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Charles's avatar

To add to what I wrote earlier, there have been reports of passengers having made cellular phone calls to their families from aircraft which are about to crash. Well, these most probably were made via micro-base stations in the aircraft carried over the aircraft's satellite link to the ground station.

According to Wikipedia, "the datalink for Malaysia Airline's avionics communications at the time of the incident was supplied by SITA, which contracted with Inmarsat to provide a satellite communication link using Inmarsat's Classic Aero service.

Satellite communications between MH370 and the ground stations was made from the satellite data unit (SDU) on MH370 to Inmarsat's satellite above the Indian Ocean, which relayed communication down to Inmarsat's satellite ground station in Perth, Australia.

https://en.wikipedia.org/wiki/SITA_(company)

SITA (Société Internationale de Télécommunications Aéronautiques) is a multinational information technology company providing IT and telecommunication services to the air transport industry. The company provides its services to around 400 members and 2,500 customers worldwide, which it claims is about 90% of the world's airline business. Around the world, nearly every passenger flight relies on SITA technology.

https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370_satellite_communications

So if the SDU on MH370 was turned off or disabled, cellular phone calls from MH370 to someone on the ground would have been impossible.

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Charles's avatar

I have a doubt about this:

"The phone call Fariq was reported to have tried to make over Penang even adds more weight to the MH370 disappearance being a deliberate act."

As far as I understand, it is not possible to make cellular telephone calls from high up in an aircraft, unless there are cellular micro-base stations or what are called femtocells installed on the aircraft itself, which are in-turn connected to ground stations through the plane's radio-communication systems.

Likewise if you can make a cellular phone call from the top floor of a very tall building, from the lowest level of an underground car part or from a metro train running underground or from an underground metro train station, this would only be possible if there are micro-base stations installed within these areas which are connected to your cellular operator's network usually via Ethernet LAN cable or fibre.

Cellular base stations ideally have their antennas mounted at a height of about four storeys above the ground. There usually are three antennas per base station, with each one covering a 120 degrees arc, with the set of three providing 360 degrees coverage of the ground around the base station. The beams of these antennas usually point horizontally outwards and slightly downward to cover a roughly circular cell area with a radius of from 3 to around 5 kilometres around the base station. The lower the frequencies used by the base station and the by the generation of cellular communications - i.e. 1G, 2G, 3G, 4G and 5G, the longer the range of the base station's coverage.

Each of these base stations usually are connected to the core of your cellular service provider's network via cable, usually fiber these days, or where a physical connection is not possible, via point-to-point, high-capacity microwave radio links.

To enable continuous coverage over a wide area beyond the range of each base station, the cellular network operator installs sets of seven base stations arranged in a honeycomb topology, with handoff or the cellular phone (such as in a moving vehicle) between base stations as it crosses between the respective coverage areas of adjacent base stations.

With the range of frequencies assigned for the operator's use by the communications regulator being sub-divided into seven sets different of frequencies used by each base station to avoid interference between of frequencies between adjacent base stations, and cellular base stations using the same sub-set of frequencies are placed far enough apart to avoid interference.

To come to the main point I wish to make, way back in the late 1990s, I was on the top floor of what was the 22-storey Sime Darby (now Wisma FGV) building in Kuala Lumpur and my 2G GSM (900MHz) cellular signal lost its connection to my cellular service provider's base station signal.

Later I experienced a similar loss of cellular signal when I was in one of the top floors of the 50-storey Maybank Tower (243.5 metres tall) plus the height of the hill upon which it stands.

So if my cellular phone lost its connection to the base station at such building heights, what more from a plane at heights of 35,000 feet (10,668) and way out above the sea, hundreds or even thousands of kilometres from terrestrial base stations.

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