During these uncertain times, it’s not uncommon to see encouraging messages scrawled on the sidewalks in chalk. But apparently, we should also be spending some time looking on Flightradar24, as pilots are sending special messages to people around the world by using their flight pattern to spell out letters and symbols.

A message in the sky over Austria, spelled out by an unknown pilot of a private DA40 aircraft, read “stay home” to promote social distancing. This particular flight departed earlier this month from an airport in Wiener Neustadt, 45 miles south of Vienna, and returned soon after spelling out the message.

As recently as Friday, March 27, another pilot expressed support for healthcare workers by drawing a thumbs up next to a medical cross in the sky over Hungary. This pilot, at the helm of a privately owned Magnus Fusion 212, might not be able to assist with the coronavirus, but is still showing support.

Although these messages can’t be seen in the sky, they are picked up by Flightradar24, a site that tracks the movements of aircraft around the world based on real-time air traffic information.