The Civil Aviation Administration of China said the threats appeared to be false.

WSJ: Chinese Airlines Receive Flight Threats

The head of the Civil Aviation Administration, Mohammed Sherif, told The Associated Press at the scene of the crash that the pilot had just renewed his license in January.

NPR: Fiery Balloon Accident Kills 19 Tourists In Egypt

However, oddly enough, the Federal Aviation Administration, its British counterpart, the Civil Aviation Authority, and Europe's Joint Aviation Authorities do not require the use of these filters on commercial airlines.

CNN: Commentary: Flu and your health on a plane

No one was seriously injured in any of the events, and the National Transportation Safety Board, an independent federal agency charged with investigating civil aviation accidents in the US, and the Federal Aviation Administration, the national aviation authority of the US, have ordered investigations into the incidents.

BBC: Is the Boeing Dreamliner safe?

The Civil Aviation Ministry, like much of the government administration, has seen political disputes since President Mohammed Morsi came to power in June as Egypt's first freely elected leader.

NPR: Fiery Balloon Accident Kills 19 Tourists In Egypt