Why doesn’t a plane show up?

JetDex can only show aircraft that broadcast their position and that a receiver on the ground can hear. Common reasons a plane is missing:

• It doesn’t broadcast ADS-B. Many military aircraft, some older light aircraft, gliders and balloons don’t send their position, or only send it some of the time.
• No coverage. Over the open sea, in mountains and in remote areas there may be no volunteer receiver close enough. Coverage is excellent over most of Europe, North America and around big cities, thinner elsewhere.
• It is too far away. JetDex looks about 80 km around you. A plane you can see near the horizon may be further than that.
• It is very low. Aircraft close to the ground, just after take-off or before landing, can drop below what nearby receivers can hear.
• A short delay. Positions are a few seconds old. JetDex moves each plane forward to the current moment, but a plane turning sharply can briefly be in a slightly different place.

If you think coverage is missing where you live, you can help: a small ADS-B receiver and antenna can feed the open network at adsb.lol.