Primary finding
Probable cause
The pilot-in-command’s inadequate preflight planning for the high density altitude and relative humidity conditions and his failure to recognize the need to reject the takeoff, allowing the student pilot to execute an abnormally long takeoff roll and apply excessive nose-high control inputs, which resulted in rotation with inadequate climb performance and an inflight collision with terrain.
Investigator assessment
Analysis narrative
The private pilot, who was pilot-in-command (PIC) and seated in the left seat, and the student pilot, who owned the airplane and was seated in the right seat, had landed at the airport with the two passengers to refuel the airplane. The airport had a field elevation of 5,045 ft mean sea level (msl) and the density altitude was calculated to be 6,375 ft. The PIC calculated that the airplane’s weight after fueling was about 38 lbs under its maximum gross weight and within the center of gravity envelope. The student pilot taxied the airplane for departure and reported that the engine run-up was normal. He subsequently requested a “short delay” from the air traffic controller to review the takeoff checklist with the PIC, including verifying the flap setting, rotation airspeed, and climb airspeed. During the takeoff roll, the airplane used about 3,000 ft of runway before rotating. When the airplane was about 200 ft above ground level (agl), it stopped climbing, and the stall warning light illuminated. The student pilot said he had “every intent of us pulling on the yoke to maintain the climb” but that, after a few seconds of trying to gain airspeed by leveling the nose, the airplane would not maintain airspeed or gain altitude. The PIC took control of the airplane to attempt to maximize airspeed and glide distance but stated that his forward visibility was limited due to the airplane’s nose-high attitude and that he was unable to see a nearby road that the student pilot had identified as suitable for landing; the student pilot took control of the airplane and directed it toward the road. During the landing sequence, the airplane collided with treetops and a tree branch before coming to rest at the side of the road. Postaccident examination of the airplane and engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. Using an external fuel source, the engine was run uneventfully throughout various power settings. According to the airplane performance charts in the owner’s handbook (OH) for the airplane, based on the density altitude conditions at the time of takeoff, the calculated takeoff distance ground run for the airplane was about 1,600 ft. Although the student pilot had mistakenly calculated that the ground run would be “around 2,700 ft,” the student pilot continued the takeoff after the airplane’s ground roll exceeded that distance, and the PIC did not call for a rejected takeoff. The 7,619-ft runway would have provided ample distance to stop the airplane on the runway had a rejected takeoff been initiated, even at the erroneously calculated ground roll distance. The excessive ground roll before rotation, the illumination of the stall warning light shortly after rotation, and the student pilot’s statement that his intention was to pull on the yoke to maintain the climb all provide evidence that the student pilot excessively raised the airplane’s nose during the takeoff roll and climb; the PIC did not intervene until after the stall warning light illuminated. The excessive nose-high attitude degraded the airplane’s takeoff roll and climb performance. Further, the PIC stated that the student pilot reported a loss of engine rpm during the climb. The pretakeoff engine run-up (ground check) procedures in the OH for the airplane specified the use of carburetor heat to melt any ice that may have formed during taxiing. However, as noted earlier, after completing the run-up, the PIC and the student pilot delayed initiating the takeoff roll. Given this extended ground time after run-up, and based on the carburetor icing probability charts that indicated the conditions were conducive to the formation of serious carburetor icing at glide power, it is possible that carburetor icing formed, further degrading the airplane’s takeoff and climb performance.
Source record
Factual narrative
On September 2, 2023, about 0806 mountain standard time, a Piper PA-28-140, N6834W, was substantially damaged when it was involved in an accident near Prescott, Arizona. The private pilot, student pilot, and two passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. The private pilot, who was pilot-in-command (PIC), and the student pilot, who owned the airplane, both reported that they had flown the airplane with the two passengers earlier that morning from Falcon Field Airport (FFZ), Mesa, Arizona, to Prescott Regional/Ernest A Love Field Airport (PRC), Prescott, Arizona. The private pilot, who was seated in the left seat, stated that he flew the airplane until the flight approached PRC, at which time the student pilot, who was seated in the right seat, took the controls for the approach and landing. Both the private pilot and the student pilot reported that the flight from FFZ to PRC was uneventful. The student pilot stated that while at PRC, the airplane was partially refueled, and he verified that the tanks were filled only to the tabs, as requested. The private pilot estimated that they were on the ground for about 20 minutes before boarding for departure. According to the private pilot’s calculations, the airplane’s ramp weight was about 2,112 lbs (38 lbs under the maximum gross weight) and within the center of gravity envelope. The student pilot stated that “our calculated rollout” for the airplane’s weight, density altitude, and planned short-field takeoff configuration “was around 2,700 ft.” According to the private pilot, the student pilot assumed control of the airplane for the departure, taxied the airplane to runway 21L, and performed the run-up checklist uneventfully. The student pilot reported that, while conducting the “run-up checklist and leaning checklist…all instruments were on the green.” Both the private pilot and the student pilot reported requesting a “short delay” from the air traffic controller before takeoff; according to the student pilot, he used that time to review the short-field takeoff checklist with the private pilot, including verifying the flap setting, rotation airspeed, and climb airspeed. The student pilot stated that he set the flaps at 25° and planned for a rotation speed of “55 knots” (about 64 mph) and a climb speed of “64 knots” (about 74 mph). The student pilot stated that he taxied the airplane onto runway 21L, applied brake pressure, advanced the throttle to full power, checked the instruments, then released the brakes. He stated that the airplane “went airborne” about 3,000 ft down the runway, and that, for the first few seconds, “everything look[ed] and sounded perfectly normal.” He stated that, once the airplane ascended to about 200 ft agl, it “stopped climbing.” Around the same time, he noticed the stall warning light illuminate with “every intent of us on pulling on the yoke to maintain the rate of climb.” The private pilot stated that he observed that the airplane “was not achieving the expected rate of ascent” and that the student pilot “subsequently reported a drop in rpm.” The student pilot stated that, “after a few seconds…trying to gain airspeed by leveling the nose,” he noted that the airplane was not able to maintain altitude or airspeed, and he realized that they needed to conduct an emergency landing. The private pilot stated that he took control of the airplane to attempt to maximize airspeed and pitch for glide distance while the student pilot notified the air traffic controller that they were going down. The student pilot stated that the private pilot performed the “power off” landing from memory because there was no time to retrieve the checklist. The private pilot stated that, “due to the elevated nose attitude,” his forward visibility was limited, but the student pilot saw a road off the right side of the airplane. The student pilot stated that he took the controls and descended the airplane toward the road. The private pilot stated that, as the airplane descended, “the loss of power was accompanied by a pronounced noise and vibration” from the airplane and that, shortly thereafter, the airplane’s left wingtip made contact with a tree. The student pilot stated that the airplane struck “the top of trees on our path, and, right after, a tree branch to the left of the airplane made contact with the left wing.” Both the private pilot and the student pilot reported that the airplane then spun around; the student pilot estimated that it turned about 270° before it came to rest upright next to the road on which they were trying to land. All occupants exited the airplane, and first responders arrived within minutes. Photographs from the accident site showed the airplane resting on its nose on the side of a road with the nose landing gear displaced upward and to the left against the bottom of the fuselage. The fuselage was buckled at the firewall, the empennage was buckled aft of the cabin and displaced to the left, and the left wing showed leading edge crush damage near the tip. The flaps were in an extended position. Small branches and leafy tree or shrub material were at the top front of the engine cowling behind one propeller blade, which showed some chordwise scratching and paint loss on the leading edge near the blade tip. The other propeller blade was bent aft about midspan and underneath the nose of the airplane in contact with the road. POSTACCIDENT EXAMINATION A postaccident examination of the airframe revealed continuity throughout the fuel system. The fuel selector valve appeared undamaged and rotated normally, and each detent was noticeable. Throttle and mixture control cable continuity was established from the cockpit controls to the carburetor, and all levers moved freely from stop to stop when actuated by hand. An external fuel source was attached to the engine and the engine was started. The engine throttle was advanced to about 1700 rpm. The engine ran throughout various power settings uneventfully for about 5 minutes. A functional check was conducted of the magnetos with a change of about 75 rpm between magnetos. The throttle was advanced to the full forward position, and a static rpm of about 2700 was observed. The engine ran smoothly during the operational check and exhibited no unusual indications before it was shut down using the mixture control. AIRPLANE PERFORMANCE INFORMATION The OH for the airplane specified a maximum gross weight of 2,150 lbs. Section IV, Performance Charts, provided performance charts for Take-off Distance vs. Density Altitude and Rate of Climb vs. Density Altitude. Based upon a calculated density altitude of 6,357 ft (see “Meteorological Information” below), the calculated takeoff distance ground run for the airplane at maximum gross weight was about 1,700 ft, with a distance of about 3,500 ft to clear a 50 ft obstacle. The calculated rate of climb was about 400 ft per minute at maximum gross weight. Section III of the OH specified that the takeoff technique involves “allow[ing] the airplane to accelerate,” then easing “back on the wheel enough to let the airplane fly itself off the ground. Premature raising of the nose, or raising it to an excessive angle, will result in a delayed takeoff. After takeoff, let the aircraft accelerate to the desired climb speed by lowering the nose slightly.” The Short Field, Obstacle Clearance takeoff procedures in the OH specified lowering the flaps to 25°, accelerating to 55-60 mph (about 48 to 52 kts) to begin rotation, and, after breaking ground, accelerating to the best angle of climb speed of 74 mph (about 64 kts). The procedure stated, “slowly retract the flaps when the obstacle has been cleared and continue to climb at 85 mph” (about 74 kts). The Short Field, No Obstacle takeoff pr