PHOENIX (AP) -- The Arizona Department of Public Safety says it'll have an eye in the sky for traffic enforcement on a heavily traveled highway in northwest Arizona over the Presidents Day weekend. The DPS say the crew of a single-engine plane will be looking for vehicles that are speeding or engaging in other dangerous driving behavior on U.S. 93. U.S. 93 is part of the main highway route between Phoenix and Las Vegas, and the DPS says its previous airborne traffic enforcement operations found that the average speed on the highway was 86 mph. According to DPS, the airplane's pilot and observer contact Highway Patrol units on the ground to arrange traffic stops. The operation is focused on U.S. 93 south of Interstate 40.