Airline telephone reservation sales agents use computers to obtain readouts showing seat availability on specific flights.

Petra Gibbons, 33, telephone sales agent for United Airlines since May 1978, has never seen a computer. She is believed to be the airline industry's first and so far only blind reservation agent.

"When Petra applied for the job, there was doubt in the minds of most people that a blind person was capable of handling the job," said Ed Piper, United's Manager of personnel.

For Piper, Petra's desire to get the job had special meaning. His mother and father were both blind.

"After meeting Petra and seeing her demonstrate her ability, there was no question in my mind that she would be successful," Piper said.

But special equipment had to be designed to enable Petra to "read."

And with it she has been able to perform with the same degree of speed and efficiency as her sighted coworkers.

Petra punches the computer keys for flight information like the other agents.

But instead of reading the information on the screen, she moves a small camera mounted on a metal bar tracking guide across the screen.

The camera transmits the images to an Optacon reading machine, a device resembling a cassette tape recorder.

The device converts the photographed letters and numbers appearing on the computer screen.

Thus she "reads" the information through her finger.

In an eight-hour shift she handles from 90 to 150 reservations, the same workload as her colleagues at United's reservation center here.

"Getting this job is a dream come true," Petra said. "Ever since I was a little kid I have always wanted a job with an airline so I could travel.

"Her job with United entitles Petra and her seeing-eye German shepherd, Gypsy, to pass privileges in commercial airlines for trips in the United States and abroad.

What does travel mean to someone who has spent her entire life in total darkness?

"I soak up all the sounds, the smells the atmosphere . . .

"Oh, I can't see Central Park, but I know what it's like riding through it in a horsedrawn carriage. Everywhere the sounds and smells are different," she explained.

"I've had a number of good jobs. But every one I've ever had I got because I am blind. I always wanted a job in spite of my blindness," Petra said.

Gypsy is always by Petra's side even during her working hours. The guide dog was issued an employe's identification card similar to those issued all reservation agents. In the space for a signature is Gypsy's paw print.

Petra reached down, petted Gypsy, grinned and said:

"Gypsy is the only reservation agent I know of who has never produced a booking and gets away with sleeping on the job."