WASHINGTON –The U.S. Department of Energy’s National Nuclear Security Administration (NNSA) will conduct low-altitude helicopter flights over the Boston Marathon route Wednesday, April 13, through Monday, April 18 in preparation for the race and the events related to it.

The flights were originally to start on Thursday, April 14, but the weather forecast prompted a change.

NNSA’s Nuclear Emergency Support Team (NEST) aircraft will measure expected background radiation as part of standard preparations to protect public health and safety on the day of an event.

The public may see NNSA’s twin-engine Bell 412 helicopter, which is equipped with radiation-sensing technology. The helicopter will fly in a grid pattern over the areas at 150 feet (or higher) above the ground at a speed of approximately 80 mph. Flyovers will occur only during daylight hours and are estimated to take approximately two hours to complete per area.

These surveys are a normal part of security and emergency preparedness activities. NNSA is making the public aware of the upcoming flights so citizens who see the low-flying aircraft are not alarmed.

For more information and video footage of NNSA’s Aerial Measuring System, click here.

NEST is part of NNSA’s Counterterrorism and Counterproliferation Program and is an element of the Nation’s nuclear or radiological emergency response capability.