On May 12, 2021, at 1023 mountain daylight time, a Cirrus SR22 airplane, N416DJ, and a Swearingen SA226TC airplane, N280KL, were substantially damaged when they collided in flight while approaching to land at Centennial Airport (APA), Englewood, Colorado. The pilot and passenger onboard the Cirrus were not injured, and the pilot onboard the Swearingen was not injured. The Cirrus was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight, and the Swearingen was operated as a Title 14 CFR Part 91 positioning flight. At the time of the accident, parallel runways 17R and 17L were being utilized for simultaneous operations at APA. Automatic Dependent Surveillance-Broadcast (ADS-B) data was provided by the Federal Aviation Administration (FAA), and data from the on-board Remote Data Module (RDM) was downloaded from the Cirrus. The data showed that the Cirrus departed APA for a local flight about 0921, and the Swearingen departed the Salida Airport (ANK), Salida, Colorado, about 0956. About 1022:43, the Swearingen was about 5.5 nm from APA and had completed a right turn to align with the final approach course to runway 17L. At this same time, the Cirrus was on the downwind leg of the right-hand traffic pattern for runway 17R just before commencing a right turn to the base leg of the traffic pattern. The Swearingen continued its approach and remained aligned with runway 17L. The Cirrus continued the right-hand traffic pattern through the base leg, and then began to turn toward the final approach course for the runway. The Cirrus continued through the extended centerline for runway 17R, and then continued to the extended centerline for runway 17L where it collided with the Swearingen. The airplanes collided at 1023:52 when they were about 3.2 nm from APA. The Swearingen was aligned with runway 17L while the Cirrus had not completed the turn from base to final and was heading about 146° when the collision occurred. Figure 1 – Plot of ADS-B and RDM flight path information After the impact, the pilot of the Swearingen declared an emergency, continued to APA, and landed successfully on runway 17L. The pilot of the Cirrus reported that the airplane was not controllable after the impact, and he deployed the Cirrus Airframe Parachute System (CAPS). The Cirrus came to rest about 3 nm north of APA. Both airplanes sustained substantial damage (see figures 2 & 3) Figure 2 – Photograph of the Swearingen after the accident. Figure 3 – Photograph of the Cirrus at the accident scene. Review of the data retrieved from the RDM from the Cirrus revealed that the airplane’s autopilot was disengaged at 1018:50 and stayed off for the remainder of the flight, indicating that the pilot was manually flying the airplane during the landing approach. At 1023:16, the avionics system issued a traffic alert which remained on until the collision. RDM data further indicated that that during the downwind portion of the airplane’s approach, the airspeed was about 125 kts and the flaps were up. Once the airplane was established on the base leg of the traffic pattern the recorded airspeed was about 148 kts and the flaps were still up. As the airplane maneuvered from the base leg to final approach, the airspeed was about 140 kts and the flaps were lowered to 50% about 4 seconds before impact. When the collision occurred, the airplane was about halfway through its turn from base to final at an airspeed of 140 kts, and an altitude of 6,619 ft msl. At 1023:54, the CAPS handle was pulled. According to the Cirrus “Pilot’s Operating Handbook and FAA Approved Airplane Flight Manual” (POH/AFM), the recommended approach speed for the airplane was 90-95 knots indicated airspeed (KIAS) with flaps up, 85-90 KIAS with 50% flaps, and 80-85 KIAS with 100% flaps. Review of communications between both airplanes and the APA Airport Traffic Control Tower (ATCT) revealed that the local control 1 (LC1) controller had cleared the Swearingen for a straight in landing to runway 17L and the local control 2 (LC2) controller had cleared the Cirrus to land on runway 17R. The two controllers communicated with the respective airplanes on different ATCT frequencies. FAA Order JO 7110.65Y detailed air traffic control procedures and phraseology for use by personnel providing air traffic control services. Included in the order were instructions for prioritizing the issuance of traffic alerts when potential conflicts with other aircraft exist. The order also specified conditions in which parallel runway operations could be authorized, including visual flight rules meteorological conditions, and that two-way radio communication be maintained with the aircraft involved and that pertinent traffic information be issued. Further review of the communications at APA revealed that although the LC2 controller had issued pertinent traffic advisories to the pilot of the Cirrus, the LC1 controller did not issue a traffic advisory to the pilot of the Swearingen regarding the location of the Cirrus.