On February 11, 1997, about 1520 hours Pacific standard time, a Piper PA-28-161, N8436X, is presumed to have crashed into the Pacific Ocean while on a whale watching excursion. The pilot is presumed to have been fatally injured. Visual meteorological conditions prevailed for the personal flight and no flight plan was filed. When the aircraft failed to return to the home base by 1500, a concerned party notified authorities. After determining that the aircraft had landed at Catalina Airport, Avalon, California, radar data was obtained. The approximate departure time was obtained from the unicom radio operator at Avalon. A transponder code of 1200 was tracked after departure from Avalon. The last recorded radar contact was at 1519:19 in the area of the Oceanside VOR on the 263 degree radial about 24.8 miles. A search of the area between Avalon and the coastline by the U.S. Coast Guard had negative results.