A frequent flyer around the Bethesda campus is the EC AS-65, a medical evacuation helicopter.

Second, as NNMC is integrated with Walter Reed Army Medical Center, more service personnel, veterans and their dependents will require “medevac” (the military term for air ambulance service) to and from Bethesda.

The numbers are increasing daily: 800 rotorcraft— that is, helicopters—transport 1,000 patients a day in the U.S.; that’s a lift-off every 90 seconds. Suburban Hospital counts 400-500 flights per year; NNMC claims 120-140 flights, with the Base Closure and Realignment Commission (BRAC) changes at Navy adding more.

Meanwhile, “the noise and safety impacts of helicopter flights are relevant not only to NIH neighbors,” says Coleman, “but also to the NIH mission. The [Bethesda] campus itself is supposed to be a natural as opposed to industrial setting and include ‘contemplative areas’ where staff can go outside and think about their biomedical research.”

That idea is embedded in the word campus (meaning “field” in Latin). The 306-acre Bethesda campus boasts a creek, lawns, woodlands and preservation areas with their own flight traffic: the 50 species of birds seen nesting or feeding hereabouts.

“There is a noise and potential safety issue here,” says Coleman, “since NIH also has patients and tall buildings.”

Moreover, he notes that as chopper traffic has increased, community members have asked him to research information on the regulatory, legal and agency framework protecting “both public and operator interests.”

Although NIH has no helipad, Coleman heard neighbors’ concerns and, assisted by Sharon Robinson, has just released a report to the Community Liaison Council titled “Regulatory Survey of Urban Helicopter Operations and Associated Emergency Medical Transport Services.”

According to the report, the most recent FAA advisory circular recommends “avoidance of flights over noise-sensitive areas”; if that’s not possible, then pilots should “make every effort to fly at least 2,000 feet above the surface.” Minimum safe altitude recommended is 1,000 feet.

Bethesda itself is deemed a “noise-sensitive area” by the Metropolitan Washington Council of Governments, given its population density and the number of hospitals.

Above, l: Three views of the UH-IV—also known as the “Huey”— a multipurpose military helicopter used to transport patients Above, r: The UH-IV/Huey has a radar altimeter, distance-measuring equipment, instrument landing system and a rescue hoist.

“We live very close to Suburban at the south end of campus,” says OD employee Dr. Penny Burgoon, “and it feels like they’re landing on top of the house.”

And what of safety? Coleman notes that air ambulance pilots tend to be the best, but 1 of every 10,000 flights ends in an accident, especially when densely developed urban areas and associated obstacles are involved. This, he says, is why recommended flight paths are generally over streams, highways, parks and other open areas.

Yet the regulatory matrix is intricate, with multiple overlapping federal, state and local agencies as well as private industry. So if folks have questions or concerns, “it’s usually more effective for communities impacted by helicopter operations to keep it simple at first and start by communicating their concerns directly to the facility operators.” That means the security manager at Suburban Hospital and the Public Affairs Office at Navy Med.

How loud is too loud? To put the numbers in perspective, sound is measured in decibels (dBA) and the scale is not linear, but logarithmic. In other words, the threshold of human hearing is 3 dBA, and every 10 dBA increase beyond that sounds 50 percent louder. Some examples:

• Montgomery County’s nighttime noise limit is 55 dBA; 65 during the day;
• A normal conversation from 3 feet away is 60 dBA;
• A helicopter from 1,000 feet away is 70-90 dBA.

According to the National Institute on Deafness and Other Communication Disorders, long -term, unprotected exposure to sounds at or above 85 decibels can damage your ears.

This doesn’t mean that you can’t cut your grass with a power mower (90 dBA) in Montgomery County.

“In reality,” says Coleman, “the enforcement is selective and discretionary. It’s all a balance and there is an element of societal benefit that goes into enforcement.”

Meanwhile, since 1981, the Fly Neighborly Program, one of the industry’s self-regulating efforts to avoid further government regulation, has been accepted by civil, military and government operators.

What makes helicopters so loud, of course, is the noise of the engines and rotors. The only flying machine designed to hover, the helicopter typically has one or two turbine engines with 1,000 to 2,000 horsepower each and serves multiple uses, including rescue and transport.

Coleman cites 14 types of helicopters that fly into and out of Bethesda. Versatile and durable, they come in small (Bell 206L, Bell 407, EC AS-350); medium (BK-117, A-109, EC-135, EC-145, Bell 430); large (S-76, AS-365, Bell 2120); and military (VH-3D, the “Marine One” ’copter used to transport the President; UH-IV, the “Huey”; and UH-60—the “Blackhawk”).

No matter the size or sound, the rotorcraft seen locally are usually moving patients, which is a mission few can complain about.