The UK company responsible for confirming that flight MH370 crashed into the southern Indian Ocean has explained why it took two weeks for their initial suspicions to be verified.
Although the communication systems on the Malaysia Airlines craft were switched off, Inmarsat's satellites continued to receive hourly 'pings' from the plane.
These pings are sent from a ground station to a satellite 22,000 miles above the Earth - then on to the plane. The plane then automatically sends a ping back to the satellite and down to the ground station.
By measuring the amount of time it took for pings to be sent and returned and looking at comparisons to other flight data, scientists at Inmarsat were able to spot a pattern.
They believed the plane flew for at least five hours along one of two 'corridors' - one arcing north and the other south.
This information came to light on March 11 but was not publicly acknowledged by the Malaysians until March 15, when the search effort moved to the Indian Ocean.
Since then Inmarsat have worked with more data from other Malaysia Airlines flights to refine their measurements.
They also brought in Boeing and ran their calculations past other UK experts.
This left them confident enough to confirm that it could only have been travelling along the southern corridor - and that because there was nowhere for it to land on that path, it would have eventually run out of fuel and come down in the Indian Ocean.
Malaysian Prime Minister Najib Razak said Inmarsat had employed a technique never used before.
Chris McLoughlin, senior vice president of Inmarsat, told Sky News that some guesswork had to be involved.
"We don't know whether the plane stayed at a constant speed, we don't know whether its headings changed subsequently," he said.
"We applied the autopilot speeds - about 350 knots. We applied what we knew about the fuel and range of the aircraft to hit the series of ping information we had.
"Normally you'd want to triangulate, often you'd have GPS. But because aircraft in that region are not mandated to send out signals of their location we were working from blind, so this is very much a unique approach - the first time it's been done."
Mr McLoughlin believes all commercial planes should now be fitted with existing technology provided by Inmarsat and other satellite companies that would prevent prolonged searches like this unfolding in future.
"Every commercial aircraft could be tracked, if not tomorrow then by the end of next week," he said.
"Just imagine if the data had been coming off the plane for a couple of hours while it was missing.
"There is even an outside possibility, if it had been realised quickly enough, that interceptor jets could have been sent up to see what was going on.
"Many airlines choose to do it already; over the north Atlantic it's mandated. It needs to be mandated everywhere and it could be delivered tomorrow.
"It would be a quick win that would at least make some sense of this. It sometimes takes a major tragedy to move things."
The families of the 239 people on board flight MH370 were told on Monday their loved ones would not return home.
The search for remnants of the plane continues.
Aided by knowledge of how much fuel was on board, Inmarsat say the craft's last recorded position was in the middle of the Indian Ocean, west of Perth.
The search effort becomes more difficult every day as currents shift debris away from their original position.
Debris could have drifted 24 miles each day.
The area of ocean where the search is centred is 3,500 metres deep (11,500ft) - and the black box which will provide answers could be at the bottom.