North Carolina RADAR State Practice Exam

The "28 mph house" incident in Dade County in 1979 is attributed to the unique phenomenon caused by the speed of a defroster fan's blades. In this case, the radar was mistakenly reading the speed generated by the rapidly rotating blades of a defroster fan located in the house.

This incident highlights a crucial aspect of radar technology: that it can sometimes pick up unintended sources of motion. The radar unit misinterpreted the movement of the fan blades as a vehicle traveling at 28 mph, demonstrating how radar systems can be susceptible to interpreting various forms of motion, not just the motion of vehicles on the roadway. The occurrence ultimately serves as a reminder for law enforcement and others who rely on radar technology to verify readings and ensure accurate interpretations of the data being collected.

Understanding this incident provides insight into the limitations and challenges of using radar as a speed measurement tool, emphasizing the importance of correctly identifying the sources of motion that radar units detect.