Suddenly the vibrations became the thunder of a low-flying helicopter.
Many animals were slaughtered by the country's military, which used low-flying helicopters to take pot shots at big game.
Sirens, low-flying helicopters and airplanes all made their customary appearances, but no one seemed to mind.
Their conversation was drowned by the drone of a low-flying helicopter.
Even the low-flying helicopters sometimes couldn't find a hole to go down through.
Part of the explanation, one official said, may be that fighters are simply firing at low-flying American helicopters.
A second later, my attention was drawn by a very low-flying black helicopter hovering over the tip of Manhattan.
As he was speaking, a volley of fire pursued a low-flying helicopter, which moved swiftly away.
The blades of a low-flying helicopter stir up the water beneath.
Over to my right, toward the hotel, a low-flying helicopter lit up the sky with its Nightsun.