BEECH A36 — Sparks, NV

What happened

The 73-year-old commercial pilot was on the fourth and final leg of a 950-mile round trip same day flight. As the airplane neared the airport, the pilot was told by the air traffic controller to expect runway 25 for landing. After the controller informed him of a delay for that runway, the pilot stated that he could accept runway 16L; the pilot was told to proceed for runway landing, but the runway was not specified, an instruction which he acknowledged. Shortly after establishing contact with the tower controller, who instructed the pilot to continue for runway 25, the pilot reported that the airplane was on a downwind leg for landing on runway 16L. The controller acknowledged and, rather than correcting the pilot, instructed him to continue inbound for 16L. At the time, runway 16R was being used for landing by two Boeing 757 (B757) airplanes in sequence, separated from each other by about 7 miles. The controller advised the accident pilot that a B757 was on a 9-mile final for runway 16R and cautioned him about wake turbulence, then cleared the accident airplane to land. Shortly thereafter, the pilot reported that he had "the airliner" in sight. At this time, one of the B757s was on a short final approach for 16R, about 4.5 miles ahead of and below the accident airplane. The other B757, which was the potential conflict, was about 5 miles away from the accident airplane at its 2-to-3-o'clock position. Given that the pilot's attention was likely focused toward the runway during this portion of the approach, it is likely that he misidentified the ATC-reported traffic as the B757 on short final, which landed soon after and likely resulted in the pilot relaxing his vigilance in looking for traffic. Shortly thereafter, the controller issued an all-aircraft advisory that the wind was from 250° at 17 knots with gusts to 20 knots. Although these wind conditions met or exceeded the airplane's maximum demonstrated crosswind capability for a landing on 16L, and the airplane was still well-positioned to revert to an approach to runway 25, the pilot continued toward 16L.

About 70 seconds after the pilot reported sighting the traffic, just after turning the airplane onto the base leg of the traffic pattern, the B757 passed about 1 mile ahead of and about 100 ft below the accident airplane. The investigation was unable to determine whether the pilot saw that B757, or if he did, whether he was cognizant of the potential for a wake vortex encounter and the flight path alterations necessary to avoid such an encounter. The pilot made no radio communications or flight path adjustments to indicate that he saw the B757 or tried to avoid its wake.

According to witnesses, the airplane's flightpath appeared normal as it approached the runway for landing. When the airplane was on about a 1/2-mile final approach, at an altitude of less than 200 ft above ground level, it suddenly rolled and descended to the ground. Ground scars and debris distribution was consistent with a near-vertical descent and impact. Examination of the wreckage did not reveal any evidence of pre-impact mechanical deficiencies or malfunctions that would have precluded normal operation. A wake vortex analysis study revealed that the airplane most likely encountered the wake vortices that were generated by a B757 landing on the parallel, upwind runway. The vortices were of sufficient size and strength to radically upset the airplane at an altitude too low to recover.

Had the controller informed the pilot that there were two B757s on final approach for 16R, it is likely that the pilot's traffic situational awareness would have been more complete. The pilot likely would have altered his traffic scan or questioned ATC further to ensure that he had identified the correct B757. The pilot's radio communications did not indicate any doubt about whether he had properly identified his traffic, and in postaccident interviews, the controller stated that he was certain that the pilot had correctly identified it. Had either the controller or the pilot specified the location of the traffic once the pilot reported it in sight, that information would have significantly improved the likelihood of detecting the pilot's identification error.

The safety of the approach sequence was dependent on assured separation of the airplane from the B757 and its wake. In this case, because both airplanes were being controlled by ATC in a radar environment, aircraft and wake turbulence (vortex) separation was the responsibility of the controller until explicitly transferred to the accident pilot. Although ATC requirements to apply pilot-based visual separation had been satisfied and it was the controller's intent to have the accident pilot maintain visual separation from the B757, the controller relinquished his separation responsibility without explicitly transferring that responsibility to the accident pilot. As a result, no separation services were being provided by the controller. The accident pilot's likely misidentification of his traffic, the controller's lack of awareness of that apparent error, and the controller's failure to monitor, detect, or intervene in a situation conducive to a wake vortex encounter enabled the accident to occur.

At the time of the accident, the pilot had been awake about 14.5 hours and had flown about 8.5 hours that day. Given the pilot's experience level, it is unlikely that he was not aware of the effect of either the extreme landing crosswinds or wake vortex behaviors and hazards, but for reasons that could not be not determined during the investigation, the pilot nevertheless continued his approach to land on 16L. Investigators were also unable to determine the effect of the pilot's long duty day on his mental acuity or explain the reasons behind several of his actions and decisions, including his vague communications with ATC regarding the landing runway, his decision to forego landing on a runway more favorable to the wind conditions, and his misidentification of the conflicting traffic.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.