John Chelena remembers leaning out the fifth-floor window of a Virginia Tech dormitory, straining to get a better look at a building across campus.

Chelena also says he remembers the sharp pain in his back as he picked himself up off the concrete sidewalk 50 feet below.

There just wasn't enough time to be scared," the 18-year-old Vienna youth said in a telephone interview from his hospital bed yesterday. A freshman at Radford College, Chelena was visiting high school friends at Virginia Tech in Blacksburg Friday night when he accidently plummeted to to the pavement.

"When I looked up, it hit me how lucky I was to be alive. All the way down I kept telling myself to keep my head up and try to relax," Chelena said.

Chelena said doctors at Montgomery County Hospital in Blacksburg, where he is being treated, told him that he has a hairline fracture of his back and must wear a brace for six weeks. He apparently suffered no serious or permanent damage. The youth, a 1979 graduate of George C. Marshall High School in Falls Church, also received 20 stitches in his elbow.

Chelena said that he and his friends had drunk "a few beers" prior to the accident, which he said occurred shortly after 10 p.m., but "nobody was near being drunk."

Chelena said that after the fall he and his friends walked a half-mile to the school's infirmary where he was denied admission because he was not a Virginia Tech student. A friend then drove him to nearby Montgomery Hospital.

Last week, in a similar accident, a 19-year-old Catholic University student sustained serious injuries, including a fractured skull, after he fell 65 feet from the roof of a building at that school.

"I think about my accident a lot now," said Chelena, who expects to be released from the hospital later this week and plans to return to classes next Monday. "I'm really thankful to be alive."