content: The transponder stopped transmitting, pasting a reddit comment: 'All according to FlightRadar24.... It was a Boeing 737-8KV, registration UR-PSR. It was delivered new to Ukrainian Air 3.6 years ago. FYI this was the older generation of 737, obviously not the MAX, as those are still grounded.  The plane took off from Tehran with callsign Alpha-Uniform-India-7-5-2 at 6:12am local time, almost an hour after the 5:15am scheduled departure.  The FR24 playback of the transponder shows the plane climbing up to about 8,000ft and then.... nothing: https://fr24.com/data/flights/ps752#23732569  Doesn’t look good. I find it interesting that the transponder just stopped transmitting altitude and speed data. Usually in plane crashes you can see the altitude and speed graph all the way to the ground. It either must have been very quick, or shut off intentionally. Now is not the time to stir the conspiracy pot though. Hopefully there are survivors. EDIT: to all of the people saying that FlightAware still shows it in the air... FR24 uses much more reliable ADS-B data.'