Two died when a small airplane likely passed too close under an arriving Allegiant jet, causing a loss of control and a fiery crash into a house below. The accident location was approximately 6-miles northwest of the St.Cloud Airport [KSTC]. The one person in the house was not injured when he jumped from the second floor to escape the fire. A news article in the Minneapolis StarTribune reports the small plane was doing a sightseeing flight. The photos show it was a sunny evening with pleasant flying conditions.
Wake Turbulence is one of the greatest hazards in Air Traffic Control. Wikipedia offers a good explanation, including links to some accident histories. Controllers are trained to be attentive to the reality that they may contribute to an accident if they put a small plane into the air vortices that tend to spin off of the wingtips of larger aircraft. These vortices dissipate slowly, and tend to fall to the ground, so controllers know it is much safer to pass the smaller aircraft above the larger one, and NEVER close-in underneath or behind. This short video shows these vortices are like small, horizontal tornados. Awareness of the hazards of wake turbulence began nearly fifty years ago, and coincided with the use of jets. With FAA, rules happen slowly and normally only as a reaction to accidents. Wake Turbulence rules were implemented, but there seems always to be a resistance to impose any more rules than are necessary. Pressures cause the hazards to be diminished and the rule proposals to be pared down. In the long run, though, more accident/incident data shows the folly of these deficient rules, and the rules keep changing every few years, becoming more and more restrictive. This is precisely the rule history FAA has followed on the wake turbulence issue, for nearly fifty years.