Sort of like the 727 midair with a small Cessna over downtown San Diego September 25, 1978. The 727 crew reported a Cessna in sight. Alas, they saw the wrong Cessna. Killed 144 people, including 7 on the ground (plus 9 injuries on the ground). Until the AAL DC-10 crash at KORD the following year it was the deadliest crash in U.S. history.
This accident gave new urgency for the ultimate development of TCAS.