A cybersecurity consultant told the FBI he hacked into computer systems aboard airliners up to 20 times and managed to control an aircraft engine during a flight, according to federal court documents. Chris Roberts was detained by the FBI in April following a United Airlines flight to Syracuse, New York, after officials saw Twitter posts he made discussing hacking into the plane he was traveling on. An FBI search warrant application filed in the U.S. District Court for the Northern District of New York describes the investigation of Roberts for possible computer crimes.

During FBI interviews in February and March, the document says, Roberts told investigators he hacked into in-flight entertainment systems aboard aircraft. He claimed to have done so 15 to 20 times from 2011 to 2014. He also said, according to the document, that once he had hacked into the systems and then overwrote code, enabling him to issue a “CLB,” or climb, command. “He stated that he thereby caused one of the airplane engines to climb resulting in a lateral or sideways movement of the plane during one of these flights,” the document says. Roberts said he knew of vulnerabilities aboard three types of Boeing aircraft and one Airbus model. He hacked into in-flight entertainment systems made by Thales and Panasonic, he told agents, according to the document. MORE