Seven Harvard mountain climbers, who for four days had been feared lost on the treacherous northern slopes of Alaska's Mt. McKinley, were spotted Sunday night by a rescue plane and appear to be safe and continuing their climb.

When sighted by veteran bush pilot Don Sheldon, the seven were at 17,000 feet. The last time they had been seen was a week ago, when they scaled 2000 feet of the previously unconquered east side of Mt. McKinley's Wickersham Wall. Observers had expressed apprehension that the party had been buried in one of a series of avalanches that swept Wickersham Wall recently, but the climbers are now above the avalanche region and are apparently out of danger.

The climbers, all members of the Harvard Mountaineering Club, were led by club president Henry L. Abrons '63, of Dunster House and Scarsdale, N.Y.. The others were: Edward C. Carman '63, of Dunster House and Nashville, Tenn.; Christopher Goetze '61, of Randolph, N.H.; John A. Graham '64, of Lowell House and Tacoma, Wash.; Richard G.C. Millikan '63, of Leverett House and Berkeley, Cal.; David S. Roberts '65, of Dunster House and Boulder, Colo.; and Donald C. Jensen '65, of Dunster House and Walnut Creek, Cal.

Sheldon found the party on his third sortie, after the first two had been thwarted by heavily overcast weather. Another plane, piloted by Lowell Thomas Jr., son of the commentator, had also been searching for the mountaineers.

The Mountaineering Club is attempting an extremely difficult ascent of the 19,420-foot North Peak of Mt. McKinley. The climb involves scaling Wickersham Wall, a sheer precipice of rock which rises some 14,000 feet. A group of Canadians climbed the wall last month, but the eastern route of the Harvard climbers is considerably more challenging than the route taken by the Canadian party.

Accomplished Climbers

Every member of the Harvard group is an accomplished mountain climber. Abrons has previously climbed Mt. McKinley by another approach.

Since the climbers are carrying no radio transmitter or receiver, the only way they can be located is by being sighted from a plane. It is probable that the party has already reached the North Peak and is beginning its descent.