NEW ORLEANS -- Twelve Mile Point is just above the Huey P. Long Bridge on the Mississippi River. The river is 2,000 feet wide there, very deep and a main thoroughfare of one of the last independent breeds of riverboat kings.

Twelve Mile Point is also where a 600-foot cargo ship collided with a tug towing eight barges on a moonless evening in October 1986. No one was injured, but the collision set off one of the greatest river battles between the locals and the federals since Mark Twain plied these waters on the eve of the Civil War.

The ship was piloted by Capt. Robert M. (Mickey) Karr, a veteran riverman of three decades who has had his share of trouble on the river recently. The collision at Twelve Mile Point was his sixth accident in five years. Two of them involved ships carrying hazardous cargo. Accidents involving Karr have caused more than $20 million in damage to ships, boats and docks.

Why Karr had trouble at Twelve Mile Point has been debated at length for more than a year. He has been unavailable for interviews while the accident investigation is pending, and the debate has escalated into a war between the National Transportation Safety Board (NTSB) and river pilots about state's rights.

"A guy may have two, three, maybe half a dozen accidents in 25 years," said Capt. Joe Clayton, president of the New Orleans-Baton Rouge Steamship Pilots Association, known as NOBRA. "This pilot never had an accident in 35 years. Then, the luck of the draw hit him five years in a row. If you average it out, it's not different than anyone else over the course of a career."

Another captain, Charlie Pomansky, said, "If it were me, I'd take my keys out of my right pocket and start carrying 'em in my left pocket. That's about all you can do."

The NTSB took a different view of averages and luck. The board rarely investigates ship accidents, preferring instead to leave them to the Coast Guard, which is required to investigate all marine casualties. But after Karr's sixth accident, the NTSB stepped in.

"The key was recognizing that Mickey Karr had been involved in five major accidents in which it appeared that some form of judgment was involved," said John Lauber, the NTSB board member who headed the investigation. "What we wanted to know is who's monitoring the performance of these river pilots? Is there any investigation anywhere? It's a question of supervision and oversight. Who's doing the quality control?"

The NTSB did not anticipate that its instrusion into the extraordinarily private world of river pilots would set off fireworks to rival those at Mardi Gras. The accident has come to seem almost a side issue to the dispute. After 15 months of squabbling, the battle is more about how private this most private of clubs would remain.

"I was dismayed with the reception and cooperation, or the outright lack of cooperation," Lauber said after a four-day hearing about the accident in New Orleans turned into a skirmish. "The issues tended to get lost in the acrimony of the thing."

Pilots at the hearing were reluctant to share information about their own accident investigations or to detail internal disciplinary procedures.

When NTSB investigators and Karr came face to face in the hearing room last January, Karr punctuated the exchange with a series of caustic one-liners that provided little information and came to symbolize the resentment that the pilots said they felt at the federal investigators' probing of their internal affairs.

Asked, for example, for what vision defect his eyeglasses were prescribed, Karr replied: "To see with." Asked how often he consults maps and charts, he said, "Just when I want to know something." How did you learn to turn a ship? he was asked. "Thirty years' experience. Trial and error," he replied.

At the hearing, Capt. Martin Gould, NOBRA chairman, told investigators that "a series of accidents, you understand, has really nothing to do with it."

"If a pilot was incompetent yesterday, you cannot prove that he is incompetent tomorrow," he said. "He is the same as a baseball player. Mickey Mantle struck out four times yesterday, but he hit four home runs today."

When the NTSB finally went into federal court last fall to obtain a copy of the NOBRA's bylaws and records of Karr's last eye examination, it was opposed by the state of Louisiana. The state contended that the board's actions "could cripple and destroy an already weakened economic situation" and said "there is nothing broken here in Louisiana, hence your board has nothing to fix."

The NTSB plans to meet in Washington Tuesday to decide if it should recommend changing the way pilot accidents are investigated.

Ship pilots are an independent, storied breed, popular in American literature and romanticized through 200 years of maritime folklore.Benevolent Monopolies

Pilots also belong to one of the most exclusive, inbred work societies in the American economy. They form benevolent monopolies, controlling movement of about 95 percent of ships traveling to and from American ports. No foreign-flagged ship can enter inland waters on its way to port without a pilot to guide it.

The pilots set fees. They control their wages by limiting the size of the membership. Wages are good and always have been. Mark Twain described his pilot's salary as "princely." Capt. Douglas Grubbs, who works the river below New Orleans, still tells the story about the day he decided to become a pilot. He was a young deckhand on a tug and watched a pilot climb down the rope ladder, he said. Grubbs was wearing boots. The pilot was wearing alligator shoes. Grubbs said he needed no more convincing.

The salary range these days is between $90,000 and $115,000 a year. There is no mandatory retirement age.

"Piloting is the pinnacle of the inland water operation, and the pinnacle of piloting is ship piloting," Clayton said.

On the lower Mississippi, pilotage predates 1878, the year when the Associated Branch Pilots organized and began charging sea captains for threading their sailing ships through the narrow, treacherous channel from the Gulf of Mexico.

Paul Cucullu, a member of the branch pilots, said he began by piloting converted Liberty ships left over from World War I. Tom Mailey, who lives at Pilottown, the pilot station near the delta, said he went to sea at 17.

Now, three pilot associations control foreign ship traffic between the gulf and Baton Rouge. The NOBRA is the youngest of the groups, formed in 1927 when Exxon built a dock at Baton Rouge.

NOBRA pilots handle ship traffic on the 143-mile stretch of the river between New Orleans and Baton Rouge, through a thicket of oil refineries, past such old sugar plantations as White Hall and a place known as Kamikaze Alley, named because of the erratic maneuvering sometimes required when a huge barge fleet moored there.

"Piloting is an art, it's not a science," Gould said after NTSB probers returned to Washington. "The government can't treat it from a scientific approach. If they do, they're making a mistake."

This "art" involves knowing the way the river "feels," how eddies and currents are read, how the shoreline should be followed in fog, how to know when the ship's keel is too near the bottom and in danger of running aground.

"She'll get a lot of vibration," Capt. Gary Mott said. "All ships feel it in the engine room. She'll take more wheel to keep her steady, and she'll tend to try to find the deepest part."

Cucullu said, "They used to take 'em up in the fog and use the whistle to get echoes off the bank. If the sound you hear bounces alongside, you're parallel to the bank. If it's ahead of you, you're headed into it. The quicker it comes back, the closer you are."

There is an old story about the pilot who guided a ship up the river in dense fog by listening to the croaking sounds made by frogs on the banks. And there was the pilot who smoked cigars with a wrapper that read: "Where the river flows, he goes." There is also the pilots' storied saying: "A pilot's not a pilot until he's bent metal."

"I had a little incident a while back," Mailey said. "First time I went to court. The lawyer says, 'How did you know you had enough room to pass the towboat?' And I says, 'You wouldn't walk through a closed door, would you?' and he says, 'No.'

"And I say, 'Well, I wouldn't try to drive a ship through a place where there's no room.' "

Mailey shrugged, as if he thought that the lawyer was pestering him unnecessarily: Did he think riverboat pilots have accidents on purpose?

"They're used to the steamboat inspection people. They had practical people. They'd say, 'What happened?' and I'd say, 'She didn't make the point.' "

This kind of mood about accident investigations extends throughout piloting, in part because river pilots have remained independent of federal regulation since 1851, when the Supreme Court, in deciding a Philadelphia case, ruled that the states should regulate pilots.Pilots Supervise Pilots

Since then, the Coast Guard has tried to gain jurisdiction but has never succeeded. The Coast Guard investigates all marine accidents but has no jurisdiction on the Mississippi River, a state waterway. Therefore, its recommendations have no teeth.

Instead, the three pilot associations are supervised by three pilot commissions, each made up of three pilots. The commissioners are appointed by the governor and serve two-year terms. The pilots say that they are unaware of the activities of their counterparts and that accident investigations are conducted in secret. Yet the pilot commissions share office space with the pilot associations.

In Louisiana, the agency charged with investigating the accident at Twelve Mile Point was the NOBRA.

The NTSB questioned the effectiveness of the group investigations. The questioning became particularly intense after the federal officials learned that Karr was neither disciplined nor reprimanded after his previous accidents, despite the NTSB's finding that he had contributed to the cause of at least two of them.

When the NTSB convened the four-day hearing in New Orleans a year ago, Lauber said, he was surprised to find leaders of the pilot association, the pilot commissioners and representatives of the governor's office -- the investigators and the investigated -- sitting at the same witness table.

The pilots say no one is better qualified to judge pilots and performance on the river than pilots who work the same route.

"You have a lot of organizations where people are judged by their peers," said Capt. Mark Delesdernier, a third-generation pilot and president of the Crescent River Port Pilot Association, which works the river below New Orleans. "The bar association of Louisiana would be one example."

Pilots in the two other pilot associations have watched the proceedings with some uneasiness, and have quietly distanced themselves from the NOBRA. The Crescent River Port pilots talk openly about their drug and alcohol testing program and their guidelines for accident investigations.

"I would have preferred that NOBRA have handled their matters a little differently," said Grubbs, president of the Crescent River Port Pilots Commission.

NOBRA pilots said the dispute is a matter of principle. To them, it is about an abuse of power by a federal agency, despite the fact that NTSB recommendations are not binding. "This is America," Gould said. "I have a hell of a hard time understanding how Washington could allow these people to have that kind of power."

Clayton said that the current system works well and that safety must be merged into the economics of the industry, as he thinks is being done successfully under the tight-knit system that the Louisiana pilots run for themselves without federal help.

The underlying fear evolves from that very point. On the river around Twelve Mile Point, the deepest concern is that the dispute might provoke changes in the exclusive pilot clans when economic hard times are causing enough trouble. Shipping revenues have dropped by 31 percent since 1982.

As long as the pilots can keep at bay those whom they see as troublesome outsiders, their exclusive clubs can keep riverboat life on a relatively even keel.