Cockpit transcripts of the last moments before a Gulfstream jet crashed last year in Massachusetts, killing Inquirer co-owner Lewis Katz and six others, show the pilots suddenly realizing they had tried to take off with their tail elevators locked.

"Lock is on," the pilot said over and over, seven times in all, as the aircraft accelerated down the runway at Hanscom Field, outside Boston.

His next and last words were "I can't stop it," then "oh no no."

The Gulfstream G-IV crashed and burst into flames at 9:40 p.m. on May 31, as it sought to take off for Atlantic City after Katz and his friends had attended a Saturday fund-raiser at the home of historian Doris Kearns Goodwin. All who were aboard died.

The National Transportation Safety Board on Wednesday made public 800 pages of expert reports and documents on the crash but stopped short of providing an official cause. That will come in the fall in a final NTSB report on the crash of Katz's $30 million jet.

Still, the NTSB experts returned repeatedly to the theme of pilot error first suggested when the agency released its initial preliminary report shortly after the accident.

The new documents again say there was no evidence that the pilots performed preflight checks before the fatal takeoff.

Moreover, it disclosed for the first time that the experienced crew routinely took off without doing complete checks. Of a previous 176 takeoffs, the pilots only ran a complete flight check two times, a data recorder showed.

On the fatal flight, this meant the pilots tried to take off without realizing that they had failed to unlock the tail rudder, elevators, and wing ailerons, the NTSB documents suggest. A plane cannot go aloft if the elevators are locked.

The documents indicate the pilots compounded their mistake by deciding to go forward and attempt to take off even after instruments warned that the elevators were locked. They apparently attempted to unlock the elevators while the jet was rolling.

"It's abundantly clear to me that this was a pilot-error accident," Robert C. Hulse, a former Continental Airlines pilot and expert witness in aviation lawsuits, said Wednesday.

Hulse said the crash reflected a "fundamental failure in cockpit discipline" by veteran pilots.

"They should have aborted," Hulse added. "They could have stopped very easy."

The NTSB said its staff would not grant interviews.

Several of the agency's reports focused on the "gust lock" system, a fail-safe device on a plane's throttle - restricting speed if the rudders, elevators and ailerons are locked.

Upon landing, pilots routinely lock them down so when planes are parked on open fields such as Hanscom, aircraft are not blown around by the wind.

The lock - a simple bar that blocks movement of the throttle - was designed to bar a plane from going above taxiing speed if the elevators are locked. Yet the Gulfstream reached a peak speed of 190 m.p.h. before the pilots finally tried to stop by throwing the engines into reverse and hitting the brakes.

The experts' interest in the gust lock system reflects a search to understand why such a fail-safe system did not block the pilots from getting up to high speed.

They are trying to resolve a paradox: a review of the plane's debris found the gust lock was in an "off" position, yet the elevators were locked.

In a key report, NTSB investigator Timothy Sorensen cited an official study guide for Gulfstream G - IV, which advised pilots that if they inadvertently started the engines without disengaging the gust lock, they should shut down the engine to drop hydraulic pressure to zero, a time-consuming process.

However, Sorensen quoted an unnamed Gulfstream pilot as saying that some pilots had developed a work-around under which they could skip powering down the engines by only momentarily applying a power-shutoff handle. Sorensen stopped short of saying this is what the pilots did on the fatal flight.

In August, Gulfstream warned pilots of about 2,000 of its jets to make sure they turn off the plane's gust lock before turning on the engines. It cautioned that the throttle could still be movable "if proper unlock procedures are not followed."

One expert's report Wednesday says that investigators found a pair of metal-framed aviator's sunglasses inside the housing of the gust lock, a pair that might have fallen in a few years before. The report said the sunglasses impeded the movement of the lock in simulations.

In other analysis, investigators focused on a key pin of the gust-lock handle, finding it to be damaged.

A spokesman for Gulstream said the company would have no comment.

The accident killed Katz, 72, just four days after he had won an auction for ownership of The Inquirer, the Philadelphia Daily News and Philly.com. After making his fortune in business and law, Katz had become a major charitable giver, pledging millions of dollars to Temple University, the Dickinson School of Law and others.

Others killed in the crash included three friends of Katz - Susan K. Asbell; 68, Marcella M. Dalsey, 59; and Anne B. Leeds, 74

The crew members were pilots Bauke "Mike" De Vries, 45, and James McDowell, 61, and flight attendant Teresa Ann Benhoff, 48.

Tuesday's report stated that De Vries served as pilot for the fatal flight and McDowell was his copilot. It said the two men, both skilled, often traded roles.

DeVries had flown a total of 11,000 hours. McDowell had flown 18,000 hours. Both had worked for Katz for more than a decade.

A toxicological report said that neither pilot had drugs in their system. In DeVries' case, there was a trace reading of ethanol.

Lawyer Arthur Wolk, who represents the families of two victims in the crash, said the reading was likely attributable to the fire's effect on the body.

According to the cockpit transcript, precisely one minute passed from the time a pilot spoke out about a problem until the crash.

DeVries first spoke up about aircraft trouble at 9:30 p.m. when he noted, "The rudder limit light is on."

This warning goes on when the rudder and elevators are locked.

"Are you using your rudders?" McDowell asked.

"No," came the reply.

"Huh."

Nonetheless, the pilots kept advancing on the takeoff, increasing power, according to the transcript.

Some 36 seconds after the first mention of the rudder light, McDowell said "V1" - the last point at which a decision can be made to safely abort or take off.

"Rotate," McDowell said a second later, indicating it was time for De Vries to pull back on the yoke to take the plane aloft.

Over the next 12 seconds, DeVries repeated: "Lock is on. Lock is on. Lock is on. Lock is on. Lock is on. Lock is on. Lock is on."

Another two seconds passed.

"I can't stop it," DeVries said.

A triple chime sounded from the cabin - likely an emergency signal.

"Oh, no, no," DeVries said.

Less than three seconds later there was the sound of impact.

And one second later, the tower officer at Bedford Airport declared: "He's in flames at the departure end."

Victims of plane crashes or their relatives have up to two years from an accident to file lawsuits. So far, relatives of two victims have brought suits.

The family members of Leeds and Dalsey have filed a lawsuit in Philadelphia courts against Gulfstream; other makers of parts and controls for the plane; and the company owned by Katz and a Katz friend who owned the jet.

Wolk, the lawyer representing the families of two victims, said Wednesday's report was incomplete and "raised more questions than it answered."

"If you want to blame dead pilots," he said, "it's a great report."

He said the report's investigation of the plane's gust locks showed that the system is "clearly an inconsistent and problematic component of an extremely expensive airplane."

As for the pilots' alleged pattern of skipping preflight checks, Wolk said the data device may not have captured all of their activity.

Earlier on May 31, the Gulfstream left its Hanger No. 9 at New Castle County Airport near Wilmington and flew to Atlantic City, an eight-minute hop. After Katz and his South Jersey passengers boarded there, the plane took off again and landed at Hanscom Field, in Bedford, Mass., at 3:44 p.m., waiting there for its passengers to return.

The plane had flown for 4,950 hours over its 14-year life. In all, Gulfstream, a subsidiary of General Dynamic, built about 500 Gulfstream IV's between 1987 and 2003. More are still aloft. Accidents involving the Gulfstream are extremely rare.

The crash in Massachusetts was only the 18th accident involving a Gulfstream IV. It was only the fourth time a crash resulted in death and the second time a Gulfstream IV has crashed on takeoff.

The plane's relative safety is also borne out by statistics. Over the last five years, Gulfstream G-IV jets have had about one accident for every 600,000 hours flown. In contrast, the industry wide rate for all such business jets is 2.6 accidents per 600,000 hours aloft.

215-854-4821 @CraigRMcCoy