Safety Investigation Report 2018:1 Factual Information/1.1/1.1.5
SAFETY INVESTIGATION REPORT MH370 (9M-MRO)
1.1.5 Detection of Hand Phone Signal
A Telco service provider in an interview with the RMP confirmed a signal “hit”occurred at 0152:27 MYT on 08 March 2014, coming from the mobile phone tower (LBS Location Base station) at Bandar Baru Farlim Penang. The signal “hit” however did not record any communication except to confirm that it wasin the ON mode signal related to the “hit”. The phone number xxxxxxx was later traced to that registered under the FO. This was supported by the RMP’s report.
To ascertain the probability of making calls inside an aircraft from different altitudes, a reconstructed flight using a King Air 350 over the said area and during the same time when the signal “hit” happened was carried out shortly after the disappearance of MH370. The flight was conducted from an altitude of 24,000 ft with step descents every 4,000 ft until 8,000 ft. The next descent was to 5,000 ft but at 1,000 ft interval. An expert from a Telco service provider conducted the test using three different brands of phone and related equipment that were carried on board the King Air 350. Test call will be automatically answered by the server in the event of connectivity.
In summary, during the tests, it was found that it was difficult to maintain successful call connectivity above 8,000 ft. However, one brand of phone was able to make a call at 20,000 ft. Only one cell phone service provider recorded the highest call attempts using their 3G network above 8,000 ft. Two service providers could only provide connection below 8,000 ft.
The Telco service provider expert cautioned the Team that the tests would be difficult to conclude and use as scientific/theoretical assumptions for the case of MH370, as the measurement results were only valid for that specific time, flight path, speed, altitude, devices used, and environment during the tests.