Primary finding
Probable cause
The pilot's improper go-around procedure that did not ensure that the airplane was at a safe airspeed before raising the flaps, which resulted in exceedance of the critical angle of attack and resulted in an accelerated aerodynamic stall and spin into terrain. Contributing to the accident were the initial local controller's decision to keep the pilot in the traffic pattern, the second local controller's issuance of an unnecessarily complex clearance during a critical phase of flight. Also contributing was the pilot's lack of assertiveness.
Investigator assessment
Analysis narrative
The pilot was attempting to land the airplane at a busy airport with high volume airline traffic. While attempting to sequence the airplane between airplanes, the air traffic controller issued numerous instructions to the pilot, which included changing runways multiple times. The pilot was instructed to go around twice by the local controller; the first time because an air carrier airplane was overtaking the accident airplane and the second time because the airplane was too high to make a safe landing. During the airplane's third approach, a new local controller came on duty. On this approach, the pilot again had difficulty descending fast enough to make a safe landing, and she elected to perform another go-around. The new local controller then issued the pilot a lengthy clearance as the pilot was performing the go-around procedure. Data retrieved from the airplane revealed that, during the go-around, the pilot did not follow the recommended go-around procedure; specifically, the pilot did not attain a speed between 81 to 83 knots indicated airspeed (KIAS) before raising the flaps. Rather, the airplane's airspeed was 58 KIAS when the pilot raised the airplane's flaps while in a left turn, which resulted in exceedance of the critical angle of attack and a subsequent aerodynamic stall and spin into terrain. Postaccident examination of the airframe and engine did not reveal any anomalies that would have precluded normal operation. The air traffic control instructions given to the pilot during the three approaches were complex and potentially distracting. The initial local controller elected to keep the airplane in the traffic pattern rather than transferring the airplane to an approach controller for resequencing when airline traffic interrupted the pilot's first landing attempt and when the pilot displayed difficulty landing the airplane on her second landing attempt. The complex instructions from the second local controller during the pilot's go-around following her third landing attempt, were unnecessary at that time and likely distracted the pilot from monitoring critical flight parameters. The pilot was attempting to comply with ATC instructions throughout the flight and the pilot's actions are understandable as the instructions were largely consistent with the pilot's goal to land at the busy airport. However, compliance with ATC instructions greatly increased the pilot's workload as it led to an extended period of close-in maneuvering at a Class B airport due to the larger and faster airplanes converging on the airport. During this extended period of maneuvering the pilot did not assert the responsibilities that accompany being a pilot-in-command and did not offload the workload by either requesting to be re-sequenced, telling the controller to standby, or stating "unable." This allowed for an increased likelihood of operational distractions associated with air traffic communications and affected the pilot's ability to focus on aircraft control.
Source record
Factual narrative
HOU has 4 runways: 4/22, 35/17, 13L/31R, and 13R/31L. According to HOU tower personnel, in the period leading up to the accident, HOU was landing runways 4 and 35 and departing runways 4, 12L/R, and 35. Most of the traffic was landing on runway 4 and departing from runway 12R. The airplane was equipped with a Garmin G1000 Integrated Flight Deck and a Heads Up Technologies recoverable data module (RDM) data recorder. Flight data recorded by these devices were downloaded by the National Transportation Safety Board's Vehicle Recorder Division in Washington, DC. Review of the data revealed that, at 1308:19, the airplane began to pitch nose up, while at 63 knots indicated airspeed (KIAS) and 102.8 ft mean sea level (msl). The airplane began climbing at 9-11° nose up, while traveling at 66-74 KIAS with full flaps extended. According to ATC communications, at 1308:21 the pilot reported the go-around and the tower controller begin transmitting a clearance. At 1308:26, the airspeed was 74 KIAS, which was the highest airspeed that the airplane achieved during the climb out, and the airspeed then began to decrease. At 1308:36, the tower controller finished his clearance and began another part of the clearance at 1308:42 and continued transmitting past the last recorded point. At 1308:45, the airplane entered a left turn with the airspeed decreasing through 64 KIAS. At 1308:52, power was reduced from 94% to about 81%, with a corresponding reduction in engine parameters. The flaps were moved from full to half flaps at 1308:56, with the airplane at 13° nose up, 18° of left bank, and 62 KIAS. The flaps were fully retracted (0° flaps) at 1309:02 with the airplane in a 26° left bank and travelling at 58 KIAS. One second later, the airplane was in a 71° left bank, the pitch dropped to 5° nose low, and engine power increased to 90%. No further data were recorded. FAA Advisory Circular (AC) 61-98C, "Current Requirements and Guidance for the Flight Review and Instrument Proficiency Check," dated November 20, 2015, states, in part, that the intent of a flight review is a routine evaluation of the pilot's ability to conduct a safe flight. The AC further states that, regardless of the pilot's experience, the flight instructor should review at least those maneuvers considered critical to safe flight such as stabilized approaches to landings, slow flight, stall recognition, stalls, stall recovery, and spin recognition and avoidance. FAA Safety Team AFS-850 16-08, "Fly the Aircraft First," dated August 2016, provides a reminder to pilots to maintain aircraft control at all times. It states, in part, "The top priority – always – is to aviate." It further states, "Rounding out those top priorities are figuring out where you're going (Navigate), and, as appropriate, talking to ATC or someone outside the airplane (Communicate). It seems simple to follow, but it's easy to forget when you get busy or distracted in the cockpit." Data from the National Oceanic and Atmospheric Administration showed that, at the accident location, at 1309, the altitude of the sun was about 83° above the horizon, and the azimuth of the sun was about 158°. The Harris County Institute of Forensic Sciences, Houston, Texas, conducted an autopsy on the pilot. The cause of death was multiple blunt force injuries, and the manner of death was ruled an accident. The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed forensic toxicology on specimens from the pilot. Testing was negative for carbon monoxide and ethanol. The following substances were detected: Ibuprofen detected in urine Naproxen detected in urine Zolpidem detected in heart blood Ibuprofen and naproxen are non-steroidal anti-inflammatory drugs, and their use would generally not present a hazard to aviation safety. Zolpidem is a prescription medication used to treat insomnia and may impair mental and/or physical ability required for the performance of potentially hazardous tasks, such as driving, flying, and operating heavy machinery. Due to adverse side-effects, the FAA recommends waiting at least 24 hours after use of zolpidem before flying. On the pilot's most recent medical application, she reported the use of doxycycline and dapsone for acne. The use of zolpidem was not reported. A review of the pilot's logbook revealed that she received her private pilot certificate on May 2, 2014. According to the logbook, she had landed within Class B airspace at least four times. Her most recent flight in Class B airspace was to Dallas Love Field (DAL), Dallas, Texas, and consisted of a landing on May 30, 2016, and a takeoff on June 3, 2016. There was no evidence that she had flown to HOU before the accident flight. Interviews with the pilot's flight instructors and review of her logbook did not find evidence that the pilot had completed a flight review in the previous 24 calendar months, as required by 14 CFR 61.56(c). (Title 14 CFR 61.56(c) states that a person may not act as pilot-in-command of an aircraft unless that person has accomplished a satisfactory flight review within the preceding 24 calendar months.) The manufacturer's checklist for a balked landing/go-around states that the airplane should be pitched to maintain the best angle of climb, between 81 to 83 knots indicated airspeed (KIAS), before raising the flaps. The manufacturer's published stall speed at 0° bank angle, idle power, and flaps up is 69 KIAS. The stall speed at 0° bank angle, idle power, and flaps full down is between 59-61 KIAS. An excerpt from the pilot's operating handbook concerning stall speeds is located in the public docket of this investigation. All major airplane components were accounted for at the accident site. The nose of airplane was aligned about 330° magnetic. The propeller was separated just aft of the propeller flange. All three blades remained attached to the hub and displayed curling, chordwise scratches, and leading edge nicks and gouges. The wing remained attached to the fuselage. On June 9, 2016, at 1309 central daylight time, a Cirrus SR20 airplane, N4252G, impacted terrain following a loss of control during a go-around at William P. Hobby Airport (HOU), Houston, Texas. The private pilot and the two passengers were fatally injured, and the airplane sustained substantial damage. The airplane was registered to and operated by Safe Aviation, LLC, Moore, Oklahoma, under the provisions of 14 Code of Federal Regulations (CFR) Part 91 as a personal flight. Visual meteorological conditions prevailed, and a visual flight rules flight plan had been filed. The airplane departed from University of Oklahoma Westheimer Airport (OUN), Norman, Oklahoma, about 1000 and was destined for HOU. As the airplane approached HOU, a high-volume air carrier airport surrounded by Class B airspace, the pilot was given numerous instructions by air traffic controllers to sequence it between several Boeing 737 airplanes. An air traffic control (ATC) group was formed to review the interactions between the controllers and the pilot. The following information was extracted from the ATC group report, which is available in the public docket of this investigation. 1252:47 – The pilot contacted HOU tower, and the local controller cleared the pilot to land on runway 4 and told her to follow a Boeing 737 that was on a 3-mile final approach to runway 4. 1254:39 – The local controller directed the pilot to maintain maximum forward airspeed due to a Boeing 737 on a 9-mile final approach that was trailing the airplane and traveling 80 knots faster. 1256:58 – Due to the trailing Boeing 737, which was overtaking the airplane, the local controller directed the pilot to go around and fly runway heading. 1257:37 – The local controller instructed the pilot to make a right base to runway 35, informed her of another Boeing 737 on a 5-mile final for runway 4, and stated that she would be landing before the Boeing 737. 12