How British satellite company Inmarsat tracked down MH370

The Telegraph ^ | March 24, 2014 | Sophie Curtis

[don-o]

snip

"We looked at the Doppler effect, which is the change in frequency, due to the movement of a satellite in its orbit. What that then gave us was a predicted path for the northerly route and a predicted path the southerly route," explained Chris McLaughlin, senior vice president of external affairs at Inmarsat.

This information was relayed to Malaysian officials by 12 March, but Malaysia's government did not publicly acknowledge it until 15 March, according to the Wall Street Journal. Malaysia began to redirect the search effort that day, to focus on the areas the information described. However, some officials involved with the probe warned that the lost days and wasted resources could impede the investigation.

Meanwhile, Inmarsat's engineers carried out further analysis of the pings and came up with a much more detailed Doppler effect model for the northern and southern paths. By comparing these models with the trajectory of other aircraft on similar routes, they were able to establish an "extraordinary matching" between Inmarsat's predicted path to the south and the readings from other planes on that route.

"By yesterday they were able to definitively say that the plane had undoubtedly taken the southern route," said McLaughlin.

These pings from the satellite – along with assumptions about the plane’s speed – helped Australia and the US National Transportation Safety Board to narrow down the search area to just 3 per cent of the southern corridor on 18 March.

[ProtectOurFreedom]

Geostationary satellites are moving 1.91 miles per second.

[logi_cal869]

I thought these were geostationary satellites. Maybe he misspoke and meant the movement of the aircraft?

I believe so. Makes sense.

Until they produce some evidence I’ll be standing by. It’s hard to believe any of these reports anymore.

I agree. I basically stated the same a week ago. Eventually something elaborated on the 'ping' at the time, but limited in detail.

It shouldn’t have taken this long. That it did seems suspect to me.

Doppler shift, since they compensate for it, should have been the 2nd thing they did after creating the 'arc' based on the 'ping'. You'd think, anyway.

Definitely odd that it took so long. However, much more plausible than overflying India to Pakistan with impunity and/or undetected...

[Jaded]

There is a Monty Python sketch in here somewhere.

[Meet the New Boss]

Geostationary satellites are moving 1.91 miles per second.

You're confusing orbital velocity with movement relative to the surface of the earth. That orbital velocity is designed to match the rotation of the earth so that, as much as possible, the satellite does not move relative to the surface of earth.

[gr8eman]

They are geostationary. Normally Low Earth Orbiting sats can track ground movement with radar using Doppler. Geostationary are 33,000 nautical miles out so this story may be wrong.

[Buckeye McFrog]

After this incident I am sure that they are going to beef up the system of satellite “pinging” to track aircraft. And probably remove the “off” button from all transponders.

[Political Junkie Too]

There is a Monty Python sketch in here somewhere.

Close... :-)

"We looked at the Doppler effect.

-PJ

[Jaded]

This story has served its purpose as a diversion. Time to move along. Don’t question the authorities... they KNOW what is best for you.

[Timocrat]

If the plane went into the ocean at a high velocity and a high impact angle,

If the plane runs out of fuel does it "glide" for a certain period of time or nose dive in ?

[Jaded]

This story has served its purpose as a diversion. Time to move along. Don’t question the authorities... they KNOW what is best for you.

[bert]

Plus, Richard Halibutron’s junk sailed into the ocean from China and was never herd from again.

There is definitely something out there

[gr8eman]

Inmarsats are comms satellites with focused spot beams. Wouldn;t that have to have been communicating with the plane to detect Doppler shift? If they had an orbital autotrack function that uses Doppler shift for orbital correction, the signal would be focused on a beacon with a known lat, long, and altitude. I thought satellites used star patterns in concert with ground beacons for navigation control.
No way an Inmarsat bird could “track” an object without common communications between the two objects IMO! Am I missing something here?

[LonePalm]

I do happen to have a bit of expertise in this area. I have a patent in Electronic Warfare and worked for two and a half years at the Joint Satellite Engineering Center before it moved to APG, Maryland.

Signal Doppler can be caused by motion of the transmitter, motion of the receiver, or both. There would be little to no Doppler shift with regards to a satellite in geosynchronous orbit. Assuming that the satellite was near the same longitude there would only be Doppler shift if the plane were moving up or down relative to the surface of the earth, and hence, the satellite. If the geosynch satellite was near the horizon, a Doppler shift would only be generated based on the East-West motion of the aircraft. If the aircraft was on a mostly North-South track, as has been proposed, the Doppler shift would be VERY small.

If the satellite was in low earth orbit you could get significant up or down Doppler shift depending on positions and relative motion of the satellite and the aircraft. Doppler shift would be the greatest if they were on or near the same track and less or none if the tracks were perpendicular.

If the satellite had the ability to determine the bearing of the signal (unlikely) then you could use target motion analysis to generate a series of likely tracks (and general position) depending on the assumed speed of the aircraft.

Hope this helps.

Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)

[tet68]

Right, Malasyan Triangle. It’s out there...

[ExNewsExSpook]

Assuming the pilot doesn’t push the stick “over” it will glide for miles, depending on your starting altitude and sink rate. The crew of a Canadian 767 had to dead-stick their jet into an abandoned CFAB base back in 1983, due to a malfunctioning fuel management system and poor “by hand” calculations. As a result, they took off with barely half the fuel needed for a flight from Ottawa to Edmonton.

The incident has become known as the Gimli glider, after the former Canadian AFB facility where they landed. It was also made into a fairly entertaining TV movie starring William Devane.

http://hawaii.hawaii.edu/math/Courses/Math100/Chapter1/Extra/CanFlt143.htm

Of course, the pilots of the Canadian 767 were trying to get their aircraft—and its passengers—on the ground in one piece, unlike the Malaysian pilot who flew that 777 into the Indian Ocean.

[chris37]

So what they are saying, in effect, is that they have zero idea where it actually is and zero idea what actually happened to it.

Someone alert CNN so they can go wall to wall with this for the next 200 years...

[Cyber Liberty]

Maybe I’m being too much of a stickler here, but shouldn’t we wait until the plane is actually found before we start bragging about the technology’s success?

Just a thought.

[Timocrat]

Of course, the pilots of the Canadian 767 were trying to get their aircraft—and its passengers—on the ground in one piece, unlike the Malaysian pilot who flew that 777 into the Indian Ocean

Do you happen to know if the Auto pilot would automatically assume a glide path if the crew were comatose/dead and not in control of the aircraft. ?

[steve86]

Presumably there is also a relativity effect when measuring tiny differences in elapsed time at 22,000 miles above the earth compared to an aircraft flying 7 miles above the earth. I don’t know whether it is big enough to be relevant

It is definitely significant enough to be included in hand held GPS units -- error would increase significantly if it weren't.

[pnz1]

This is so confusing to me..