NTSB Final Report: Chandler, AZ

Flight Conducted Under:  Part 91: General aviation - Instructional (A1); Part 91: General aviation - Instructional (A2)

Analysis

A low-wing airplane and a helicopter, both of which were operating as instructional flights with flight instructors onboard, were performing takeoffs and landings at the tower-controlled airport in day visual meteorological conditions. The helicopter was performing right traffic patterns to the taxiway that paralleled the runway, while the airplane was performing right traffic patterns, outside of and above the helicopter pattern, to the runway. The helicopter had been cleared for “the option” to the taxiway, while the airplane was cleared to land shortly thereafter.

After receiving landing clearance, the instructor onboard the airplane elected to conduct a simulated engine failure to a full-stop landing, reducing the engine power to idle abeam the approach end of the runway, but did not advise the tower controller of his intentions. While on final approach, the instructor took control of the airplane and entered a forward slip. The instructor and student then heard and felt a loud “bang” and the instructor declared an emergency, thinking that the airplane had impacted birds.

Flight track information, witness statements, and damage to the airplane indicated that the airplane descended into the helicopter while both aircraft were on final approach for landing. Review of tower control communications indicated that the accident airplane had been advised and was aware of helicopters operating to the parallel taxiway. The tower controller cleared the airplane to land behind a twin-engine airplane, and advised of a helicopter low and to the airplane's right (the accident helicopter). The circumstances of the accident are consistent with the failure of the pilots onboard the airplane to see and avoid the helicopter during landing approach, resulting in a collision with the helicopter. It is possible that the airplane’s low-wing configuration and steep descent while in the forward slip may have contributed to the pilots’ failure to see the helicopter below them.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be: The failure of the pilots onboard the airplane to see and avoid the helicopter while maneuvering in the traffic pattern, which resulted in a midair collision.

Findings

History of Flight

On October 1, 2021, about 0740 mountain standard time, a Piper PA-28-181 airplane, N2868H, and a Robinson Helicopter Company R22 helicopter, N412TL, were involved in a midair collision near Chandler, Arizona. The airplane sustained minor damage and the flight instructor and student pilot onboard were not injured. The flight instructor and student pilot onboard the helicopter were fatally injured, and the helicopter was destroyed. Both aircraft were operated as Title 14 Code of Federal Regulations Part 91 instructional flights.

The flight instructor and student on board the airplane requested and received clearance from the tower controller to perform takeoffs and landings from runway 4L, remaining in the airport traffic pattern. After completing three touch-and-go landings, the tower controller instructed the airplane to switch to runway 4R and issued a frequency change. The instructor and student continued to perform touch-and-go takeoffs and landings from runway 4R, and the instructor recalled the controller requesting that the airplane extend their crosswind leg for helicopter traffic during one of their patterns.

During the accident approach, the airplane was cleared for landing behind a twin-engine airplane. The instructor stated that he scanned the area for traffic, and abeam the runway numbers on the downwind leg of the traffic pattern, reduced engine power to idle to simulate a loss of engine power. On final approach for landing, the instructor took control of the airplane to demonstrate a slip and they heard and felt a loud bang. The instructor declared an emergency, thinking that the airplane had hit birds. During the landing flare, the flight instructor noticed the left wing continued to descend and used aileron inputs to keep the wing up. After the airplane touched down, it veered left and exited the runway before it came to a stop between runway 04R and 04L. Once the airplane came to a stop, he and the student pilot exited the airplane.

Witnesses reported that an airplane on final approach descended on top of a helicopter and impacted the helicopter’s main rotor blades. The helicopter descended, impacted terrain, and a post-impact fire ensued.

Review of air traffic control communications revealed that, about 0732, the accident airplane was advised to extend the upwind leg for helicopters operating in the parallel taxiway pattern; one of the pilots acknowledged. About 737:06, the accident helicopter was cleared to land on the taxiway. At 0737:52, the controller cleared the airplane to land behind the twin-engine airplane, and also stated that a helicopter was present at low level, ahead of the airplane to the right, proceeding southbound. The accident airplane acknowledged. At 0740:41, the instructor onboard the airplane declared an emergency following the collision.

Recorded Automatic Dependent Surveillance-Broadcast (ADS-B) data provided by the Federal Aviation Administration (FAA) showed that both aircraft appeared to be on a base to final turn, with the airplane on the approach to runway 04R and the helicopter on the approach to taxiway C (parallel to and to the right of runway 04R). The data showed that the flight paths of the aircraft intersected about 0740:15 at an altitude of about 1,400 ft mean sea level (msl), as seen in Figure 1.

Figure 1. View of helicopter and airplane ADS-B flight track data

Student pilot Information (A1)

Flight instructor Information (A2)

Student pilot Information (A2)

At the time of the accident, the airplane flight instructor had accumulated about 425 total hours of flight experience, of which 32 hours were as a flight instructor.

Aircraft and Owner/Operator Information (A1)

Meteorological Information and Flight Plan

The Chandler Municipal Airport (CHD) FAA contract tower (FCT) had a Letter of Agreement (LOA), dated August 2020, with the helicopter operator that specified responsibilities, defined terms, and established the procedures for operations of helicopters within the CHD class D airspace. The provision of the letter applied only to helicopters conducting operations by persons authorized by the helicopter operator and only when CHD control tower was in operation. The LOA established a helicopter traffic pattern to taxiway C. (see Figure 2.) The helicopter traffic pattern altitude was 1,900 ft msl and the fixed wing traffic pattern altitude was 2,300 ft msl.

Figure 2. View of helicopter and airplane traffic pattern

Wreckage and Impact Information (A2)

Examination of the airplane accident site revealed that the airplane came to rest upright on the dirt field between runways 04R and 04L, on a heading of about 345° magnetic. The helicopter impacted terrain about .5 mile southwest of the approach end of runway 04R.

Postaccident examination of the airplane did not reveal evidence of any mechanical anomalies that would have precluded normal operation. Flight control continuity was established from the cockpit to all primary flight controls. The airplane’s nose landing gear and tire, as well as the left main landing gear, had separated from the airplane and were located near the helicopter wreckage. Both tires were cut consistent with contact from the helicopter’s main rotor blades. A piece of the helicopter’s canopy was found lodged in the hat channel on the underside of the airplane.

The helicopter came to rest on its left side on a heading of about 053° magnetic, at an elevation of 1,236 ft msl. No visible ground scars were observed surrounding the wreckage. All major structural components of the helicopter were located within about 15 ft of the main wreckage.

Postaccident examination of the helicopter was limited due to impact damage and post-crash fire.

The helicopter flight instructor toxicology testing performed at the FAA Forensic Sciences Laboratory found no drugs of abuse.

The helicopter student pilot’s toxicology testing performed by the FAA Forensic Sciences Laboratory detected amphetamine at 7 ng/ml in the student pilot’s urine.

Amphetamine is a Schedule II controlled substance that stimulates the central nervous system. It is available by prescription for the treatment of attention deficit disorder and narcolepsy. It carries a boxed warning about its potential for abuse and has warnings about an increased risk of sudden death and the potential for mental health and behavioral changes. In some preparations, the prescription drug is metabolized to amphetamine; commonly marketed names include Adderall, Dexedrine, and Vyvanse. After a single 30 mg oral dose, early blood levels averaged 0.111 ug/ml and average blood levels in adults using the long-acting prescription orally for a week were about 0.065 ug/ml.

Administrative Information