Okay, I did a Google search for "broken arrow", and after three (!)
screens mostly about a town in Oklahoma and the movie referenced
above, I came to this:

http://www.atomicmuseum.com/tour/cw4.cfm

Broken Arrow

On January 17, 1966, an SAC B-52 had a mid-air collision with a KC-135
tanker while refueling over Palomares, Spain. The B-52 was carrying
four thermonuclear B28 bombs. The bomber had begun the mission at
Seymour Johnson AFB, North Carolina. The KC-135 had come from the
Moron Air Base, Spain. All four KC-135 crew members were killed, while
four of the seven B-52 crew parachuted to safety.

President Lyndon Johnson, the Department of Defense, the Atomic Energy
Commission, and the Spanish Government received news of the nuclear
accident. Nuclear safety teams were dispatched immediately. Within
hours, the 16th Air Force had located the three B28 bombs that landed
on the shore. However, the fourth bomb was missing; it was not found
for 80 days. High explosives in two bombs had detonated on impact.
Plutonium dust had spread over several hundred acres. One reassuring
fact emerged from this incident: inherent safety features designed and
built by Atomic Energy Commission contractors ensured that no nuclear
explosion occurred.

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So I reckon the term was fairly specialized, at least at as far as
Google is concerned.

all the best -- Dan Ford
email: (put Cubdriver in subject line)

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