The week of the third anniversary of the disappearance of Malaysia Airlines flight MH370 in the Indian Ocean, we still haven't found the plane. Authorities suspended the search earlier this year, according to the Guardian, and unfortunately, may not be looking for the plane any longer.
A report obtained by Gizmodo seems to offer a pair of impact locations though, as well as a method that could be used to locate similar plane crashes in the future. Scientist Usama Kadri, an applied mathematician and engineer affiliated with MIT and Cardiff University, recently presented the Australian Transport Safety Bureau with a fairly new, esoteric way of analysing the deep sound waves travelling through the water, called acoustic gravity wave theory.
"Researchers at the beginning looked at acoustic signals, but acoustic gravity waves are low frequency, lower than the frequencies people originally looked at," Kadri told Gizmodo.
Malaysian Airlines flight MH370 crashed some time on the morning of 8 March 2014, local time. The accident presumably took all 239 lives on board, and searches to find the plane and offer closure to the victims have turned up mostly fruitless, aside from some debris.
Acoustic gravity wave theory says we might be able to locate the plane from specific aspects of the underwater sound of its impact. The theory looks at the way those low frequency (deepest note) sound waves travel through the water when the effects of gravity and the shape of the ocean floor are taken into account. When MH370 hit the water, it likely created vibrations that travelled far faster than the speed of sound in air, upwards of 4800km/h through the ocean.
Kadri analysed data in a set of hydrophones, underwater microphones, and looked for signals occurring after the last handshake, or the last time satellite data picked up the plane's signals. He found several hits, and acoustic gravity wave theory allowed his team to determine the distance as well as direction of some waves. Most of the data collected by the team was ruled as seismic activity, but sound from a pair of locations off the coast of Australia outside the so-called "seventh arc", a boundary that helped refine the search for the plane based on it where it would have run out of fuel, could not be explained by tectonic activity alone, according to data shared with Gizmodo by Kadri.
Possible impacts predicted by Kadri (Image: Kadri et al)
"But we're not claiming that we found the aeroplane," said Kadri. "We're saying we have a method of finding impacting objects."
The signals offer tantalising hints to MH370's location. Using the data points, Kadri thinks he's localised the source of the sound to a circle with a 100km radius. But there are plenty of caveats. The signal came an hour or so, rather than five minutes, after the last handshake, which means the plane would have had to have flown for a while without pinging satellites before the impact.
"Unfortunately these locations are not consistent with the results from the satellite communication data and the aircraft performance (endurance and range) analysis," Daniel O'Malley, a spokesperson for the ATSB, told Gizmodo via email. "Nevertheless, [Kadri's] analysis is being retained as part of the material that may contribute to any future efforts towards locating the aircraft."
Others think Kadri's method could be a reasonable way to spot the impact. "I think Usama is doing a very wonderful job," Ali Abdolali, postdoctoral researcher from the University of Delaware told Gizmodo. "He has distinguished the differences between local earthquakes and other sources of acoustic gravity wave signals and found one signal which they didn't know what the source was. And that might be the aeroplane. That would be possible."
Abdolali did point out not to take the results as truth yet, and that an accurate location would likely require a more in-depth modelling of the ocean floor. "They need to go to a numerical model," he said, "put the aeroplane on the surface, and then run the model. That takes lots of time on a big supercomputer."
Regardless, with the investigation closed it's unlikely the 1500m deep water at these locations will be explored in the near future. Kadri doesn't want to get anyone's hopes up. "Seeing the families desperately looking for answers put things into a very sensitive context."
Hopefully the method will be tweaked, better seafloor models will become available, and acoustic gravity wave analysis could be of more help to authorities with problems like these in the future.