Conspiracy theories will fly even if we don't know if MA Flight 370 is.
Chinese news forums say that some of the passengers' mobile phones were still ringing after the plane lost contact.
According to China.org.cn reporter Zhang Rui, 19 families signed a joint statement requesting Malaysian Airlines to disclose the truth to them, and explain why they could get through to their family members' cell phones but they could not hear anything and the calls hung up. They submitted the telephone numbers to the airline, which failed to response their questions with active measures. In response, angry family members threw water bottles at the spokesman, and vowed to protest in front of the Malaysian Embassy to China if Malaysia Airlines didn't disclose the truth of the incident.
The Missiles That Brought Down TWA Flight 800
A coverup by the FBI and the NTSB (National Transportation Safety Board) was blatant and extensive, involving intimidation of witnesses and investigators, tampering with evidence, false testimony before Congress, censoring reports, and numerous violations of normal protocols. Some of the government's own official investigators concluded that the explosion(s) occurred outside the airplane. They were not permitted to write analyses in their reports, as in every other investigation. Their reports were censored. They were forbidden to testify. Some 200 eyewitnesses — people on the ground and in other planes, at least many of whom described seeing one or more missiles rising from the ground to the airplane — were censored as well. Not a single witness was permitted to testify at the public hearing.
Investigators thought and still think a missile or missiles brought down the plane. Eye-witnesses thought and still think the same. Explosives residue in the plane wreckage and other physical evidence in the wreckage suggests missile(s). Data from several different radars at the time of the disaster show pieces of the plane being blown off at speeds that could only have been generated by high explosives, not by a fuel tank exploding. Radar data also show the plane falling, not rising. (The CIA claimed, without offering any evidence, that the plane rose into the sky as it was exploding, thus accounting for witnesses' reports of seeing objects rising.) The damage to the seats and passengers in the plane was random, not greater closer to a fuel tank.
Iran Air Flight 655
July 3, 1988, a U.S. Navy ship called the Vincennes was exchanging fire with small Iranian ships in the Persian Gulf. The U.S. Navy kept ships there, and still does, to protect oil trade routes. As the American and Iranian ships skirmished, Iran Air Flight 655 took off from nearby Bandar Abbas International Airport, bound for Dubai. The airport was used by both civilian and military aircraft. The Vincennes mistook the lumbering Airbus A300 civilian airliner for a much smaller and faster F-14 fighter jet, perhaps in the heat of battle or perhaps because the flight allegedly did not identify itself. It fired two surface-to-air missiles, killing all 290 passengers and crew members on board.