Pensiero said he saw one person taken away in a stretcher and another person, a flight attendant, wearing a neck brace.
He said a fellow passenger told him he saw the stewardess fly into the air "like it was a movie" and hit her head on a side wall, cracking the hard plastic interior. Pensiero said the woman was conscious when he got off the plane.
Another flight attendant told him, "I've been doing this for 20 years, and I've never been through anything like that."
Pensiero, of Moorestown, works for a defense contractor and was leaving for a one-night business trip. After takeoff, the plane broke through a cloud layer into blue skies that eventually turned gray before it hit turbulence at 17,000 feet.
Bill McGlashen, a US Airways spokesman, said the pilots received reports of light turbulence before hitting an unexpected severe patch. The seat-belt sign was still on at the time.
"Somebody described it as being on the 'ride of doom,' where the floor drops out and you drop," Pensiero said. "There were a lot of people on that flight who thought, 'Oh, that's it.' "
After the pilots steadied the plane, they asked the passengers whether any medical professionals were aboard, prompting two people to volunteer. They then announced the plane would return to Philadelphia.
"We're all happy to be back on the ground," Pensiero said by phone from Philadelphia International Airport.
Stacy Jackson, an airport spokeswoman, said another plane carrying the shaken passengers took off at 8 p.m., bound for Orlando.