The plane's route had been closed by Ukrainian authorities below 32,000 feet, but the Malaysia plane was flying at approximately 33,000 feet when it crashed, according to Eurocontrol, an international air traffic management organization.
Fewer flights have crossed through Ukrainian airspace in the past month, but there has still been plenty of traffic, says Mikael Robertsson, co-founder of flight tracking website Flightradar24. There were two other planes within 10 minutes of the Malaysia 777 in its final moments, so it's not as if everyone had been avoiding the area.
FlightRadar24 provided the tracking information for the flight, which took off from Amsterdam and was headed for Kuala Lumpur. You can see it disappears about 25 miles before reaching the Russian border: