John Hubbard caught Air Florida's Flight 90 out of National Airport yesterday, one day later than originally scheduled. For him and several other passengers, boarding the plane was a somber reminder of their close call.

"I was scheduled to take the flight and I normally fly Air Florida because it's the cheapest," said Hubbard, a 47-year-old U.S. Postal Service worker from Gaithersburg who regularly commutes to Tampa on government business.

But unknown to either his office here or in Tampa, Hubbard canceled his booking as weather conditions worsened Wednesday. It wasn't until worried coworkers began calling his home that he learned how close he had come to tragedy.

"I was pretty shocked, kind of stunned," said Hubbard, whose postal service colleague, attorney Donald Gilmore, is among those presumed dead from the crash. "Then I turned on the TV--it was bad."

A nervous Hubbard boarded the flight yesterday, reasoning that "if you don't go back up a second time right away, you won't ever go."

At National yesterday, Flight 90 took off--amid another snowstorm --about 15 minutes after its scheduled departure time of 2:15 p.m. The plane for the flight, which can hold 125 passengers, carried 53. Some airlines have been known to renumber flights after a crash, but an Air Florida official at the gate said the airline hadn't really considered any change.

Passengers aboard that and other Air Florida flights left National either unconcerned about their safety or only slightly jittery.

"It can't happen two days in a row, but I wish it would stop snowing," said Christy Anastasi, 22, a Rockville resident en route to Fort Lauderdale for a vacation.

Earlier in the day passengers had waited at airport gates, scanning newspaper articles and photos of the Boeing 737 crash and talking nervously of the accident. By Flight 90's departure, the talk was of narrow escapes.

"I guess it was not my time to die, yet," mused Mrs. W. K. Scott, a Bethesda resident who had booked herself on Wednesday's Flight 90 but changed her reservation several days ago after her son in St. Petersburg decided a Thursday arrival would be more convenient.

Fort Lauderdale resident Frankie Thomas, in Washington to visit her daughter in college, had initially asked to return on Flight 90 Wednesday, then switched to Thursday at the casual suggestion of her sister. Stanley Reed of Vienna, had planned to leave on vacation Wednesday, but decided he "didn't want to take off another extra day."

Dorothy Bush, 65, who as secretary of the Democratic National Committee calls the roll of states at party conventions, returned to her home in Naples, Fla., yesterday, glad that her husband, John, a former Interstate Commerce Commission chairman, had switched from his Wednesday Flight 90 booking to a departure earlier in the day.

"He decided it was bad weather, and he should get on home--thank goodness he changed," Bush said.

But perhaps the eeriest "what if" story came from Jane Dodge, 31, a high school counselor from St. Petersburg. She missed the Wednesday Air Florida flight because ice forced the Charlottesville airport to close. Coming into Washington by train yesterday, she passed the grim crash site that might have been her watery grave.

"That," Dodge said, "was scary."