The sons of a passenger on the doomed Malaysia Airlines MH370 flight that disappeared earlier this year have sued the company and the government.

Two boys who were sons of Jee Jing Hang, a businessman who perished aboard the vanished flight, filed suit against the Malaysian government, civil aviation authorities, the air force, and the immigration department for negligence that caused the tragedy.

Their argument centers on the claim that when their father paid for a ticket, he entered into a contract with Malaysia Airlines for safe travels to Beijing, a contract that was breached when the plane failed to arrive at its destination.

The sons will seek to collect “aggravated and exemplary damages” for loss of support and mental anguish, reported China’s Xinhau news agency.

The flight vanished March 8 and was never found. The plane was carrying 239 people on a flight from Kuala Lumpur to Beijing.

The tragedy is already one of the greatest mysteries in aviation history. Authorities still have been unable to locate where the plane crashed, assumed somewhere in the Indian Ocean. The last message air traffic control received was when the plane was flying over the South China Sea a mere hour after takeoff. Military radar placed it over Andaman Sea about an hour later 200 miles northwest of Malaysia. This finding indicated that the plane did not crash right away, but was flying for an unknown period of time but for some reason did not communicate with air traffic control.

Authorities from both Malaysia as well as China, the United States, and many other nations desperately searched for the plane’s black box, but came up empty. Their search led them to the Indian Ocean west of Australia, which would have been far off the plane’s scheduled course.