Kenyan Shabab Operative Planned 9/11-Style Attack, U.S. Says - The New York Times

... Mr. Abdullah began the process of enrolling in a flight school in the Philippines in 2016, received training and ultimately completed the tests necessary to obtain his pilot's license, according to the indictment. He also researched methods of hijacking a commercial airliner, such as how to breach a cockpit door from the outside, the indictment charged...

https://www.nytimes.com/2020/12/16/nyregion/cholo-abdi-abdullah-shabab-indictment.html