In the American media environment drew attention to a clip, released the other day on the channel of the Ministry of Defense and dedicated to the 100th anniversary of the State Flight Test Center. American columnist Thomas Nedvik published an article, which talks about, that a Russian test pilot performed an impressive maneuver. It was piloting the latest Su-57 fighter in the cockpit without a "canopy".
American journalist called this version of the test flight "a flight in a convertible fighter".
Flight of the Su-57 without a "flashlight", probably, was associated with the assessment of emergency exit procedures. It is seen, that the cockpit windshield stays in place, and the back is completely removed, including frame.
The American military observer also draws attention to the flight suit of the Russian pilot.. He calls this flight suit "non-standard" – able to help the pilot withstand extremely cold temperatures when flying in "convertible mode".
American author notes, that this flight option resembles a departure, made in Britain by test pilot Keith (Whale) Hartley on a Panavia Tornado fighter in 1988 - during the development of the aircraft. Then the British development company reported, that the version of the tests was carried out specifically to practice the emergency exit procedure.
Ministry of Defense video, where a fragment of the discussed test flight of the Su-57 is captured: