KALAELOA — An investigation into a 2008 Coast Guard helicopter crash that killed all four crew members found that the incident began when a cable from the aircraft snagged on a boat during night training.

The cable snapped, and the violent jerking motion caused the rotors to hit the helicopter's hoist boom used to reel in the quarter-inch steel line.

The air crew continued to fly the damaged HH-65 Dolphin, rather than try to ditch at sea south of O'ahu.

But just over three minutes after the initial accident, and after traveling nearly 2 1/2 miles, the aircraft experienced a "catastrophic loss of airworthiness" and crashed into the sea from an altitude of more than 450 feet, the investigation released yesterday reveals.

Killed in the Sept. 4, 2008, accident were Capt. Thomas Nelson, 42; Lt. Cmdr. Andrew Wischmeier, 44; rescue swimmer Petty Officer 1st Class David Skimin, 38; and flight mechanic Petty Officer 1st Class Joshua Nichols, 27.

As a result of the crash, the Coast Guard has decided to conduct a safety hazard analysis of its helicopter hoist assemblies. The realism and frequency of flight training leading to ditching at sea also will be increased, among other changes.

Susan Buck-Wischmeier, whose husband was the pilot in command, yesterday said it's been an incredibly difficult year.

The Käne'ohe resident attended a news conference yesterday at Coast Guard Air Station Barbers Point, where the investigation findings were released.

She and a relative also placed lei on a memorial at the Kalaeloa air station to those killed in the 2008 crash.

Asked where she finds her strength, Buck-Wischmeier said, "That's a really good question. Lot of days I'm not sure I have any. But friends and family and the Coast Guard really have been tremendous at supporting us. It's the 'ohana."

NO MISCONDUCT

She said if her husband were still alive, he'd say he fought as hard as he could to get back home.

"They gave it all they could," Buck-Wischmeier said. "They prevented the helicopter from going in (after the cable broke), and they fought. I mean, they wanted to get home. They saw land, and I know my husband, he would have thought, 'If anybody can get this helicopter home, I can.' "

Wischmeier was an instructor pilot, and the other crew members also were experienced.

"You couldn't ask for a more experienced crew," said Cmdr. Carl Riedlin, the executive officer for Air Station Barbers Point.

An "administrative" investigation signed by Adm. Thad Allen, commandant of the Coast Guard, found that there was no misconduct associated with the crew, but that the "non-performance of required emergency procedures contributed to the severity" of the accident.

There was no "clear verbal annunciation" of emergency procedures after the hoist cable broke, and although the crew knew there were multiple emergencies, the pilots became "task-saturated" with flying the still-controllable aircraft.

An ancillary safety investigation by the Coast Guard said it would have been "reasonable to have expected the aircrew in this case to diagnose the (damaged helicopter's) vibrations as severe enough to warrant ditching."

The helicopter, with the tail number 6505, was on its fifth hoist while conducting night rescue basket training with a 47-foot motor life boat.

While beginning to recover the basket, the hoist cable went slack due to the motion of the helicopter and boat in the waves, and the cable looped and snagged on a pipe used to pump water out of the boat's hull.

When the boat dropped into the trough of a wave, the cable went taught and broke, violently rolling the helicopter to the right and then the left, at which point the rotors hit the hoist boom, mounted externally above the starboard side door.

The chopper climbed to an altitude of 558 feet at about 50 mph as "Mayday" calls went out and an attempt was made to reach O'ahu's southern shore.

Damage to the rotor system wracked the 44-foot helicopter with severe vibration. A Coast Guard official said the loss of control might have made it impossible to hover to ditch at sea, although the two pilots' thoughts are not known.

The helicopter went down at about 8:15 p.m. about five miles southwest of Honolulu International Airport in waters about 1,300 feet deep.

The safety investigation said the aircraft's crash most likely was caused by a sudden loss of rotor speed from damage to the rotor system and "out-of-balance condition."