Since they defeated the Philadelphia Flyers here by 6-0 on Dec. 21, the Washington Capitals had been slipping almost steadily downhill. Tonight they reversed direction.

With Mike Gartner scoring three goals and Mike Palmateer blocking 34 shots, the Capitals thrashed Philadelphia, 5-2, and leapfrogged both Toronto and Edmonton into 15th place in the National Hockey League.

Gartner's second hat trick this season -- the first was against the New York Rangers Oct. 18 -- boosted his goal total to 44. Dennis Maruk chipped in his 45th and Tim Tookey netted the other.

"That was a bonus tonight," said Gartner, who has scored at least one point in a club-record 13 straight games. "It's not just beating them twice in this building, it's a really important two points. We've been playing playoff hockey the last three games and a win like this is a big boost for the team mentally.

"We've got confidence in our goal-tending now. Gary Inness has been great and Mike Palmateer gave a super effort tonight. Everybody has confidence in the other player and we don't start to scramble around."

Palamateer was playing for the first time since he was chased in Wednesday's 6-4 loss to Quebec, when he heard so many boos in Capital Centre. He received few cheers here tonight and was ignored in the three-star selections, but he was the key to victory. He owns a remarkable record in this building where so few visiting teams are ever successful, having shut out the Flyers on his previous two visits, a year ago with Toronto and in December with Washington.

"We're facing six games in nine days and there's no way Gary, can play all of them," said Washington Coach Gary Green. "We're going to need two goalies and we need to get Palmy back in there. He's had some problems at home, but he's always played well inthis building."

Palmateer, still apparently upset by some comments directed at him in Washington, avoided the joy of the dressing room to sit alone in a tiny adjacent cubicle, where he said, "It was a good team effort, that's all I've got to say. I don't want to talk for a while. Every time I say anything I get myself in trouble."

Much of Palmateer's trouble has come from wandering out of the net and tonight he stayed close, although rarely hesitating to take a couple of strides and send the puck up the ice. The Washington defense stood up well, although it underwent periods of intense Philadelphia pressure, and managed to clear the puck with a minimum of off-target passes.

"We knew there was no way their defense could hold our forwards," said defenseman Pat Ribble. "We just wanted to get rid of it (the puck) quick and get it up to them. I told Palmy before the game not to roam, just to get rid of it quick.

"This is a big lift for us going into the playoffs, to beat a team like that. I've been with a lot of teams and I think I've only won in this building once before. There's something about this building."

"It can be a tough place to play," said defenseman Rick Smith, "but when you come in here, you should automatically be up for the game. It wasn't any problem for us. There were only seven games left and we're in a dogfight."

A week ago, it seemed the Capitals had been bitten by misfortune, with the gravedigger standing ready. But Inness' two brilliant efforts, coupled with tonight's success, give Washington a record in the past four days of beating the NHL's No. 4 team and tying the first and third clubs.

The way this contest started, there was little reason to expect another Capital gain. Palmateer made a great stop on Paul Holmgren's deflection of a Behn Wilson drive in the first minute, but the second Flyer shot went into the net, Rick MacLeish converting Tom Gorence's setup on a two-on-one break.

The next four goals belonged to Washington. Tookey struck from the right-wing circle to tie the score and Gartner rebounded Darren Veitch's drive to send the Capitals ahead to stay. Both goals were on power plays.

The Flyers the encountered further adversity, as what appeared to be a goal by Holmgren was disallowed because linesman Wayne Bonney caught Ken Linesman a couple of inches offside. Moments later, referee Dave Newell penalized two Flyers at the same time, Holmgren for high sticking and Brian Propp for disputing the call, and many in the crowd of 17,077 fans were in an ugly mood.

The Flyers were able to kill those two minutes of five-on-three disadvantage and that figured to reverse the momentum. Instead, there was a more important turnabout.

Palmateer came far out to stop Linseman, on a two-on-one break with Brian Propp, and play quickly moved to the other end as a fine pass by Glen Currie freed Gartner behind Wilson. Gartner deked goalie Pete Peeters and backhanded the puck behind him for a 3-1 lead.

Maruk's 40-footer made it 4-1 early in the third period, then Peeters stopped a Currie breakaway and the Flyers applied tremendous pressure. When MacLeish deflected Terry Murray's drive to make it 4-2, there was still 12:41 left on the clock, and teams have lost two-goal leads here in far less time.

After a penalty to Washington's Jim McGaggart, the Flyers kept the puck in the Washington end for 1:54 without a whistle before Dennis Ververgaert was able to knock it across the blueline. It was the Flyers' last gasp, as Gartner iced the game with a 40-footer that caromed in off the far post with 6:08 left.

"I thought it was going wide," Gartner said, "and I guess the goalie did, too. But it just caught the post and stayed in. It was a great feeling, not because of the hat trick; that doesn't mean anything. The playoffs are the only thing we can think of now. We're not in, but after this it'll take a lot to keep us out."