A military officer takes notes during a search and rescue mission, onboard an aircraft belonging to the Vietnamese airforce
A military officer takes notes during a search and rescue mission, onboard an aircraft belonging to the Vietnamese airforce, off Vietnam's Tho Chu island March 10, 2014. The disappearance of Malaysia Airlines flight MH370 is an "unprecedented aviation mystery", a senior official said on Monday, with a massive air and sea search now in its third day failing to find any confirmed trace of the plane or 239 people aboard. REUTERS/Kham REUTERS/Kham

Video Source: YouTube/ CuteTV

Families of passengers aboard missing ill-fated Malaysian Airlines flight MH370 have been barraging telecom service providers to look into the mobile accounts of their loved ones. They claim to have been calling their phones and that these were ringing.

Families have been urging officials to track the signals to possibly locate the whereabouts of the airliner and all its passengers.

A man aired on a Beijing Television news bulletin was shown dialing the number of his older brother. The call connected and was able to ring for long but nobody picked it up.

Singapore's The Sunday Times reported likewise reported a Chinese family saying they were able to successfully contact the mobile phone of their kin during the flight. They said they called thrice the phone number but no one answered.

Malaysia Airlines Flight MH370 took off at 12.41am on Saturday at Kuala Lumpur and was scheduled to land in Beijing at 6.30 am. It went missing two hours after it took off, at 2.40am. Authorities and aviation experts presume it crashed off the Vietnamese coast after it lost contact with air traffic controllers off the eastern Malaysia coast.

Video Source: YouTube/ Jeff Wilson

There were 227 passengers on board Malaysian Airlines flight MH370, including two children, and 12 crew members. A total of 152 were Chinese nationals, 38 Malaysians, 12 people from Indonesia and six from Australia.

It remains a question as to why the pilots did not radio air traffic controllers regarding their predicament, if there was any at all.

Read: Malaysia Airlines Flight MH370: Wife of Kiwi Passenger Prays for Miracle, Air New Zealand Still Believes in Safety Features of Boeing 777s

"Something happened and the pilots did not tell anyone. Why? It's a good question," David Learmount, a pilot and also operations and safety editor of Flight Global magazine, said.

"It's extraordinary the pilots failed to call because they had plenty of time to. Unless there was a bomb on board but there has been no evidence of that."

While authorities and aviation experts are looking into probable terrorism threats as cause, they do not exclude the maintenance of the aircraft as another potential reason for the accident.