What's the difference between 1090 and 978?
You probably know by now that most airplanes will have to be equipped with ADS-B Out by January 1, 2020, in order to meet the FAA mandate. Beyond that basic issue, though, there are still a lot of questions to consider. One of the first is 1090 vs. 978. That is, should you install an ADS-B Out transponder that works on the 1090 MHz frequency (sometimes called 1090ES) or the 978 MHz frequency (sometimes called a 978 UAT)?