BY OSCAR CORRAL

Forty-five years ago, Nestor Pino opened the back door of the C-46 airplane zipping low over the Bay of Pigs. The fleet of U.S. ships lined up along Cuba's coast gave him confidence. He had a single thought: ``There's no way we can lose.''

Pino led the CIA-backed paratrooper assault for Brigade 2506 in the failed Bay of Pigs invasion, one of the biggest military debacles in U.S. history. Cuban troops captured almost 1,300 of the invaders, and 104 lost their lives before, during or after the attack. Cuba maintains the exiles killed about 150 of Fidel Castro's men, although various U.S. estimates place Cuba's casualties much higher.

Today, almost half of the 3,000-plus men from Brigade 2506 are dead. The ones who are left don't want their cause to be forgotten. They are hosting a reunion tonight at the Coconut Grove Expo Center, where they were reunited with their families in 1962 after Cuba freed them from prison. It is the largest reunion since the 1960s, said Brigade President Felix Rodriguez.

Bay of Pigs veterans, intent on leaving a legacy, also are raising money for a $10 million multimedia museum in Little Havana. The museum, with interactive displays, will explore the invasion in the context of the Cold War and follow Cuba's attempts to internationalize its communist revolution.

The attack by Cuban exiles and some Americans at the Bay of Pig's beach at Playa Giron -- to try to take back Cuba country from Fidel -- was a historic turning point with deep roots in Miami.

Because of the failure, Castro consolidated his power, the Cuban missile crisis terrified the world a few months later, and the Soviet Union kept a beachhead in the Americas to export Marxist guerrilla movements around the Western Hemisphere for decades.

''It just wasn't an appropriate place for a landing,'' said Pino, who now lives in Virginia.

During a Miami visit this week, he mulled over the reasons for the failure of the assault: ``The original plan was to land in [the Cuban city of] Trinidad, where there was much better beaching and an airport. . . . Our forces got caught up on the coral reefs and had to carry all the supplies to land.''

President John F. Kennedy's handling of the invasion is also the root of Cuban Americans' inclination toward the Republican Party. Many Brigade 2506 survivors still blame Kennedy -- and the Democrats -- for failing to provide proper tactical support.

But as they age, Bay of Pigs veterans have learned to put the loss in perspective, if not shed some of the resentment they still harbor for Kennedy.

Felix Rodriguez, 64, was just 19 when the CIA trained him to infiltrate Cuba through Trinidad in advance of the invasion. Among his team members: future Miami-Dade County Commissioner Javier Souto. From Trinidad, Rodriguez went to Havana, where he was when the assault took place. When he realized the invasion had failed, he said, he sought asylum in the Venezuelan Embassy.

Rodriguez had wanted to be an architect. Instead, he stuck to a military and CIA career. He was among three Cubans working for the CIA who led the capture of Ernesto ''Che'' Guevara in the Bolivian jungle in 1967. Castro had sent Guevara, the charismatic Argentine and Cuban revolutionary leader, to Bolivia to recruit peasants for a populist revolt.

''It changed all of our lives, but I don't regret anything,'' Rodriguez said. ``I've had an interesting life and feel happy with what I've done.''

Many of the veterans still consider themselves to be in a state of war with Cuba. Like Rodriguez, some joined the armed forces after the Bay of Pigs and formed close bonds with the U.S. government. Others stayed with the CIA, and eventually broke off in their own paramilitary groups to run anti-Castro raids against Cuba.

Three of the Brigade members are in the media spotlight in Miami, this time because they are in trouble with the U.S. government. Luis Posada Carriles, who never disembarked at the Bay of Pigs, is in federal custody in El Paso, Texas, after he sneaked into the United States last year; he is accused by Venezuela and Cuba of terrorist acts. Posada's benefactor, developer Santiago Alvarez, is now facing federal weapons charges, along with Osvaldo Mitat.

Along with other exiles, the three continued the violent struggle against Castro long after the Bay of Pigs. But many don't see that as a viable option today.

''I respect everyone who wants to fight to liberate Cuba, but I personally feel that the violent fight to free Cuba at this moment is not feasible,'' said Bay of Pigs veteran Eduardo Zayas-Bazán, professor emeritus at East Tennessee State University. ``I don't see that the Cuban regime can be overthrown with an invasion.''

Zayas-Bazán, a CIA-trained frogman, was among the first five exiles who went on shore with Grayson Lynch, an American who later wrote one of the invasion's most definitive books.

For most of the Brigade veterans, violence no longer plays a role in their anti-Castro outlook. But that doesn't mean they've softened their position on his government.

Brigade 2506 member Esteban Bovo, whose son Esteban ''Steve'' Bovo is a Hialeah city commissioner, bristles when he thinks of anyone trying to have a dialogue with Castro.

''As long as Castro is in power, we remain in the same state of war,'' Bovo said.

Not all Brigade 2506 members feel the same way. Five years ago, a small group of Bay of Pigs veterans decided to break with the group to promote open dialogue with the Castro government. At least two of them, including Mario Cabello, were expelled from the veterans association for traveling to Havana to participate in a conference about the failed mission during the 40th anniversary.

Not a day goes by that Mattias Farias, a Spanish language radio commentator on WWFE 670 AM La Poderosa, doesn't think about the day his B-26 was shot down over the Bay of Pigs, killing his co-pilot and forcing him to crash-land near the beach's airstrip.

After the attack, Farias joined the U.S. armed forces and rose to the rank of colonel, learning in military college that the plan for the invasion had ``28 major mistakes.''

''Would you like to hear a few of them?'' he asked. "You never disembark for an amphibious invasion at night. You do it between 5 and 7 a.m. You don't do it without anti-aircraft battery. Our tanks were tanks for reconnaissance, not combat.''

So many details could have been tweaked, so much more help given. And in the end, Castro's army crushed the invasion. Most of the exiles were captured, then released the following year in an amnesty and reunited with family in Miami's Dinner Key Auditorium, now the Coconut Grove Expo Center.

''I don't look back to Giron with regret,'' Farias said. "I don't blame anybody.''