After an air and sea search that covered an area five times the size of O'ahu, the U.S. Coast Guard yesterday said it will stop actively looking for the missing pilot in the helicopter crash that killed four crewmen on Thursday.

"It's with a heavy heart, that I announce my intention, pending further developments, to suspend the search for the missing crew member of Coast Guard 6505," said Coast Guard Rear Adm. Manson Brown. "We're continuing to search in earnest, but anticipate stopping our active search at the onset of darkness."

The body of Cmdr. Thomas Nelson, 42, of Staten Island, N.Y., has not been found. He left behind two daughters and a wife. He recently was put up for promotion to the rank of captain, Brown said.

The HH-65 Dolphin helicopter crashed about five miles south of Honolulu International Airport Thursday night during a routine rescue exercise with a Honolulu Station lifeboat. Coast Guard officials received a distress signal from the 47-foot lifeboat, whose crew watched the helicopter crash at 8:15 p.m.

Nelson came to Hawai'i in July 2007. He was posted at Air Station Barbers Point as executive officer, the second in command at the air station. Before coming to Hawai'i he served as the deputy chief, Office of Security and Defense Operations at Coast Guard headquarters in Washington, D.C., from July 2004 to June 2007. Previously, he had been stationed at Air Station Brooklyn, N.Y.; Air Station Port Angeles, Wash.; and Air Station New Orleans.

"Cmdr. Nelson's Coast Guard service of two decades demonstrates his unwavering commitment to the Coast Guard and to the protection of mariners across the country," Brown said.

The Coast Guard identified the other three crew members killed as co-pilot Lt. Cmdr. Andrew Wischmeier, 44, of Fort Lauderdale, Fla.; rescue swimmer Petty Officer 1st Class David Skimin, 38, of San Bernardino, Calif.; and flight mechanic Petty Officer 2nd Class Joshua Nichols, 27, of Gloucester, Va.

Investigators will begin to sift through the recovered debris from the crash, which includes the helicopter's fuselage and its so-called black box, which contains instruments that record details of the flight, Brown said. The debris is stored in a hangar at Hickam Air Force Base, where the Coast Guard's investigative team from Washington, D.C., will try to determine the cause of the crash.

Yesterday's search did not turn up any additional debris, Brown said. The Coast Guard brought in three air crews from California and Alaska to augment the staff at the 300-member Air Station Barbers Point, Brown said.

"We are such a small group, it's more like a family and every member is affected by an accident," said Coast Guard spokesman Lt. John Titchen. "It's especially tough because we're performing the job we're trained to do, but we're searching for one of our own. We're all struggling."

The Navy, Air Force, Hawai'i Air National Guard, Coast Guard Auxiliary, the state fire department at Honolulu International Airport, the Honolulu Fire Department, the Honolulu Police Department and the state Department of Land and Natural Resources all helped with the three-day search,Titchen said.

During the search, 91 patrols were made, covering more than 3,000 square miles. Yesterday only the HFD helped in the air and sea search.