Full FAA Chronology at this link.
19400414: The first Air Corps detachment assigned to Alaska arrived at Fairbanks.
19610414: The first FAA-sponsored International Aviation Research and Development Symposium, convened at Atlantic City, covered subjects relating to advances in electronics and their application to air navigation and air traffic control systems. Attendees included officials of some 20 foreign governments and representatives of the electronics and aviation communities.
19750414: FAA eliminated the proposed requirement for altitude reporting transponders (Mode C) on all aircraft operating in Group II Terminal Control Areas (TCAs) 45 days before it was to go into effect (see June 8, 1973 and January 29, 1987).