Accident Overview
On July 17, 2018, at 1259 eastern daylight time, a Piper PA-34-200 (N16281) and a Cessna 172N (N6428D) collided in midair approximately 9 miles northwest of Miami Executive Airport (TMB) in Miami, Florida. Both aircraft were destroyed, and all four occupants—the private pilot and designated pilot examiner (DPE) on the Piper, and the flight instructor and student pilot on the Cessna—were fatally injured. Both aircraft were registered to and operated by Dean International, Inc., under 14 Code of Federal Regulations Part 91. The Piper was conducting an evaluation flight for a commercial pilot certificate, and the Cessna was on a cross-country instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed for either flight.
The Piper departed TMB at 1253 for a local flight, while the Cessna departed Immokalee Regional Airport (IMM) at 1217, destined for TMB. According to air traffic control data, the Piper was en route to a training area at about 1,500 ft mean sea level (msl) and was no longer communicating with the TMB tower controller, as it was outside Class D airspace. The Cessna had contacted the tower just before the collision; the controller acknowledged and issued a traffic advisory. Radar data showed the two targets converging nearly straight-on, with the Piper flying northwest and the Cessna southeast at the time of the collision.
Aircraft and Personnel
The Piper PA-34-200 was a six-seat, low-wing, retractable tricycle gear aircraft manufactured in 1973, powered by two Lycoming IO-360 200-horsepower engines with two-blade Hartzell constant-speed propellers. Its most recent annual inspection was completed on June 19, 2018, with the airframe having accumulated about 10,153 total hours. The left engine had 10,207 total hours (1,147 since major overhaul), and the right engine had 11,401 total hours (1,147 since major overhaul).
The Cessna 172N was a four-seat, high-wing, fixed tricycle gear aircraft manufactured in 1979, powered by a Lycoming O-320 160-horsepower engine with a two-blade McCauley fixed-pitch propeller. Its most recent 100-hour inspection was completed on June 13, 2018, with the airframe having 18,447 total hours and the engine 13,256 total hours (2,541 since major overhaul).
The Piper pilot held a private pilot certificate with single-engine land and instrument ratings; her most recent first-class medical was September 29, 2017. She reported 253 total flight hours on her commercial pilot certificate application. The DPE held an airline transport pilot certificate with single-engine land/sea, multiengine land/sea, and glider ratings, as well as a flight instructor certificate. He reported 26,000 total hours at his most recent second-class medical on August 16, 2017. Neither pilot's logbook was recovered.
The Cessna flight instructor held a commercial pilot certificate with single-engine land and instrument ratings, and a flight instructor certificate. He reported 311 total hours on his flight instructor application; his most recent first-class medical was December 15, 2014. His logbook was not recovered. The student pilot held a first-class medical issued March 20, 2018, and had 52 total hours according to his logbook.
Wreckage Examination
The Piper main wreckage came to rest about 620 ft west of the collision point, mostly intact and upright. The vertical stabilizer and outboard right wing were separated. Both engines remained attached; the right propeller was feathered, and cockpit controls for both engines were in the aft position. The right propeller had one blade with little damage and one bent forward; the left propeller had one blade with little damage and one bent aft. The landing gear selector was down, with gear mid-extension; flaps were retracted. Flight control continuity was confirmed, and the stabilator trim jackscrew indicated a nose-up setting midrange between neutral and full nose-up; rudder trim was neutral. Both front seats had lapbelts and shoulder harnesses; the right restraint was unlatched by rescue personnel, and the left was cut.
The Cessna main wreckage was about 1,340 ft southeast of the collision point, upright with its left wing separated. The engine and propeller remained attached; one propeller blade had little damage, while the other was bent aft with chordwise scratches. Flaps were retracted, and flight control continuity was confirmed. The elevator trim jackscrew indicated about 5° trim tab up (nose-down). The right seat restraint was not recovered; the left seat restraint had separated consistent with overload.
Paint transfer (red and blue) was found on the top inboard section of the Cessna's right wing. Tire marks were on the Piper's right wingtip; the Cessna's left main tire was not recovered. Components of the Cessna were found embedded in the Piper: the right upper strut attachment fitting in the tailcone, the left front wing spar carry-through fitting in the outboard right wing, and a section of the right wing spar in the vertical stabilizer. These findings were consistent with a nearly head-on, off-center collision, with the Cessna in a slight left bank relative to the Piper's right.
Meteorological Conditions
The recorded weather at TMB at 1253 included wind from 120° at 5 knots, 10 statute miles visibility, scattered clouds at 3,500 ft and 4,200 ft, temperature 32°C, dew point 24°C, and an altimeter setting of 30.10 inches of mercury.
Medical and Toxicological Findings
Autopsies were performed on all four pilots by the Miami-Dade County Medical Examiner Department. Toxicology testing by the FAA Forensic Sciences Laboratory found no impairing substances in the Piper pilot or DPE (the DPE had ibuprofen, which is not considered impairing). The Cessna student pilot's cavity blood contained ethanol at 0.049 gm/dl, with 0.020 gm/dl in the liver and 0.047 gm/dl in muscle; N-propanol and N-butanol were also present, which can be produced postmortem. The Cessna flight instructor's cavity blood and urine contained 0.0015 µg/mL of delta-9-tetrahydrocannabinol (THC), the psychoactive component of marijuana, along with inactive metabolites. The source notes that marijuana is psychoactive with therapeutic levels as low as 0.001 µg/mL, but establishing a relationship between concentration and impairment is difficult.
Performance and Visibility Study
A study using ADS-B and TIS-B data analyzed aircraft positions and cockpit visibility. Neither aircraft was equipped with a cockpit display of traffic information (CDTI). The study found that the two airplanes would have appeared as small, slow-moving objects until about 12 seconds before the collision. About 18.5 seconds before impact, the Cessna would have been obscured from the Piper pilot's field of view by the instrument panel, but would have remained visible to the DPE. A simulation of CDTI indicated that both pilots could have been alerted to the other aircraft as early as 6 minutes and 10 seconds before the collision (when the Piper became airborne), but the presence of numerous traffic targets near TMB would have given little reason for particular attention until closer. About 39.5 seconds before the collision, each aircraft would have received an aural and visual ADS-B Traffic Advisory System (ATAS) alert; the Cessna would have received a second alert 30.5 seconds before impact. On a CDTI, alert status (solid yellow arrowheads in a yellow circle) would have been displayed until the collision.