GOLDEN, Colo. (AP) _ Two survivors of the Nov. 15 Continental Airlines crash at Denver's airport told investigators Tuesday that they thought they saw ice and snow on the wings as the DC-9 took off in a swirling snowstorm, but a pilot on another plane said the Continental jet looked clear.

Moments after takeoff, the jet flipped over, hit the runway and broke into three pieces, killing 28 people and injuring the other 54 people aboard. Some victims were trapped in the wreckage for more than six hours.

Wes Zimmerman, a Continental pilot on a neighboring plane that day, and crash survivors Dr. Fred Helpenstell, 56, of Nampa, Idaho, and Gregory Wadsworth, 22, an airman stationed in Idaho, were among 29 witnesses scheduled to testify at the National Transportation Safety Board hearing, which opened Tuesday.

De-icing and the pilots' experience flying DC-9s were the chief issues raised during early testimony, although government officials have said their inquiry is not focusing on a single possible cause.

Zimmerman, whose Continental 727-300 aircraft was on the 35-L runway at the same time as the Continental jetliner, said he saw no ice or snow buildup on Flight 1713.

''I felt good about how my de-icing was holding up,'' he said, explaining that he looked at nearby aircraft to gauge the condition of his own plane. But he acknowledged that his plane did not sit for as long between de-icing and takeoff as the ill-fated plane had sat.

Robert Benzon, the NTSB investigator in charge of the inquiry, said during his opening statement that officials want to know why 24 minutes elapsed between the time Flight 1713 was de-iced and the time it took off. Other planes on the runway were taking off 15 minutes after being de-iced, he said.

''The reasons for Flight 1713's 24-minute delay and the possible effects of snow or ice buildup on the wings and tail surfaces of the airplane during this delay are items of interest during this hearing,'' Benzon said.

In addition, the pairing of the two flight officers aboard Flight 1713 would be discussed during the hearing, he said.

Capt. Frank Zvonek, 43, who had 198 hours on a DC-9 with only the previous 33 hours as captain; First Officer Lee Bruecher, 26, had 36 hours piloting DC- 9s and was flying the plane at the time of the crash. Both men were killed.

''The pairing of two pilots with such experience in an aircraft type will be discussed during this hearing,'' Benzon said.

Helpenstell, who suffered broken ribs and a broken finger in the crash, told the board that during takeoff from Stapleton International Airport he noticed that a wing looked wet.

''I wondered at one point, 'Is that ice?''' Helpenstell recalled, ''but I decided it was just wet.''

Wadsworth, who is stationed at Mountain Home Air Force Base in Idaho, said he had a clear view of the left wing.

''It had started to snow a lot harder, and it made me real nervous. It was like the snow was starting to pile up (on the wings),'' he said. ''I was very concerned, but I said it under my breath. I figured they do it (taking off in snowstorms) every day, and I was hopeful they would be able to do it this time. But unfortunately, that was not what happened. It was bad place.''

Continental officials criticized Wadsworth's testimony during the hearing, noting that he had lost a certification as an Air Force mechanic. Wadsworth said he had been temporarily removed from mechanic duty because he had suffered flashbacks of the accident while he was on duty. He now works in a tool room.

Zimmerman, who had flown a DC-9 from June 1985 to February 1987, testified that before shortly before the Stapleton crash, light to moderate snow was falling, not enough to affect safety.

He said snow accumulation on his aircraft was ''very light. It was a cold snow, not a wet snow. It didn't build up on the flat surface of the wing.''

He testified that Continental does not require pilots to have planes de- iced, but leaves it to the pilots' discretion. He estimated the time between the de-icing of his plane and takeoff at 17 to 18 minutes.

Under questioning by federal investigators, Zimmerman said that if he had had to wait five minutes longer for takeoff, he would have re-evaluated whether his plane needed de-icing.

Flight attendant Kelly Englehart, 35, testified she was concerned when she learned that Bruecher would be flying the plane. She and Helpenstell also gave conflicting versions of the direction in which the aircraft rocked before it crashed.

Helpenstell said the plane rocked first to the right side on which he was seated and then came back suddenly to the left. Englehart said the DC-9 rocked first to the left side and then sharply to the right.

''We felt the wing must have hit then. There were three large pops and a large explosion. I saw a large, orange fireball at the front of the cabin moving down. I shut my eyes and waited for it to be over. I waited for it to get me,'' she said.