from theguardian.com: A U-2 spy plane passing overhead crashed the air traffic control for Los
Angeles and a wide surrounding area, leading to hundreds of services
being grounded, authorities have revealed. Controllers had to resort to
emergency back-up procedures, calling each other manually to keep track
of planes already flying in the busy airspace while the system was
rebooted and fixed.
The Cold War-era U2 plane flies at high altitude, around 60,000 feet
(18,000 metres) under "visual flight rules". The Federal Aviation
Administration said the computer perceived the plane as a low-altitude
operation and began frantically trying to reroute it down to 10,000 feet
while keeping other planes out of its way.