Aerospace Forecast Report finds sustained increase in overall air travel and use of Unmanned Aircraft Systems. FAA estimates small, hobbyist UAS purchases may grow from 1.9 million in 2016 to 4.3 million by 2020, and sales of UAS for commercial purposes are expected to grow from 600,000 in 2016 to 2.7 million by 2020. Forecast calls for Revenue Passenger Miles by mainline and regional air carriers to grow 2.6% a year from 2016–2036, with international RPMs projected to increase 3.5% a year.