View of Trinidad, DC from a chopper

From a Reader:

Titan, what’s with all the helicopter noise lately?  We sometimes hear a chopper for the Marine One or police flights, but it was really frequent the past week.  On the weekend it was nearly constant for part of the day.  Is MPD or Marine One doing training or are there just more VIPs flying over lately?

Yes, we do occasionally get a police helicopter or Marine One flying overhead, but the answer (in this case) appears to be none of the above.   The National Nuclear Security Administration, charged with securing the nation against nuclear threats (as the name implies), has been conducting flyovers the past week or so to measure the baseline level of radiation in the District.

The operation uses a low-flying helicopter to fly back and forth to measure the area’s radiation level, much like a lawnmower mows back and forth to cut a yard’s grass.   Once this baseline is complete, officials will be able to re-scan a section of DC in the event of a suspected nuclear threat to determine if there is a significant change from current readings.

The good news, for those annoyed with the noise: Today (January 11) is the last day for scheduled radiation scanning.

CNN has a video piece on the scanning, and here’s a bit more from the NNSA:

The National Nuclear Security Administration (NNSA) will be flying a helicopter over portions of Washington, D.C., between Dec. 27, 2012, and Jan. 11, 2013. The purpose of these flights is to measure naturally occurring radiation in the Washington, D.C., area.

The radiation assessment will cover approximately 70 square miles and NNSA will complete the assessment using a helicopter equipped with remote gamma radiation sensing technology. The helicopter will fly in a grid pattern over the areas, 150 feet or higher above the ground surface, at a speed of approximately 80 miles per hour. Flyovers will occur only during daylight hours and it is estimated to take about two weeks to complete the assessment.

The measurement of naturally occurring radiation to establish baseline levels is a normal part of security and emergency preparedness. NNSA is making the public aware of the upcoming flights so that citizens who see the low-flying aircraft are not alarmed.

The NNSA’s Remote Sensing Laboratory (RSL) out of Joint Base Andrews will be performing the assessment for local law enforcement of Washington, D.C.