MH370 Search Update – Mar 18, 2018

Recent Activity

Seabed Constructor, the vessel operated by Ocean Infinity to scan the seabed in search of MH370, is returning to port in Fremantle, Western Australia, to refuel, change crews, and resupply. Constructor is completing the second of three or four swings, each swing lasting about six weeks. So far, there have been no promising sonar “contacts” that might represent the debris field of the missing aircraft.

There remains about 3,000 sq km of seabed to search in the area that the ATSB and CSIRO designated as a priority. After that, the extended search area along the 7th arc would require scanning about 46,600 sq km to reach north to around 29S latitude if the width of the search was 25 NM on either side of the 7th arc. That will require more than one additional swing to complete. In fact, it could prove challenging to complete with even two additional swings, depending on the weather and how well the eight autonomous underwater vehicles (AUVs) perform. Although not publicly stated, there are indications are that at least one of the AUVs is having technical problems.

What We Know So Far

Any scenario that leads to a particular location (a “warm spot”) is based on a set of assumptions, and the failure to find the debris field in proximity to this location means that one or more of those assumptions are false. So we can be fairly certain that the large, blurry objects seen in the French satellite images were not from MH370, as the corresponding impact locations calculated by CSIRO were searched without success. Also searched was the warm spot that was calculated by assuming that the aircraft flew until fuel exhaustion on a path towards the South Pole. Unless an interesting contact was found but not yet disclosed, this scenario also can be dismissed.

In the coming weeks, other scenarios will be searched, including the impact site near 30S latitude that is based on two floating debris fields that were spotted during the aerial surveillance, and discussed at length in a previous post.

Reasons Why the Debris Field Has Not Yet Been Found

Although the area already scanned by Seabed Constructor was designated the highest probability by the ATSB and CSIRO, there are reasons why endpoints outside of this area are still possible.

A descent at 18:40 followed by a holding pattern, excursion, or other “loiter” before the turn to the south could mean the plane impacted along the 7th arc to the north of the priority area that has been searched. The last radar target was captured at 18:22, and after 18:28, the next ping arc derived from the BTO data is known at 19:41. There is simply no way to be sure of the path of the plane during this interval.

A shift in oscillator frequency of the satellite data unit (SDU) of the SATCOM, which would change the value of the fixed frequency bias (FFB) that is used to convert the location and speed data into a BFO that can be compared with the measured BFO values. In a nutshell, if the FFB shifted by +7 Hz after the power up at 18:25, endpoints as far north as 27S are allowed by the BTO and BFO data. It turns out there is an effect called “retrace” that causes oscillators that are powered down, cooled, and powered up to shift in frequency, and there are indications that a retrace shift of about -4 Hz occurred while 9M-MRO was on the ground at KLIA before the MH370 flight. A similar shift, but in the opposite direction (up) might have occurred due to the inflight power cycling.

Pilot inputs after 19:41 might have altered the path. The continuous, smooth progression of the BTO and BFO data suggests automated flight with few or no pilot inputs until fuel exhaustion. However, there is a remote possibility that the smooth progression of values was produced by a more complicated path that by chance replicated the simplest of paths.

There is also the possibility that the previous search was as the correct latitude along the 7th arc, but the width of +/- 25 NM from the 7th arc was not sufficient. The final two BFO values indicate a steep, increasing descent that if continued would mean the plane impacted close to the 7th arc. The debris is also consistent with a high-energy impact. However, it is possible, albeit unlikely, that a skilled pilot carefully recovered from the high-speed descent, regained altitude, and glided for some distance beyond 25 NM.

Although some of the area north of the priority search area was searched by aerial surveillance in the weeks following the disappearance, the search area was large and the coverage was spread thin. Also, some debris was seen from air, but never recovered due to the distance of ships supporting the search effort.

Simulation of Seabed Constructor’s Search Pattern

Finally, Richard Cole, who has carefully been tracking and analyzing the search patterns of Seabed Constructor, has produced a short video which shows the path of the vessel and how it relates to the launch and recovery of the AUVs. Richard is quite talented at extracting a lot of information from small amounts of data, and this video, like all his work, is commendable.