Final report is out. I don’t have a link.
*** Final Report ***
N23UB MIG-23UB Belleville Michigan 13 AUG 2023
2 POB - Serious Injuries
Pilot Flight Time:
PIC - 21296 hours (Total, all aircraft), 42 hours (Total, this make and model)
Pilot Rated Observer - 15000 hours (Total, all aircraft), 12 hours (Total, this make and model)
On August 13, 2023, about 1610 eastern daylight time, a Mikoyan Gurevich MiG-23UB airplane, N23UB, was destroyed when it was involved in an accident near Belleville, Michigan. The pilot in-command (PIC) and pilot-rated observer (PRO) received serious injuries.
The flight was performing at the Thunder Over Michigan Air Show held at the Willow Run Airport (YIP), Ypsilanti, Michigan. The accident flight was scheduled to be the second to last act. The airplane was a privately-owned, Russian-designed military fighter that employed variable geometry wings that allowed the wing sweep angle to be changed in flight. The airplane was powered by a single turbojet engine with an afterburner. The PIC was seated in the front cockpit and the PRO was seated in the rear cockpit.
The PIC reported that the flight departed from runway 23 at YIP, first using maximum power, followed by minimum afterburner, and then maximum afterburner. He then deselected afterburner as he turned the airplane onto the downwind leg of the traffic pattern. The PIC noted nothing unusual at this time.
The PIC then maneuvered the airplane for a “banana pass” (a low-level, knife-edge display pass) along runway 23. As the airplane approached for the display pass, the PRO swept the wings to the 45° position, at which time the PIC glanced at his airspeed indicator and noticed the airplane was slower than he thought it should have been, but it was still above the minimum maneuvering speed. The PIC believed this may have been the first indication that the engine was losing power, but he did not realize it at this time. To increase airspeed, he advanced the throttle and decreased pitch slightly.
About this time, the PRO announced that it was time to engage the afterburner for the display pass. The PIC advanced the throttle to the full position and pulled the afterburner paddle switch to engage the afterburner, but there was no increase in engine power. He announced to the PRO that the afterburner did not engage and that he was attempting it again. He pulled the throttle back to midrange and then readvanced it, using the same procedure to engage the afterburner, but there was still no increase in engine power.
The PIC and the PRO confirmed with each other that an emergency existed. The PIC visually located YIP and decided that he needed to continue toward the airport. About this time, the PRO announced that he had selected the wings to the 16° sweep position, which the PIC acknowledged. The PIC maneuvered the airplane back toward YIP using the angle-of-attack indicator to keep the airplane from entering an aerodynamic stall. He stated that his intention was to place the airplane into an area away from the public, at just above stall speed.
The PIC located an area that met these criteria and was maneuvering the airplane toward that location. He also noted that the engine was running above idle and was still producing some thrust, but not enough to maintain airspeed and altitude. The PIC believed that the airplane would have been able to descend to a large field, just past a large highway but short of the runway. About this time, the PRO stated that flap deployment was needed, which the PIC delayed to maintain a better glide ratio. He believed he later selected the takeoff flap position when the airplane was about 190 kts, which was the lowest airspeed he remembered. The PIC stated that the flight controls were operating during the entire flight and that the airplane never approached an aerodynamic stall.
The PIC stated that once the airplane was established in the glide to the selected landing area, he then had time to attempt to diagnose the loss of engine power. He first activated the emergency nozzle control but did not feel any immediate response from the engine. About that time, that the PRO stated, “We need to get out of the jet,” to which the PIC responded, “No.” The PIC stated he was surprised by the PRO’s statement, as he had not considered ejecting and did not thereafter. After attempting to reestablish engine power using the emergency nozzle control, the PIC intended to use the emergency engine control, which bypasses the automatic fuel control, to reestablish engine power; however, he did not remember if he was able to activate the switch before the ejection seat fired and he departed the cockpit.
The PRO stated that while the airplane was descending and accelerating for a display pass, he swept the wings back to 45°. As they approached the air show line and the PIC moved the throttle forward into the afterburner range, the thrust from the engine dropped to near zero and the airplane began to decelerate. The PRO stated that the deceleration was such that he was pulled forward against his shoulder straps. The descent reached 500 ft agl, and the PIC began a climbing left turn. The PIC said that they had a problem, and the PRO agreed.
The PIC moved the throttle to idle, then forward to the maximum without afterburner, and then into the afterburner range. The PRO stated that there was no change in engine rpm, no restoration of thrust, and no change in engine noise. The PRO stated that the PIC attempted this throttle movement at least three more times. As the airplane climbed, the airspeed decayed, and the PRO stated that he made airspeed callouts as the airplane slowed. The PRO told the pilot, “We need the wings to 16°,” and the PIC agreed. The PRO selected the 16° wing position, and the wings moved to that position. The PRO said that the airspeed decreased below 200 kts and he declared an emergency over the air show communication frequency.
The PRO said they briefly discussed the engine power loss, and the PIC asked if they could make it to runway 27, to which the PRO replied, “No.” He said that the altitude peaked at 900 ft agl, and the PIC then began trading altitude to maintain airspeed. He said the airplane was in and out of the stall buffet, and he asked the PIC if they needed flaps. He stated that the PIC said, “Yes,” the PIC selected takeoff flaps, and the PRO confirmed the flap and slat deployment. The PRO stated that the airplane was in a descending left turn and the trajectory would intersect terrain outside the airport perimeter and over 2 miles south of runway 27 at YIP. He stated that he communicated the need to eject with the PIC. After several seconds without a response, as the airplane was descending below 350 ft agl, the PRO activated the ejection sequence and both occupants were ejected from the airplane.
Video evidence indicated that the airplane was in a left bank when the ejection seats fired. The airplane continued in the left bank and descended into the ground about 1.7 miles south of the approach end of runway 27 at YIP. The wreckage path was about 600 ft long on a heading of about 35°. There was a postimpact explosion and fire. The fuselage section that contained the tail surfaces and engine came to rest adjacent to an apartment building. The remainder of the airplane was fragmented and distributed along the wreckage path. Both occupants landed in a lake and received serious injuries. There were no reported injuries on the ground.
The PIC, who was the owner of the airplane, held an airline transport pilot certificate with type ratings for Airbus 320, Boeing 757, Boing 767, Boeing 777, Aero Vodochody L-39, and MiG 23 airplanes. He reported having a total of 21,296 hours of total flight experience, including 42 hours in MiG 23 airplanes. In addition to his civilian flight experience, the pilot previously served as a United States Naval Aviator. During his military career, he accumulated 2,500 hours flight experience, including 47 combat missions, and 250 aircraft carrier landings.
The rear-seat PRO held an airline transport pilot certificate with type ratings for Boeing 777, Airbus 320, McDonnell Douglas DC-9, Bombardier Canadair Regional Jet CL-65, Saab 340, Embraer 500, Embraer 505, SIAI-Marchetti S.211, and Aero Vodochody L-39 airplanes. He reported having a total of 15,000 hours of flight experience, including 12 hours in MiG 23 airplanes. He was an active Lieutenant Colonel in the Air National Guard. He reported having over 2,400 hours of military jet flight experience, including 50 combat missions. He also reported having formal training on ACES 11 (F-16), Northrop Seat (T-38), and Martin Baker Mk 16 (T-6A) ejection seats.
YIP annually hosted the Thunder Over Michigan Air Show. It had two hard-surfaced runways. Runway 5/23 was in use for the air show and was 7,543 ft long and 150 ft wide. Runway 9/27 was located along the north boundary of the airport and was 5,001 ft long and 100 ft wide.
The airplane impacted the ground about 1.7 miles and 160° from the approach end of runway 27 at YIP, and the main part of the wreckage came to rest about 600 ft and 35° from the initial impact point. The airplane was resting near an apartment building with damage to the exterior west wall of the building evident. Examination of the airplane’s flight control system was not performed, as the pilot reported no flight control difficulties during the flight. Further examination consisted of a tabletop review of the aircraft and engine logbooks provided by the PIC, the PIC’s formal statement following the accident, and photos taken of the accident scene.
The PIC provided a written statement to the NTSB after the accident that described the events of the day as well as a previous loss of engine power event in 2018, after which he replaced the fuel control unit (FCU).
A review of aircraft and engine logbooks provided by the PIC revealed an engine logbook entry for the installation of a new FCU on a page dated with the year 2018. The PIC stated that his mechanic purchased three new FCUs on his behalf, one of which was then installed on the airplane. It is not known whether the term ‘new’ meant recently manufactured or manufactured years ago with no operating time. According to the PIC’s postaccident statement, replacement of the FCU was thought to have fixed the engine anomaly experienced in 2018. The accident FCU had accumulated about 13 flight hours of use between 2018 and the day of the accident.
The PIC in his postaccident statement indicated that he believed the engine anomaly on the accident flight was due to a problem with the exhaust nozzle assembly actuation system. He also believed that the 2018 engine anomaly, which he had assumed was fixed with the replacement of the FCU, may also have resulted from an issue with the exhaust nozzle assembly actuation system rather than the FCU.
The engine fan blades exhibited multiple hard body impacts on the leading edges, multiple blade tip fractures on different blades around the circumference (that is, not localized), and circumferential scoring and rub marks on the spinner dome. The observed engine damage was consistent with the engine rotating under power at the time of impact.
Other than the PIC’s mechanic, the NTSB is unaware of any independent engine shop or manufacturer within the United States with the appropriate tooling and expertise to perform a teardown examination of the Tumansky R27F2M-300 engine. Therefore, no postaccident engine examination was conducted.
The airplane was not equipped with any flight data or cockpit voice recording equipment. No recording devices were identified during the wreckage examination.
The PRO reported that he initiated the seat ejection sequence when the airplane was about 350 ft agl and below 200 kts. Both pilots were ejected from the airplane, with the PRO ejected first, followed by the PIC.
According to the airplane Flight Manual, safe ejection is ensured under the following conditions:
During takeoff and landing roll, 0 ft altitude and at least 70 kts.
In level flight at speeds:
Up to 270 kts without any limitation in height agl
From 500 to 620 kts, at a height of at least 100 ft agl
From 620 to 650 kts, at altitudes of at least 3,300 ft agl
During descent at an altitude equal to or greater than the rate of descent multiplied by 5 (disregarding the time required for the decision and preparation for ejection)
Depending on the type of special flight gear employed:
Up to maximum ejection speeds, if the pilot wears a pressure helmet with the closed faceplate and a high altitude pressure suit;
At an airspeed up to 485 kts if the pilot wears a flight helmet with the visor lowered and with oxygen mask put on;
At an airspeed up to 380 kts when the pilot wears a flight helmet with the visor lifted and wears no oxygen mask or when he/she wears a pressure helmet with the faceplate open.
There were numerous videos found online that showed the crew ejection from the airplane. A postaccident review of the videos revealed the ejection seat parachutes (for both occupants) did not fully deploy until the occupants had descended to just above treetop level.
Another pilot with MiG 23 flight experience was contacted regarding the accident. He was formerly a United States Air Force (USAF) pilot, USAF test pilot, test pilot for a major defense contractor, and pilot with the National Test Pilot School. He had flown with the PIC in the accident airplane and was on the 2018 flight when the airplane’s engine previously lost power. He noted that the engine power loss they experienced in 2018 was similar to his knowledge of the accident engine power loss. In the 2018 event, the engine power loss occurred at high altitude, and he and the PIC chose to perform an air start of the engine. Before the air start, no other emergency procedures were attempted, and the engine regained power before landing. After landing, the FCU was found leaking, and the PIC replaced the FCU.
When asked about the ejection seat system on the airplane, he said it used the same ejection seats as MiG 21 airplanes and was not a “zero-zero” seat, meaning they could not be used at zero altitude and zero airspeed. When asked about the crew ejection during the accident flight, he stated that he had seen videos of the ejection and that he believed that the crew was ejected from the airplane about the last possible moment. He said that in the videos he saw, the flight crew was only under full parachute canopy for a few seconds before entering the water. He noted that, in his opinion, had this been a military crew ejection, the timing of the ejection would not be in question. He further stated that the biggest reason that ejection seats do not save more lives is due to delayed crew ejection. He added that he doubted the PIC’s intent to land the airplane in a field at the perimeter of the airport would have been a survivable scenario.
Postaccident review of radar and ADS-B data sources revealed no data for the flight useful to the investigation.
Analysis:
Both the front-seat pilot-in-command (PIC) and the rear-seat pilot-rated observer (PRO) of the Russian-manufactured fighter jet reported that the airplane’s engine did not respond to application of afterburner power during a display pass at an air show. According to the PIC, the engine was operating in a degraded power condition that was insufficient to sustain altitude and airspeed. The PIC maneuvered the airplane back toward the airport while he attempted to restore engine power.
The PIC believed that his corrective measures would have restored engine power; however, the PRO activated the crew ejection system before engine power was restored. The PRO reported that he inquired about ejection with the PIC but did not hear a response before he activated the ejection system; however, the PIC reported that he replied “no” in response to the PRO’s ejection inquiry and that he was ejected from the airplane while he was troubleshooting the loss of engine power and still flying the airplane. Although the PIC was completing corrective actions, engine power was not restored by the time of the crew ejection and, therefore, the investigation was unable to determine if his corrective efforts would have been successful.
According to the PRO, the ejection system was activated about 350 ft above ground level (agl) and below 200 kts. Both pilots were ejected from the airplane, with the PRO ejected first, followed by the PIC. The airplane continued in a left bank and descended into the ground about 1.7 miles from the runway. The airplane impacted the ground adjacent an apartment building and was destroyed by impact forces and a post impact fire.
Other than the PIC’s mechanic, the NTSB was unaware of any independent engine shop or manufacturer within the United States with the appropriate tooling and expertise to perform a teardown examination of the Tumansky R27F2M-300 engine. The PIC’s written statement addressed potential sources for degraded engine performance; however, the NTSB could not validate the PIC’s opinion of the reason for the loss of engine power. Based on photographic evidence, the engine was producing some power at impact; however, the level of power output could not be determined. Due to investigative support limitations and the extend of damage, the investigators were unable to determine the reason for the loss of engine power.
The airplane flight manual indicated that during a descent, the minimum safe altitude for crew ejection is calculated based on the airplane’s rate of descent and is equal to the rate of descent multiplied by 5. Based on the 350 ft agl altitude at ejection provided by the PRO, this altitude would be appropriate for ejection at a maximum rate of descent of 70 feet per minute (fpm). Although the airplane’s actual rate of descent was not known, it was likely significantly higher than the 70 fpm limitation at the time of crew ejection. Additionally, video evidence showed that the ejection seat parachutes did not fully deploy until the occupants had descended to just above treetop level. Therefore, the timing of the crew ejection was not premature. Given the serious injuries received by both occupants, crew ejection at a higher altitude may have reduced the severity of their injuries. Likewise, had the crew ejection been further delayed, the occupant injuries may have been more severe.
Probable Cause and Findings:
A reported partial loss of engine power while maneuvering for reasons that could not be determined.
I don't think my situation is unique.
