GoKawiil1991 AT&T building battery failure disabled NY-area FAA air traffic systems
On September 17, 1991, a routine Con Edison-requested power transfer led to a rectifier trip at AT&T's 33 Thomas Street facility in Manhattan, which went unnoticed as backup batteries silently kept DC power flowing to FAA telecom lines. Hours later the batteries drained, cutting radar feeds, radios, and flight-handoff links for New York's radar center and the Kennedy, LaGuardia, and Newark towers simultaneously, forcing controllers onto manual backups and resulting in 1,174 flights delayed or canceled.