Accident Sequence
The ARTCC asked the pilot of Airspur 8773 if he could execute the VOR instrument approach. The pilot stated he could, but wanted to "hold for a while to see if [the weather] gets a little better." According to the METAR, visibility was 1.75 statute miles with a 200-foot overcast ceiling. He was cleared to hold north of the VOR at 12,000 feet msl. During holding, the pilot filed a PIREP indicating light rime icing. Shortly thereafter, he was cleared for the approach.
Three witnesses observed the airplane on the downwind leg, just past midfield, at an estimated altitude of 500 feet. One witness then heard the engine "spool up to high power...[like reversing] the pitch of the propeller to slow down," and thought the airplane had landed. Five witnesses reported the airplane emerged from the overcast and banked "sharply to the left, then back to the right, then back to the left, then took a hard bank to the right," rolled inverted, and struck the highway just south of the airport perimeter. The airplane slid down an embankment and out into a lake, becoming partially submerged. Witnesses noted it was "snowing hard" and the highway was covered with 1 to 2 inches of slush.
Wreckage and Toxicology
Wreckage examination revealed the flaps were down 30 degrees, the wing deice boots were "ribbed," and the inertial separator was open. The toxicological report detected chlorpheniramine, desmethylsertraline, sertraline, and pseudoephedrine in blood. Urine contained chlorpheniramine, sertraline, phenylpropanolamine, pseudoephedrine, and acetaminophen. Sertraline (Zoloft) is a prescription antidepressant; according to the Guide for Aviation Medical Examiners, "The use of a psychotropic medication is considered disqualifying. This includes all... antidepressant drugs..." Chlorpheniramine is an over-the-counter sedating antihistamine used for allergies. Pseudoephedrine (Sudafed) is a decongestant. Acetaminophen (Tylenol) is a pain reliever. Dr. Stanley R. Mohler's "Medication and Flying: A Pilot's Guide" notes side effects of chlorpheniramine include drowsiness, dizziness, and lessened coordination; pseudoephedrine side effects may include sleepiness, dizziness, restlessness, headache, and possible loss of coordination, alertness, or confusion.
Probable Cause
The official probable cause was the pilot's failure to maintain aircraft control. Contributing factors included the pilot's failure to divert to an alternate airport, an inadvertent stall, and the snow and icing conditions.