I’m not sure what the percentage is, but at least some aircraft will have to have ADS-B Out in 2020, per https://www.faa.gov/nextgen/programs/adsb/faq/#g2 https

I’m not sure what the percentage is, but at least some aircraft will have to have ADS-B Out in 2020, per https://www.faa.gov/nextgen/programs/adsb/faq/#g2 https://www.faa.gov/nextgen/programs/adsb/faq/#g2 I like the idea of requiring ADS-B Out on drones. For those aircraft with ADS-B In, it introduces the possibility of seeing drones sending ADS-B Out. And others with ADS-B receivers will be able to see and identify them. As an additional step, drones could be required to use ADS-B in for aircraft avoidance.