for Los Angeles. Fifty-one passengers and the five hijackers boarded the 767 through Terminal C's Gate 19. The plane pushed back at 07:58 and took off at 08:14 from runway 9,[2][11] about the same time Flight 11 was hijacked. By 08:33, the aircraft reached cruising altitude of 31,000 feet, which is the point when cabin service would normally begin.[2] At 08:37, air traffic controllers asked the pilots of Flight 175 whether they could see American Airlines Flight 11. The crew responded that Flight 11 was at 29,000 feet, and controllers ordered Flight 175 to turn and avoid the aircraft.[12] The pilots declared that they had heard a suspicious transmission from Flight 11 upon takeoff. "Sounds like someone keyed the mic and said everyone stay in your seats," theflight crew reported. This was the last transmission from Flight 175.[13]

It is estimated that Flight 175 was hijacked between 08:42 and 08:46, while Flight 11 was just minutes away from hitting the North Tower.[2] According to Flight 175: As the World Watched, it's believed that "muscle hijackers" Fayez Banihammad and Mohand al-Shehri forcibly entered the cockpit and killed the pilots while Hamza al-Ghamdi and Ahmed al-Ghamdi started moving passengers and crew to the back of the aircraft. The first operational evidence that something was abnormal on Flight 175 came at 08:47, when the plane's transponder signal changed twice within the span of one minute, and the aircraft began deviating from its assigned course.[11][14] However, the air traffic controller in charge of the flight did not notice until minutes