COLORADO SPRINGS, Colo. (AP) _ A data recorder taken from a United jetliner showed the plane's approach to the city airport was normal until the last six seconds, when it plunged nose first into a park, an investigator said Tuesday.

The recorder, recovered from the wreckage, revealed the final 45 seconds of Flight 585 last Sunday.

''Everything was pretty much steady state until the last six seconds. Everything is normal. Nothing is out of the ball park until the last six seconds,'' said John Lauber, a National Transportation Safety Board investigator.

The jet's air speed jumped from 160 knots to 213 knots and altitude decreased rapidly in the final seconds before the crash, which killed all 25 people on board, he said.

Lauber said an evening briefing that a second recorder, the cockpit voice recorder, suffered significant damage and investigators don't know how much information will be obtained from it.

As residents looked on earlier Tuesday from a nearby apartment complex, investigators dug up pieces of embedded wreckage of the jet.

The smell of burned plastic still hung in the air Tuesday, two days after the Boeing 737 came down at a sharp angle five miles short of Colorado Springs Municipal Airport, burying much of itself in the ground.

Federal officials, who said it was too early to conclude that air turbulence, pilot error or low fuel supply might be to blame, examined flight data and cockpit recorders Tuesday.

Debris was scattered across an area about the size of a football field after the plane crashed in a small park in the Widefield community in the foothills of the Rocky Mountains.

Flight 585 narrowly missed an apartment complex and houses. Residents, some of whom witnessed the crash, watched as a dozen investigators scoured the site.

''It's amazing that there's so much stuff down there,'' said crash witness Donna Boatman. ''On Sunday, I was down there right away. You thought it was a little tiny plane. There's all this stuff now. It looks like a junkyard.''

Another resident, Lisa McDaniels said she was having a difficult time coming to terms with what she had seen. ''All you could do is stand here knowing you couldn't do anything,'' she said.

Workers used a crane to dig deep into the earth to recover charred chunks of the twin-engine plane Monday. By then, the bodies of the 20 passengers and five crew members had been recovered.

Investigators said they were far from determining the cause of the crash. ''It's a game of inches,'' said National Transportation Safety Board spokesman Brent Bahler. ''It's still a wide open mystery.''

Lauber, leader of the NTSB team investigating the crash, said the operation to assemble the evidence needed to reach any conclusions was not yet completed ''but we're mighty close to being as far down as we need to be with it.''

''We're digging down until we're sure there isn't anything major left in there,'' Lauber said.

Officials have said possible causes include wind shear, which occurs when wind speed reverses across a plane's wings and causes the plane to drop rapidly.

Lauber warned against assuming the accident occurred because of wind shear, but severe wind shears have been recorded in the area, where cold air sweeps down from the Rockies into the plains.

Feathers were found on small pieces of wing, Lauber said. Collisions with birds or instances in which birds were sucked into jet engines have caused plane crashes, but he said that was unlikely in this case.

Witnesses have said the plane was making its final approach for a landing when it pitched downward and rolled right, Lauber said. Wreckage was buried at least 16 feet into the ground.

As they examined pieces of the plane Tuesday, investigators looked for the position of the screws on the wing flaps to determine where the flaps were set.

''We want to make sure we didn't have any pre-existing failure of some sort,'' Lauber said. ''So we have to look at all those things in detail to make sure everything is accounted for.''

Bahler said investigators will also be concentrating on the plane's actuators, or gears, ''to tell us how the plane was configured on its final approach.''

The co-pilot, Patricia K. Eidson, 42, was believed to be the first woman pilot or co-pilot of a major commercial airliner to die in a crash in the United States.