Department of Homeland Security and the National Nuclear Security Administration are flying the specially-equipped helicopter over three cities to map naturally-occurring radiation.
The government wants a baseline snapshot of safe, naturally-occurring radiation levels in the nation's urban areas, so in the event of a nuclear emergency it can compare that snapshot to whatever is going on at the time.
The twin-engine Bell helicopter has to fly low at about 300 feet to get the information it needs. Like a flying Geiger counter, the helicopter senses and measures naturally occurring radiation. Then in the event of a dirty bomb attack it would be able to differentiate between what's supposed to be there and what's not.
The ABC News program "Nightline" got a look inside a helicopter like it that would respond to a nuclear emergency in 2005. In that story, the on-board equipment was so sensitive it found a small amount of cesium in a vast stretch of the Nevada Desert.
"The radiation comes from the ground. All we do is detect it. We're just like an eyeball looking at something," mission manager Russell Malchow said.
The Department of Homeland Security's Nuclear Detection Office and the National Nuclear Security Administration have teamed up for this joint research project. The survey will cover about 69 square miles over Oakland, San Francisco and Pacifica.
The helicopter will be based out of Hayward and spend about two hours at a time flying a grid pattern. It flies so low and slow it attracts a lot of attention from people on the ground.
"Most of the time they're waving at us curious, plus it's a fairly noisy helicopter so it gets noticed," Chief pilot Manual Avaro said.
The specially equipped helicopter will be flying out of the Hayward Executive Airport for the remainder of the week, but exactly where and when is to be determined by the weather.