On April 11, 2026, about 1330 eastern daylight time, a Cessna 172S airplane, N529ND sustained substantial damage and a Raytheon Aircraft Company B200 (King Air) airplane, N699BW sustained minor damage when they collided in flight near Marathon, Florida. The 2 pilots aboard the Cessna and the 2 pilots and 4 passengers aboard the King Air were not injured. The Cessna was being operated as a Title 14 Code of Federal Regulations (CFR) Part 91 instructional flight, and the King Air was being operated as Title 14 CFR Part 91 business flight. Preliminary air traffic control communications and ADS-B data provided by the FAA showed that the King Air departed Marsh Harbour (MHH), Bahamas to the southwest inbound to the Florida Keys Marathon International Airport (MTH), Marathon, Florida. About 20 nautical miles northeast of MTH, the pilot requested to cancel their instrument flight rules (IFR) flight plan to MTH. The IFR cancellation was received, and a frequency change was approved. Air traffic control informed the King Air pilots that there was traffic flying in the opposite direction at 15 miles and 5,500 ft “following the keychain.” The King Air pilots subsequently reset their transponder code from a discrete code to 1200 (the standard transponder code used by airplanes operating under visual flight rules [VFR]) as they were descending out of about 11,000 ft mean sea level (msl). The Cessna pilots reported that they were northeast bound at 5,500 ft msl, about 10 miles northwest of MTH, operating VFR with flight following. Air traffic control notified them of unknown traffic ahead at 12 o’clock and 1 mile descending out of 6,200 ft msl. Immediately after the traffic advisory, the Cessna pilot reported that “we had a midair collision,” declared an emergency, and returned to MTH for landing. The Cessna pilots stated that they had briefly observed the King Air immediately before the collision but were unable to take evasive action. The pilot advised the controller of left wing damage and control difficulties and requested emergency services upon landing. The pilot in command (PIC) of the King Air reported he was looking out the window, scanning for the traffic, when he observed the Cessna immediately before impact. He attempted evasive action; however, the left engine, wing and propeller impacted the left wing of the Cessna, which resulted in substantial damage to the Cessna’s wing and aileron. The outboard 36 inches of the Cessna’s left wing was sheared off and crumpled, with the aileron remaining partially attached, and bent aft. The King Air sustained minor damage to the left propeller, engine intake and the leading edge of the left wing. Both airplanes landed safely at MTH and were retained for further examination following the collision.