LAS VEGAS (KLAS) — Low-altitude helicopter flights over the Las Vegas Strip are usually forbidden, but on Friday and Sunday, it’s part of this year’s prep work for New Year’s Eve.

The public should not be alarmed by a helicopter flying a grid pattern as low as 150 feet off the ground, according to a National Nuclear Security Administration (NNSA) news release.

The NNSA helicopter flies over the Las Vegas Strip on a previous mission. (Photo: National Nuclear Security Administration)

NNSA will be in the air to conduct radiation surveys to measure background radiation levels. That data will help security operations detect any spikes as New Year’s Eve celebrations take place on the Strip. The surveys are conducted each year leading up to the Las Vegas event.

A twin-engine Bell 412 helicopter will conduct the flyovers during daylight hours on Friday, Dec. 29, and Sunday, Dec. 31. The flights will take about two hours to complete per area, according to the NNSA’s news release. The helicopter will be flying at about 80 mph.

“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,” according to NNSA, which is part of the U.S. Department of Energy.