MANILA, SEPT. 28 -- More than seven years after former opposition leader Benigno Aquino was gunned down at Manila's international airport, three military officers and 13 soldiers were convicted today in his assassination. But the verdict left many Filipinos dissatisfied.

After a 3 1/2-year trial that came to symbolize the slowness and inefficiency of the Philippine judicial system, a special three-judge court found the 16 military men guilty of murdering Aquino, husband of the nation's current president, Corazon Aquino.

The military personnel also were convicted in the slaying of a man, described as a small-time hoodlum, who had initially been accused of killing Aquino but was later found to have been framed. Twenty others were acquitted, and the verdict failed to clarify who ordered the killings.

The court announced the verdict on the first anniversary of the death of former president Ferdinand Marcos, a bitter political enemy of Aquino. Marcos was deposed after a popular uprising in 1986, and he died in exile in Honolulu.

The assassination of Aquino, who was jailed by Marcos for nearly eight years and sent into exile in the United States, became a landmark event in the Philippines and helped to unify forces that eventually overthrew Marcos in February 1986.

Today, the airport where Aquino was slain is named in his honor, a statue depicting his assassination stands in Manila's financial district, and his widow, who took office after Marcos's ouster, is serving a six-year presidential term. Her husband was killed Aug. 21, 1983, as soldiers escorted him from an airliner on his return from exile.

In a statement today, the grim-faced president said she sometimes "found it difficult to understand and explain, especially to my children, the sluggish pace of justice." As Benigno Aquino's widow, she added, "I do have very strong feelings about the verdict. However, my position as president prevents me from expressing my true feelings."

A presidential spokesman, Horacio Paredes, accused Marcos of arranging the assassination. "The mastermind died a year ago today," he said, "and history will have to judge him, not the courts." People interviewed by Philippine news media after the verdict expressed dismay that the major question in the case had not been resolved.

The court concluded that the 16 military men convicted deserved the death penalty, but sentenced them to life imprisonment because of the 1987 constitution's ban against capital punishment. They also were ordered to pay $300,000 to Aquino's heirs and $22,300 to the heirs of Rolando Galman, the man believed framed in Aquino's slaying.

Galman was riddled by bullets on the airport tarmac seconds after Aquino was killed with a single shot to the head. The Marcos administration asserted that Galman had assassinated Aquino on behalf of Communist rebels.