At 2306 Pacific time, the airplane collided with mountainous terrain while executing an approach to the Van Nuys (Calif.) Airport. The Private pilot was the sole occupant and was fatally injured; the airplane was destroyed. Instrument conditions prevailed, but no flight plan had been filed for the flight that originated in Santa Ana, Calif. After receiving a pop-up IFR clearance for the ILS approach to Runway 16R at Van Nuys, the airplane made a sudden diversion to the right, off the localizer course. He was then directed to climb to 5000 feet on a southerly heading. The pilot acknowledged the instructions, stating he had a problem and was climbing. The pilot made no further transmissions before radar contact was lost.