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March 13, 2014

Malaysia Airlines Flight 370 (MH370)

So, I've been following this crazy missing airplane fairly closely for the last 5-6 days. I think that, at this point, they have a pretty good idea about where it went down in the Indian Ocean. The United States is sending a boat/ship to an unspecified location in the Indian Ocean right now. The trick is that ACARS was constantly pinging a satellite with the location of the airplane for about 5 hours after the flight crew turned off ACARS and the transponder for whatever reason.

So, they have a pretty good idea where this plane went down. What's hard to understand is why?

They say that the simplest explanation is usually the right one, but there's no simple explanation for this at all. Not even close.

A Malaysian Airlines Boeing 777-2H6ER ( 9M-MRO ) departed KUL bound for PEK.

The plane took off shortly after midnight local time (MYT) from Kuala Lumpur heading to Bejing airport. About an hour into the flight, they left Malaysian airspace, and would then be handed over to Vietnam airspace flight controllers. They said "Goodnight" to the air traffic controllers in Malaysia, but never said a word to the flight controllers in Vietnam.

"Two U.S. officials tell ABC News the U.S. believes that the shutdown of two communication systems happened separately on Malaysia Airlines Flight 370. One source said this indicates the plane did not come out of the sky because of a catastrophic failure.

The data reporting system, they believe, was shut down 1:07 a.m. The transponder -- which transmits location and altitude -- shut down at 1:21 a.m."


Flightradar has data till 1:21 a.m., meaning ADS-B (Automatic dependent surveillance-broadcast) was transmitting until then.


So, they shut off the ACARS data reporting system at 1:07 a.m., then shut down the transponder at 1:21 a.m., 14 minutes later.

Chinese military radar reported plane showing steep descent after transponder turned off, heading change from 020 to 330

Either the ACARS Data Reporting System went down at 1:07 a.m., or the last ACARS message was sent/received at 1:07 am. However, it's possible that the ACARS system could still be operating, but because messages are sent at intermittent intervals, it may have been working but had nothing to report?

But ACAR's transmissions are not continuous - so this does not mean ACARS shut down at 1:07 a.m., just that this was the last time it sent anything.

But the SATCOM network interrogations pings continued, even though ACARS data was not being transmitted. This suggests that ACARS was somehow disabled in some way other than by disabling SATCOM.

The SATCOM/VHF/HF radios are all discrete avionics blocks and are separate from the avionics blocks generating the message traffic on the radio signals. The radios aren't dumb signal-forward devices, they have intelligent modems that build the digital link over the radio wave. Think the PHY device on a network card or the optical transceiver module in a router or switch. The data messaging level is one step back, you push the message onto the radio's input channel and it encodes it into a modulated analog signal and sends it on over the antenna.

If you disable or fail the block that generates the ACARS messages, or the transponder block, and the SATCOM block remains powered and operational, you would get the situation where the SATCOM keep-alive signals are present, but no data can flow.

The CBs for SATCOM are not on the flight deck but are located down below in the EE bay (electronics equipment bay).

To cut ACARS you need to access the electronics bay behind and under the cockpit.

Turning off transponders, and VHF Data Link radios for the ACARS system is more straight forward through the control tuning panel. But shutting down the Satellite communication is not as straight forward and may have not been turned off.

ACARS and SATCOM are two different "boxes". ACARS compiles information, and then sends it with SATCOM (in this case). Pulling the breaker(s) on either one would stop ACARS transmissions but I'm pretty sure you need to get to the electronics bay in either case.

On PPRuNe a 777 pilot mentioned that you can simply turn on/off various ACARS broadcasting modes (VHF/HF/SATCOM) from the computer right there in the cockpit

But you need to pull the CB in the EE bay to stop SATCOM from pinging.

Quoting captainx (Reply 136):
No. The circuit breakers are located in the E/E bay."

Only the SATCOM, VHF/HF are in the cockpit.


Instead, they turned off the transponder, turned off ACARS, descended 3,000 ft, and turned west, flying back across the Malaysian peninsula undetected on a dark moonless night. The military primary radar tracked them, but wasn't sure what plane they were seeing, as the transponder had been turned off.

They did not turn off ACARS 10 minutes before the transponder - on this ship the ACARS data was from the engines and it only transmits 'on occasion'. The last ACARS transmission happened to be 10 minutes before the transponder stopped.

The SATCOM pings are NOT ACARS data. ACARS does use satellite communications when out of VHF range. But the SATCOM is the transmitter - and it is used for lots of stuff. The SATCOM 'reportedly' sent keep alive pings every hours or so to the satellites.

Disabling the transmission of ACARS over SATCOM from the flight computer, I assume, would not power down the actual SATCOM hardware, meaning it would still be sending keep-alive packets to the satellites.

After they crossed the Malaysian peninsula, and the Strait of Malacca, then they were over open water, and flew for 5 more hours. The last ping from MH370 came at least 5 hours after vanishing, with the last ping indicating that they were at cruising altitude over water. Each ping that came from the 777's SATCOM included GPS coordinates, altitude, and speed. We know exactly where MH370 last pinged Inmarsat's satellite constellation, and a ship from the US Navy is sending a vessel there right now.

We know this because the plane kept pinging the satellites with the plane's location as it flew thousands of miles off course, eventually running out of fuel and crashing into the Indian Ocean.

Best guess at this point is pilot suicide. Possibly, the reason that the plane flew for 5 hours after turning off the transponder and the ACARS was so that the CVR and FDR would write over the initial data from the time of the hijacking. Maybe this was a scam tot ry to collect life insurance for the pilot or the co-pilot.

Malaysia Air only uses one pilot and one copilot for this flight. The pilot had a flight simulator in his home and had been flying the Boeing 777 for over 15 years and knew this route extensively.

Probably the pilot locked the copilot out of the cockpit when he went to the bathroom. Depressurized the cabin, causing hypnoxia in the plane cabin. The pilot would have been using an oxygen mask. And then, why he chose to fly for 5 more hours is pretty much anyone's guess.

It's possible, even probable, that the pilot also turned off the flight data recorder and the cockpit voice recorder. So, we may never know what really happened, even if we find the plane.

Although some of the Boeing 777-200 planes have satellite phones for the passengers on the plane, no phone calls were made. This could be because this plane didn't have the satellite phones, or because they were turned off.

Posted by Rob Kiser on March 13, 2014 at 11:53 PM


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