on auto-pilot anyway.”

The standard method of communication between an air traffic controller and a pilot is voice radio, using either VHF bands (very high frequency) for line-of-sight communication or HF (high frequency) bands for long-distance communication. One of the major problems with voice radio communications is that all pilots being handled by a particular controller are tuned to the same frequency. So, as the number of flights increases, the chances that one pilot will accidentally override another increases, hence the invention of CPDLC and ADS.

Let us assume for this article, that there were two passengers carrying fake passports, the two pilots had their own quirky idiosyncrasies such as making a flight simulator in one’s basement, the plane could have flown on autopilot for up to seven hours, the search area is greater than 2,000 miles across, and it could span from Pakistan to Northern Australia. All that’s a given, if you believe in speculation and few facts. But with the aid of our seasoned airline pilot’s knowledge, let’s look at what could have happened from a technical, or pilot’s point of view. It is assumed that Flight 370’s transponders went silent, because someone turned them off.

But the other (unproven) assumption is that the aircraft continued to transmit data via the Aircraft Communications and Reporting System (ACARS). That’s important because if a catastrophic failure had caused the transponders to stop transmitting, it is very unlikely that ACARS would have continued transmitting.

Absent a catastrophic failure, it is hard to imagine how the two transponder switches could both be turned off accidently. There are some interesting parallels to the story of the missing Flight 370 if Flight 370 really existed; (see part one). One is Air France 447 which crashed into the Atlantic in 2009 and the other is Payne Stewart’s crash.

“Both are dependent on one of two additional factors - intent or non-intent,” claims Harty. In other words, if there is no intent and it is the Payne Stewart version, and they have the flight plan programmed into auto-pilot, then the airplane was flying on its own. “There could be zigzags in the flight plan because of the goofy Chinese airspace in that region which requires a less than straight flight path,” Harty added. “But if it’s a Payne Stewart scenario, then we have to look at those facts and similarities.”


Payne Stewart, the highly successful professional golfer, died – with two pilots and three other passengers - in an airplane crash in South Dakota in1999. Investigators determined the cause was incapacitation of the flight crewmembers as a result of their failure to receive supplemental oxygen following a loss of cabin pressurization. Between the last communication between the aircraft and air traffic control and the aircraft's final descent, the aircraft was reportedly flying at times in excess of 46,000 feet (the service ceiling is about 45,000 feet). Malaysian Flight 370 is alleged to have risen, briefly, to that same elevation.

“Payne Stewart left a golf tournament in Florida and was headed toward Chicago when a pressurization leak helped the plane rise to a high elevation rendering them unconscious,” said Harty. “So, they were passed out because of hypoxia but on auto-pilot for a few hours. People were trying to get ahold of them by radio. People were concerned that they might have to shoot the plane down before it flamed out over Chicago.”

When an Air Force F-16 pulled up alongside of Stewart’s Learjet, the F-16 pilot reported that both engines were operating on the Learjet and that the cockpit windows were obscured by condensation or frost. Four other F-16s observed the flight at various times, including the final descent and impact of the aircraft.

“Stewart’s plane ended up burning a hole in South Dakota, near Aberdeen,” said Harty. “So, that was the scenario that first came to mind in Malaysian Flight 370. It was either an insidious pressurization problem, or a rapid but not insidious decompression problem. When you start seeing zigzag turns you may have had a slumping pilot hit a heading switch. But it appears more likely someone did it on purpose.”


Flight 447 took off from Rio, bound for Paris, on the last day of May 2009. On June 1, the plane slammed into the Atlantic resulting in the deaths of all 216 passengers and 12 aircrew without a Mayday call, or a witness, or even a trace on radar. One difference between Flight 370 and Flight 447 was that 447’s CPDLC was working. Within a few days debris was located but the black boxes and 104 bodies sunk to 13,000 feet and were not found for two years. While still flying, crews of pilots rotated seats because of the long flight. The auto-pilot disengaged and the plane began to roll to one side. The aircraft was oriented nose-up but descending steeply. The engine stall warning activated a few times.

Human error was given as the cause of the crash. In the pilots’ defense, the Airbus design has created erroneous airspeed readouts quite often, but it is up to the pilots to react appropriately.

“With their CPDLC, 447 was able to give a position report several minutes before they decided to top a thunderstorm they couldn’t top,” Harty said. “They got blown out the top and the co-pilot was pullin’ back, stallin’ the airplane out, and then flat pancake spins it into the ocean. Idiot. But they did have a good place to look.”

If making Flight 370 disappear was intentional, what are the intentions? If it’s a crazy pilot who wants to kill his passengers, then maybe he did zigzag all over the place.

“If he was Doctor Evil and he wanted to steal a plane and land on Cocopupuphet Island, take the people off the jet and load it with a bomb bound for Kabul, then you have your intent,” said Harty.

The pilots of Flight 370 could have set the auto-pilot to take the airplane to a specific altitude and on a specific course. Some say that Pakistan has the airplane, but the Pakis say ‘no,’ that someone would have seen it, most likely on radar. However, you can fly the 777 at an altitude of fifty feet over average terrain. You would use a lot of fuel, but it can be flown under radar.

“If I’m gonna sneak up and bomb a city, I’m going to fly high to save fuel. Then about 300 miles out, I’m gonna drop down to the deck and fly at fifty feet for the last 300 miles. I’ll be under the radar.”

Malaysia and neighboring Indonesia have Islamist fundamentalists and al-Qaida types as residents, and Petronas Towers in Kuala Lumpur was the tallest building in the world until 2004; there was a Malaysian shoe bomb plot; and it was among communities in Thailand and Malaysia that Khalid Sheikh Mohammed first planned the September 11 attacks on New York and Washington.

But if the intent of making Flight 370 disappear was terrorism, the moment it disappeared it lost its ability to terrorize someone. If the idea is to land somewhere in Asia or the Indian Ocean, the Boeing 777 would have required a large runway, and friendly air traffic controllers.

“I can land my Airbus 330 in 6-to-7,000 feet with a tight sphincter,” said Harty. “But I can’t take off in that space unless I’m completely empty, including fuel and passengers. For the 777, they’re not getting it out in 6-to-7,000 feet, they would need 7-to-8,000 feet.”

I would have thought the longer the search went, the greater the likelihood of a nefarious plan, but Harty corrected me.

“What I believe happened is that I don’t know. The longer it goes, the less likely you’ll find it. If it was a Payne Stewart scenario, you should be able to find it. If it was intentional, that is a vast Indian Ocean out there. You may never find it.

“In a decade or so, we might find that it went down in a smokin’ hole in one of those equally vast jungles. Someone will find a silver back gorilla wearin’ a flight attendant uniform, eating emergency rations next to a fuselage.”

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