Thread by @AFLCMCHO

#OTD 1972 - Happy 50th Anniversary of the 1st Flight of the @BoeingDefense EC-137D, prototype for the E-3 Sentry Airborne Warning & Control System (AWACS). A thread. 1/6 @AFLCMCofficial @Team_Tinker @Hanscom_AFB @NATOAWACS

2/6 Airborne Early Warning Radar used since #WWII, needed to detect aircraft flying below ground radars. But trouble tracking multiple targets in 3D, esp over land. Radar reflections off surface aka "ground clutter" biggest issue. 1960s state of art was Lockheed EC-121D (pic)

3/6 Advances in pulse Doppler radar & compact computing made "look-down" radar feasible. Tac Air Cmd & Air Def Cmd issued joint Specific Op Req 206 in 1963 for Airborne Warning & Control Sys. Aero Sys Div @WrightPattAFB began Overland Radar Tech Program, incl. @AFResearchLab

4/6 Program trans. to Electronic Sys Div
@Hanscom_AFB in 1967. In 1970 Boeing won AWACS prime contract, used 707-320D airframe, managed fly-off between Hughes & Westinghouse radars, designed pancake rotodome on 2 struts, held initial flight tests.

5/6 Boeing converted 2 707s to EC-137Ds for radar flight tests. Tail nos. 71-1407/8. 1407 rolled out of Boeing Renton WA plant 1 Feb 72. Made 1st airworthiness flight test (no radar equip., used ballast) there on 9 Feb 72. 7 flights thru 17 Feb to test flying/stability qualities.

6/6 Radar flyoff lasted thru Oct. 72, Westinghouse won. AF dubbed AWACS the E-3 Sentry. 68 built on 707 airframes, operational in 1977, used by @usairforce, @NATOAWACS, etc. Both EC-137Ds converted to standard E-3 config & still serve
@Team_Tinker 552nd Air Control Wing

Postscript: yesterday
@AFLCMCofficial issued RFI for E-3 AWACS replacement. Calls for similar start as original AWACS, w/2 prototypes.
sam.gov/opp/b47eca2a3f…

(We opted to retweet this thread minus the typos for posterity. Thanks to our readers for catching that!)