CEN23FA361 · Mikoyan Gurevich MIG-23UB

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.

Verbatim NTSB analysis and probable cause from the NTSB dataset