On September 23, 2017, about 1702 eastern daylight time, a Piper PA-28R-201 airplane, N1881H, and a Robinson R22 helicopter, N404TB, were substantially damaged when they collided in mid-air over the runway at Clearwater Air Park (CLW), Clearwater, Florida. The private pilot aboard the airplane received minor injuries, and the flight instructor and a pilot receiving instruction aboard the helicopter also received minor injuries. Both aircraft were owned and operated by Tampa Bay Aviation. Visual meteorological conditions prevailed at the time of the accident. Both flights were operated under Title 14 Code of Federal Regulations Part 91, and no flight plans had been filed. N404TB was an instructional flight that departed CLW at 1630 and N1881H was a personal flight that departed CLW at 1600.According to the flight instructor, the purpose of the flight was a flight review of the pilot receiving instruction. He indicated that he never flew with the pilot receiving instruction prior to the accident and both of them were wearing headsets. The pilot receiving instruction proceeded to the hover practice area and executed multiple practice maneuvers. All radio calls were made during every turn while in the airport traffic pattern. The instructor performed all radio calls at each leg of the airport traffic pattern during the first approach; while the pilot receiving instruction made the radio calls at each leg of the airport traffic pattern during the second takeoff and approach to the runway. In addition, prior to every turn, they scanned in all directions for traffic. While on a final approach, the instructor noticed a fixed-wing airplane on the base leg of the airport traffic pattern for runway 16, and he announced on the common traffic advisory frequency (CTAF) that they were using runway 34. They heard the pilot of the fixed-wing airplane say something unintelligible and observed the airplane veer away, flying to the west. The instructor then allowed the pilot receiving instruction to continue the approach to runway 34, which terminated with a hover, touchdown, and liftoff. The flight returned to the airport traffic pattern for runway 34. When the flight was 1 mile from the runway, the pilot receiving instruction turned onto final approach for runway 34 and executed a steep approach. The instructor told the pilot receiving instruction to extend the flight path to the segmented circle. The helicopter came to a hover over runway 34 about 15 ft, when he heard a loud sound, and felt the helicopter being pushed forward. The helicopter then began to spin and impacted the ground hard and came to rest upright. According to the pilot of the airplane, he was operating on the CLW common traffic advisory frequency and stated that between his first and second radio transmission he heard a heavy buzzing sound like a helicopter rotor with the words "34" barely distinguishable. The pilot scanned for air traffic and declared being on downwind via his radio. The pilot quickly turned to the base leg of the traffic pattern and decreased the engine power to descend. About that time, he quickly scanned of the airport environment, focusing on the taxiway to runway 34, the line of trees ahead, as well as the end of the runway and saw nothing unusual. He was confident his calls on the radio were heard. The pilot proceeded to land; about 2 seconds prior to the impact he saw the helicopter hovering "immobile," about 10 ft above the runway. He recalled the tail was pointed towards the airplane and absolutely stationary. The pilot tried to avoid the helicopter, then heard a loud sound followed by the airplane inverting and sliding on its canopy. After the airplane came to a stop the pilot exited the airplane. According to another pilot/witness that was approaching CLW, about 2 miles west of the airport, he heard the radio call from the helicopter when it was on a 1-mile final at 500 ft. He flew over CLW and saw the accident outcome. He indicated that he was monitoring the CLW CTAF and did not hear the pilot of the airplane announce his intentions. Due to the accident the witness diverted to another local airport. A Federal Aviation Administration inspector examined both aircraft at the accident site and discovered that both the helicopter and airplane sustained substantial damage. The airplane sustained damage to the fuselage and the left wing separated from the airframe. The helicopter's tubed airframe was buckled. Examination of the radio communication system in the airplane and helicopter did not reveal any anomalies. A review of a surveillance video showed the helicopter descending and slowing to stationary hover over the runway 34 threshold. Just as the helicopter had slowed to a hover, the airplane entered the frame of the video from the left, about 2 seconds before the collision. At that point the airplane's main landing gear appeared to be on, or just above the ground, and it then entered a slight climb as it continued down the runway. At this point the helicopter was oriented with its nose facing down the runway, while the airplane was approaching the helicopter from behind. Over the next 2 seconds, the airplane climb to roughly the height of the hovering helicopter before the airplane's left wing struck the aft side of the helicopter. The helicopter yawed to the left and descended to the ground, while the airplane rolled left and impacted the ground in an inverted attitude. See-and-Avoid Concept According to 14 CFR 91.113, "Right-of-Way Rules," "when weather conditions permit, regardless of whether an operation is conducted under instrument flight rules or visual flight rules, vigilance shall be maintained by each person operating an aircraft so as to see and avoid other aircraft." In addition, FAA AC 90-48D, "Pilots' Role in Collision Avoidance," which was in effect at the time of the accident, stated that the see-and-avoid concept requires vigilance at all times by each pilot, regardless of whether the flight is conducted under instrument flight rules or VFR.