My Dad started flying for Northeast in 1966, the year the Yellowbird campaign was introduced. Before Planeviz changed focus I had a long post here covering the evolution of Northeast and the Yellowbirds until the Delta acquisition.
Since retiring the post I came across this video from the Starboard76 YouTube channel that has everything from the DC-6 to the Yellowbird CV-880, CV-990, 727, and DC-9. It’s the best collection of Northeast Yellowbirds I have seen. The CV-880 below is being pushed back from NEA’s Miami concourse. Northeast leased the 880s and sole 990 from TWA and American respectively.
With the Yellowbird theme and fleet makeover, Northeast went from a stodgy prop airline to 1960s jet-set sexy. Unfortunately, competing with Eastern and National on the lucrative Florida routes and having to still fly unprofitable New England local routes wasn’t financially viable and Northeast was merged into Delta in 1972.