One year ago today, Washington fell victim to two catastrophes so swift and sudden that they seemed like orchestrated acts of vengeance. With brutal dispatch on a snow-blind afternoon, 81 travelers--in an airplane, in cars, and in a subway train--were killed or suffered fatal injuries.

The bare details, 12 months later, seem implausible:

A Florida-bound airplane takes off from National Airport and within seconds swoops down out of a snowstorm into rush-hour traffic on the 14th Street bridge. It slashes through six cars, a truck and 40 feet of guardrail. At 150 miles an hour, it nose-dives into the icy Potomac. Seventy-seven people are killed.

Thirty minutes later, a subway train derails beneath the Mall. A car is crushed against a concrete pillar. Three are killed in the first fatal accident in the history of Metro.

Meanwhile, in the paralyzing cold of the river, six survivors cling to sinking wreckage. One of them passes a rescue line to his fellow survivors and then drowns. A bystander throws himself into the water to save one survivor and becomes an instant national celebrity.

A year after this script was enacted, the horror that pervaded Washington on Jan. 13, 1982, has long since dissipated. After coroners and air-crash experts and special investigating panels picked over the corpses and sifted through the wreckage, the prosaic causes behind the spectacular tragedies were uncovered. Human error, not divine vengeance, was responsible. "This wasn't an act of God," said one of the lawyers involved in the suits.

The two young pilots of Air Florida Flight 90 made three critical mistakes taking off in the ice and snow, a National Transportation Safety Board report concluded. The report said the pilots misjudged the danger of ice on the wings, set throttle power too low because they had failed to switch on an engine warming device and did not abort the takeoff despite clear signs of trouble.

In the subway tunnel, investigators found that the driver, a supervisor and control room experts all violated safety procedures. In the last year, Metro has improved training and revamped safety procedures.

While aviation rules have changed little since the crash, pilots around the country have become more aware of the danger of flying in winter weather. The acrimonious feud over closing down National, the convenient airport that Congress refuses to phase out, flared anew for months after the crash. Today, as the arguments simmer, flights at National have increased slightly. Air Florida, after a temporary loss of customers and the canceling of Flight 90, reports that business is about the same as in 1982.

As last year's double-edged disaster passes into history, it will be noted that the death toll did not reach that of Washington's worst catastrophe when 96 people died after a snowstorm collapsed the roof of the Knickerbocker Theater in 1922.

Echoes of last year's tragedy, however, are likely to be heard for years in this city. The deafening growl of low-flying jets on the Potomac evokes the disaster every day. For the five who were plucked from the river, the echoes will always be laced with terror.

Survivors of Air Florida Flight 90 have lived the last year with an overwhelming consciousness of cold. Bobbing in the river, which was fouled with jet fuel and clogged with ice, was like "being encased in ice-cold metal," says Patricia Felch, 28, a Herndon secretary who contracted a rare infection in the river that has eaten into the bones of her right instep.

Felch smells jet fuel at odd hours. For Bert Hamilton, 41, of Gaithersburg, faces on television become faces he saw on the plane. Priscilla Tirado, who lost her husband and baby, hears the awful metallic crack of the plane hitting the bridge. And Joe Stiley, 42, a Manassas executive, remembers the freezing water in the plane rising up to swallow him "in total blackness." When he fought free of the plane, he broke through to the surface of the river and saw only a few sheets of paper and scraps of yellow insulation. The plane "was just--gone."

Kelly Duncan, a flight attendant, turned to God this last year, returned to flying and decided not to sue. The others, who are suing, are more troubled--unable to ignore the flimsy contingency of their lives.

The relatives of those who died a year ago today have been dreading this anniversary and the grief it will elicit.

Many of them are still angry at the two pilots of Flight 90. Others are angry at disc jockeys who made jokes about the crash, and at a host of wrongs, real and imagined. Some simply refuse to accept the macabre bad luck that stole away the lives of persons they loved.

"To be in a car and get hit by a plane, to see it in print on the death certificate--hit by a plane--is horrible," says Bette Spriggs, sister-in-law of Mariella Spriggs, 26, who was engaged to be married and who died when the Boeing 737 crushed her car as it sat in bumper-to-bumper traffic on the 14th Street bridge.

"There are times I wake up in the morning and I hear a noise in the yard or the dog bark and there is a fleeting moment when I think it is Marilyn coming home from a flight," says Larry Nichols, a Miami developer whose wife was a stewardess on the plane.

"You can go from loneliness to disbelief to anger to acceptance, and then back to anger and disbelief," says Nichols.

Grief has turned many to their God; others have turned inward. Fatuma Soune of Alexandria who lost her husband Eugene, said she couldn't talk about his death, saying, "No, no, please. I'm sorry, no."

Relatives of those killed, along with survivors and commuters on the 14th Street bridge, have gone en masse to the courts for redress. So far, 73 suits have been filed, and 21 of them already have been settled out of court. According to lawyers familiar with the case, each family has been paid between several hundred thousand and a million dollars.

The remaining suits are likely to be resolved far faster than litigation from other air crashes, such as the DC10 disaster in Chicago in 1979 for which suits are still pending. U.S. District Court Judge Joyce Hens Green is pushing all parties to meet a March trial deadline.

Lawyers say almost everyone who sues will win and that the total amount of damages could approach $60 million. What's preventing quick payment of all the money is a dispute between two defendants, Air Florida and Boeing, over responsibility for the crash.

Air Florida claims that Boeing knew about, but failed to warn the airline about, the tendency of the 737 to pitch up its nose in bad weather. Boeing says the airline was told about the problem and that Boeing is not responsible for what happened. Boeing and the Federal Aviation Agency are considering modifying the 737 to help correct ice-caused takeoff problems.

In the panicked moments after last year's crash--the first fatal accident at National since 1949, when 61 people died in two collisions a month apart--the airport and local rescue units discovered they were unprepared to save lives when a plane falls in the river.

Survivors in the river remember the agony of being surrounded on the bridge and on the shore by rescuers who could do nothing to help them.

"What they were shouting had no relation to the reality of our situation," says Joe Stiley, who remembers ropes dangling from the bridge that were too short to do anything but taunt him.

Since the accident, boats, radios and rescue nets that allow helicopters to pull four or five people from the river at a time have been purchased.

A year ago, as others stood yelling and doing nothing, two men chose to act without thought to their own safety: Lenny Skutnik, who saved a drowning woman, and Roger Olian, who swam to within five feet of the survivors and turned back when he heard a helicopter.

Last week, Skutnik and Olian returned to the foot of the 14th Street bridge, to the steep rocky bank where they dove into the water. They had their pictures taken and they studied the river.

There isn't any ice on the Potomac this year. No snow on the ground either. The two men, however, seemed awed by the water.

Said Olian: "You couldn't pay me enough to go back in that river."