In 2000 a New York City study of helicopter noise and its effect on residents reported that helicopters were not being forced to comply with noise and pollution regulations.  The council said that there is no provision in the Clean Air Act regulating pollution from aircraft.

"There is an urgent need for noise relief," said Cunningham, author of the report. "Helicopter noise is annoying because of blade slap and low-frequency noise that results in building vibration."

She said residents also should be concerned about potentially harmful toxins released into the air by helicopters.  City Councilwoman Christine Quinn (D-Chelsea) said she had received all sorts of complaints from constituents about helicopter noise.

Helicopter noise is inherently more complex to model than jet aircraft noise.

Helicopter noise tends to have a pulsating quality caused by the blade passing frequencies of the rotors. Under certain conditions, this can become pronounced and is termed ‘blade slap’. The forward motion of a helicopter in normal flight results in variations of blade speed through the air during each rotation formed by a combination of the forward speed of the aircraft and the rotation of the blade.

A SHARP rise in the number of helicopter sightseeing trips above the Capital has sparked a growing number of noise complaints - but authorities say they are powerless to silence the fliers.

Since the start of the year, six complaints about helicopter noise have been made to council chiefs as more and more people buy helicopter trips as presents for birthdays, graduations and weddings - causing headaches for people on the ground below.