Pilot Debrief

DASSAULT AVIATION MIRAGE F-1 near Las Vegas, NV — 2021-05-24

Final reportWPR21FA203
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Date
2021-05-24
Location
Las Vegas, NV, USA
Airport
LSV
Aircraft
DASSAULT AVIATION MIRAGE F-1
Registration
N567EM
Category
Airplane
Highest injury
Fatal
Fatalities
1
Phase of flight
Approach

Probable cause

The pilot’s exceedance of the airplane’s critical angle of attack on approach and failure to fly a traffic pattern track consistent with a no-flap configuration. Contributing to the accident was the failure of the airplane’s flaps to extend while in the traffic pattern for an undetermined reason.

Contributing factors

Contributing to the accident was the failure of the airplane’s flaps to extend while in the traffic pattern for an undetermined reason.

NTSB narrative

A fighter jet airplane providing combat training support to the Department of Defense collided with terrain shortly after entering the final turn in the traffic pattern. The pilot was returning to the airport after completion of tactical area work. As the airplane began the final turn (a 180° turn to align with the runway), its airspeed was about 170 kts and slowing. Shortly after, the pilot reported that he was having a flap issue and the airplane’s descent rate increased from 1,000 fpm to more than 3,000 fpm. The airplane’s airspeed dropped to below the listed low-speed limitation without flaps (160 kts) for about the final 14 seconds of flight. The flight manual advises pilots to land at a speed between 195 and 215 kts if the flaps do not lower. At the last recorded data point, the airspeed was 135 kts and slowing. Shortly thereafter, the pilot initiated an ejection. The airplane subsequently struck terrain in a residential area and was consumed by a postimpact fire. Postaccident examination of the airplane revealed that the flaps were likely not extended. During the preflight check of the slats and flaps, the leading-edge slats operated appropriately but the flaps did not initially extend during the first cycle of the check. The pilot was able to correct the issue and completed at least two additional cycles during the operational checks of the slats and flaps with no further issue. Whether this flap issue was a reoccurrence of the ground check anomaly, or another cause could not be determined due to the post-crash condition of the airplane and the absence of onboard recorded data. Postaccident analysis of the bulb filament revealed that the airplane’s master failure warning light was showing an amber light indication. Which annunciator caused the amber light to illuminate could not be determined but an amber light indication allowed for delayed action for the issue. If a red light was illuminated, it would call for immediate action. No additional evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation of the airplane were observed. Failure of the flaps to extend would require additional speed to compensate for the loss of lift, which would increase the airplane’s turning radius. Because the traffic pattern’s normal ground track is based on the airplane being configured with the flaps extended, a no-flap configuration would require the airplane to increase bank and angle of attack (AOA) to maintain the track. However, insufficient thrust was available to overcome the configuration issue and increased AOA. Under a failed flap scenario, the pilot would have needed to maintain adequate airspeed, AOA, and rolled out of bank and discontinued the final turn for an airplane configured with the flaps extended and then flown a traffic pattern ground track consistent with a no-flap configuration. The pilot likely maintained his ground track during the final turn in order to reduce the chance of conflict with potential landing traffic on the opposite runway if he rolled out of bank and pattern/airspace restrictions. It is likely that the pilot initiated an ejection outside of the airplane’s ejection seat minimum altitude ejection envelop due to the airplane’s increased bank, decreased airspeed, low altitude, and sink rate.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have declared an emergency earlier or executed a go-around.

NTSB coding

Evidence available

  • ATC audio
  • Video
  • FDR / data
  • 29 docket documents
View NTSB final reportView NTSB docket

Docket documents29

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