NEW YORK — A citizens group has taken aim at one of the few remaining outposts of industry and commerce on Manhattan's reborn Hudson River waterfront: a noisy helipad that shares a narrow esplanade with joggers and cyclists.

The group, Friends of Hudson River Park, claims in a lawsuit that the state law that began turning a dreary stretch of West Side waterfront into parkland several years ago required the 30th Street Heliport to leave its riverside perch no later than 2001.

Instead, the public trust that oversees the park has let the helipad stay on, even as the park grew around it.

Today, the helipad launches sightseeing flights and VIP air shuttles from an asphalt patch little wider than a convenience store parking lot, while, mere feet away, children on skateboards cover their ears and runners hustle through jets of exhaust fumes.

Matthew Washington, a spokesman for Friends of Hudson River Park, called the landing choppers "frightening and intimidating." The group's lawyer, Daniel Alterman, said the noise from the operation is 10 times the Environmental Protection Agency standard for parkland.

The group's lawsuit, filed in state court in Manhattan, seeks the immediate closure of the heliport.

News of the suit was greeted with alarm by Liberty Helicopter Tours, which operates at the site.

"This is a crisis point for the heliport. Its very future is now in jeopardy," said the company's attorney, the former deputy mayor Randy Mastro.

"There's a compelling need for a heliport on the West Side of Manhattan," he added, and called on elected officials to take quick action to either save or relocate the facility.

City and state officials have been talking about relocating the helipad for years, or possibly curtailing its use by banning sightseeing flights. Mayor Michael Bloomberg has said a West Side helipad of some type is important to the city's corporate sector.

In recent years, miles of decrepit piers and wharfs along the Hudson have been transformed into a delightful string of esplanades, playgrounds, picnic areas and lawns.