BOEING 757-236 near Tulsa, OK — 2022-06-08

Probable cause

The flight crew’s misidentification of the intended landing runway. Contributing to the incident were (1) the flight crew’s failure to perceive and correctly interpret visual and auditory indicators – including electronic guidance – that they were approaching the incorrect runway which was likely the result of a degradation in cognitive function brought on by working within their window of circadian low, increased workload, and fatigue, and (2) the air traffic controller’s failure to monitor the arriving flight after issuing a landing clearance.

Contributing factors

Contributing to the incident were (1) the flight crew’s failure to perceive and correctly interpret visual and auditory indicators – including electronic guidance – that they were approaching the incorrect runway which was likely the result of a degradation in cognitive function brought on by working within their window of circadian low, increased workload, and fatigue, and (2) the air traffic controller’s failure to monitor the arriving flight after issuing a landing clearance.

NTSB narrative

As the Federal Express (FedEx) flight 1170 flight crew approached the Tulsa International Airport (TUL), they mis-identified runway 18R as runway 18L and continued their approach and landing on runway 18R. After touchdown and hearing the “3000 feet remaining” call from the automated runway awareness and advisory system (RAAS), the captain recognized they had landed on the incorrect runway, applied heavy braking and was able to exit the runway at the final taxiway. Figure 1. Final approach screenshot illustrating flight alignment with runway 18R. Available Cues As the flight was in visual meteorological conditions, there were available visual cues external to the airplane, to distinguish the runways from one another in their lighting, configurations, and the surrounding environments. These differences were all salient visual cues that should have enabled the flight crew to distinguish one runway from the other in visual meteorological conditions. The flight deck provided both pilots with a primary flight display (PFD) and navigation display (ND), while only the captain had a heads up display (HUD) to aid in monitoring the progress of the flight. The first officer (FO) told investigators that the electronic glideslope on the PFDs and HUD which was set for 18L looked “normal” however he was concerned about their alignment with the visual glideslope (18R precision approach path indicator (PAPI)). The FO failed to realize that ultimately the airplane was showing “low” on the visual glideslope because of the parallel runways’ displaced thresholds. Cognitive Phenomena The flightdeck visual cues that were perceived by the flight crew were 1) the horizontal situation indicator (HSI) deviation bar being off to the left on the FO’s PFD; and 2) the captain’s HUD localizer being off to the left. It was FedEx policy to back up all approaches with the instrument landing system (ILS), however the flight crew appeared to discount the information their instruments were providing in favor of the view they had of the runway and understanding of their circumstances. The flight crew focused on their flightpath and decent rate for the runway they had already visually acquired, and the multiple visual cues that they were misaligned were not recognized. Once they took manual control of the airplane and adjusted to the desired precision approach path, the flight crew proceeded with the landing without engaging in further confirming acts. This behavior is consistent with the psychological phenomenon of plan continuation bias which is the unwillingness to deviate from a previously determined course of action, despite the arrival of circumstances precipitating the need for a change. Once a plan is committed to, it becomes increasingly difficult for stimuli or changing conditions to be recognized. Plan continuation bias is exacerbated by fatigue. In this incident, the flight crew was working within the window of circadian low and under circadian disruption. While the captain, who was the pilot flying, stated that he was not fatigued during the incident flight, he had been awake for more than 15 hours prior to the incident occurring and was likely experiencing fatigue due to chronic and acute sleep debt due to limited sleep in the days preceding the incident. The flight crews lack of recognition of their error was likely affected by fatigue, plan continuation bias, and their inability to perceive and efficiently integrate available information. Operator Fatigue Risk Management When creating flight schedules FedEx determines the potential risk for fatigue for each pairing by using the Karolinska Sleepiness Scale (KSS) on a 1-9 scaled rating. In evaluating the pairings FedEx also collaborates with the Airline Pilots Association (ALPA) who uses SAFTE-FAST which incorporates both the KSS and the Psychomotor Vigilance Test (PVT) on a scale of 1-100% (100% being peak wakefulness). The resulting scores are then compared. A KSS score of 7 or higher, or a SAFTE-FAST score of 70% or lower, typically indicated the pairing was of high risk and needed further review. The FedEx assessment of the incident flight pairing was a KSS of 6.39 and the score was established using the assumption that the flight crew would nap during their hub-turns. The ALPA assessment of the pairing was a 76.0% SAFTE-FAST score which also incorporates the nap assumption. FedEx did not publish KSS pairing scores, nor did they provide the scores (including the 30-minute nap assumption) to the flight crew. FedEx crews were expected to nap on a hub turn but were not told that a nap is expected or why that expectation exists. When asked why they adopted this policy, FedEx fatigue risk management program (FRMP) manager expressed concern over overburdening flight crews with additional information. The manager stated that FedEx feels that notifying flight crews of the pairing fatigue score, and what assumptions are factored into the obtaining of that score, is unnecessary and that FedEx’s current training program effectively addresses flight crew expectations and what fatigue mitigations are available. In this incident, the captain chose to abandon his nap attempt during the hub turn when he was unable to fall asleep. After about 30 minutes he decided to prepare for the next phase of his schedule. In failing to obtain a nap during the hub-turn, the captain unwittingly increased his fatigue score from within limits to high risk (7.4) on the KSS. Air Traffic Control (ATC) ATC awareness of the traffic approaching the airport provides an additional barrier to trap and correct errors, such as aircraft misalignment during landing. The tower controller’s failure to monitor the flight throughout the duration of its progress resulted in a missed opportunity to notify the crew and correct the misalignment before landing. Expectation bias occurs when a person hears or sees something or behaves in a way based on what he or she expects rather than what is actually occurring. Past experience or repetition can exacerbate this issue. In this incident, the controller had a reasonable expectation that the flight — a late night/early morning operation recurrent to TUL — would approach and land on the assigned runway. Consequently, she directed her attention away from the flight to other tasks. Because she was not monitoring the flight, she was unable to confirm its alignment on the correct runway nor was she able to provide corrective action to prevent the wrong surface event.

Analysis

Primary failure mode: Human factors
First missed decision gate: Captain should have acknowledged PAPI lights indicating they were below glidepath.

NTSB coding

Evidence available

CVR
ATC audio
FDR / data
ADS-B / radar
Photos
27 docket documents

View NTSB final report View NTSB docket