WPR14TA149

The pilot's decision to attempt a mission at night with known en route weather conditions below operating minimums, likely due to self-induced pressure, and then continue flight beyond the alternate landing airport as weather conditions deteriorated, which resulted in the pilot experiencing spatial disorientation. Contributing to the accident were the pilot's fatigue, his failure to recognize that mist had formed on the inner surface of the windshield, his complacency due to the effectiveness of the night vision goggles, and his failure to use the radar altimeter.

The intent of the public aircraft flight was to transport an injured dog from the Sheriff Department's K-9 division to an urgent care facility after it had been shot while on duty. After arriving at the Sheriff's Air Support Unit (ASU) headquarters about 0100, the pilot discussed the weather conditions with the on-duty command pilot and confirmed that visual meteorological conditions prevailed at both the departure and arrival airports. He was aware that a weather front was moving through the area and that he would likely encounter instrument meteorological conditions while en route. Therefore, he planned to use an airport about halfway along the route as a backup landing site if the weather conditions deteriorated. The pilot's decision to attempt the flight with known deteriorating weather conditions was likely due to self-induced pressure to complete the flight because of the dog's injury. The departure was uneventful, but, as the helicopter approached the alternate airport, it encountered light rain, strong wind, low clouds, and fog. The pilot decided to proceed and see if the helicopter could traverse a pass east of the airport. However, once the flight got beyond the lights of the city, the pilot lost all visual reference after flying into clouds; the helicopter was about 500 ft above ground level at this time. He decided to slow the helicopter and initiate a gradual descent to exit the clouds. Unknown to the pilot, the windshield had misted up due to a water leak, which limited the effectiveness of the night vision goggles (NVG) that he and the tactical flight officer (TFO) were using for the flight. During the descent, the TFO realized that the windshield had fogged up because he could still see out of the side window, and the pilot turned on the de-mister. Shortly after, a highway came into view, and the helicopter struck its surface about 5 miles past the alternate airport. The helicopter bounced and then rotated about 180 degrees. It appeared to be handling normally, so the pilot chose to return to the alternate airport. Upon landing, he discovered that the helicopter had sustained substantial damage. The weather conditions at the alternate airport were below the ASU minimums both before takeoff and during the flight. However, the ASU did not have formal risk assessment procedures in effect. The weather conditions at night and the misted windshield would have been conducive to the pilot's experiencing spatial disorientation. Although the helicopter was equipped with a radar altimeter, its audible and visual alert functions were turned off at the time of the accident. If the pilot had used the radar altimeter, it would have given him an opportunity to react when the helicopter reached or descended below a predetermined altitude. The pilot, who was also the ASU's chief flight instructor, admitted that the typical effectiveness of the NVGs likely led to complacency on his part. The pilot had been working the day leading up to the accident and had been awake for about 16 hours. He reported that he was about 2 hours into restful sleep when he was woken to perform the mission. Therefore, he attained minimal rest for the mission, which was performed during a time when he would otherwise be asleep and likely degraded his performance and decision-making ability.

The ASU was comprised of six pilots and three TFO's. Depending on availability, the pilots would also perform the duties of a TFO. The unit also drew on the resources of a group of search and rescue (SAR) volunteers. Two of the pilots were instrument rated. Depending on the day of the week, the ASU shared aviation related SAR responsibilities with the Kern County Fire Department. With the fire department providing support Monday through Wednesday, and the ASU covering the remaining four days. The ASU operated three fixed wing aircraft, and five helicopters, which included two Bell OH-58's, two McDonnell Douglas MD 500's, and one Bell UH-1. Most of the routine and scheduled maintenance was performed by mechanics in-house. According to the operations manual, the ASU was managed by an officer-in-charge (OIC), with training scheduling, oversight, and planning performed by the chief flight instructor. According to the manual, a position of Safety Officer had been created to "Establish a safety manual, safety practices, and to provide recommendations for the OIC regarding safety items." However, the OIC revealed that a Safety Officer had not been assigned, and that the safety manual only contained broad safety objectives that were not specific to ASU operations. There was no formal safety management system (SMS) in place beyond verbal and written discrepancy reports to the OIC and chief flight instructor. According to the pilot, there was no specific risk assessment procedure prior to flight, primarily because most flights are routine in nature. Airborne Law Enforcement Association Standards The Airborne Law Enforcement Association (ALEA) is a non-profit association comprised of local, state, and international public aircraft operators. The association's mission is to "promote and advance safe, effective and efficient aviation operations in public safety through voluntary compliance with Commission standards validated through the accreditation process." The ALEA provide a series of guidelines and resources, which a public operator may choose to utilize as either an operations template, or towards accreditation. According to an ALEA representative, the organization has over 3,000 members, and eight public operators have attained accreditation. According to the OIC, although the ASU has not attained accreditation, all of the pilots are members, and typically two or three attend ALEA conferences annually. Night Vision Goggles All ASU pilots received training in the use of NVG's during the period from 2006 through 2009 by Aviation Specialties Unlimited of Boise, Idaho. All subsequent recurrent training was performed by both the accident pilot and the deputy flight instructor, who both then cross-train each other for currency. All pilots are required to maintain currency every 90 days. The accident pilot did not recall any specific training which warned of the adverse effects of windshield fogging while using NVG's. He stated that the windshield demister was turned off at takeoff, and that this was required by checklist because it utilized engine bleed air. According to representatives from Aviation Specialties Unlimited, windscreen condition and its effects on NVG performance are discussed during training. Additionally, the 2008 ground school student handout stated the following in the section entitled, "Indications of Restrictions to Visibility at Night": "NOTE: Aviators may fail to detect a gradual increase in cloud coverage (fog, haze, or precipitation) and may inadvertently enter the clouds. Occasionally look under the goggles (unaided) and check for indications of deteriorating weather conditions." The Part 135 Operations section of the most current student handout specifically states the following, "Inspect aircraft windscreen and windows for condition and cleanliness. Particular attention should be paid to ensure that the windscreen and windows do not have a layer of dust on the exterior or haze that can form on the interior of the windscreen. A light layer of dust or haze, just like light fog or mist, can significantly degrade visual acuity." Radar Altimeter The radar altimeter was an analog type, with a needle which triggered both an audible and visual warning when its altitude was reached. The pilot reported that the audible and visual alerts were turned off at the time of the accident. He stated that his standard practice when flying the UH-1 helicopter on SAR missions is to set the altimeter to a pre-determined hoisting height, and that for the accident flight he would most likely have set it to trigger at 300 feet, thereby giving him ample opportunity to react. He conceded, however, that not setting it for this flight was an oversight, and that the urgency of the mission could have contributed to this. He further stated that complacency was a possible factor due to the excellent situational awareness typically provided by NVG's. He stated that setting the radar altimeter is not a checklist item because it is mission specific, but that it should be added to the checklist, possibly in the form of "set radar altimeter trigger as needed." He further noted that some pilots prefer not to set or arm the radar altimeter due to the distracting beeping sound it creates. Weather Minima The ASU operations manual, Helicopter - Prohibited Operations section, stated that night mountain operations with ceiling or visibility less than 1,000 ft agl and 3 statute miles are strictly prohibited. In the Operator/Owner Safety Recommendation section of the NTSB Form 6120.1 "PILOT/OPERATOR AIRCRAFT ACCIDENT/INCIDENT REPORT", the pilot stated that the accident could have been have been prevented by: "Obtain[ing] a complete official weather briefing in person. Avoid flight operations in marginal weather conditions at night." The closest weather reporting station was located at Tehachapi. Five minutes before departure it reported wind from 300 degrees at 15 knots with gusts to 22 knots, 7 miles visibility, broken ceiling at 500 ft agl, overcast skies at 1,300 ft agl, temperature 4 degrees C, dew point temperature 4 degrees C, altimeter 29.93 inHg. At 0135, the visibility remained the same, with scattered clouds at 400 ft agl, broken ceiling at 800 ft agl, and overcast skies at 1,700 ft agl. Next Generation Radar (NEXRAD) LEVEL-II data imagery for the period 1245 to 0158 revealed rain showers forming and moving eastward into the mountainous terrain east of Bakersfield. An area forecast, issued about 6 hours prior to the accident, indicated rain showers and ceilings near 3,000 ft for Bakersfield, along with isolated showers for the mountains and 20 knots wind, gusting to 30 knots. An AIRMET was also issued about that time indicating mountain obscuration and turbulence. The pilot was the chief flight instructor for the ASU. He stated that he had been flying fixed wing aircraft since 1975, and helicopters since 1980. His flight experience was primarily within the fields of electronic news gathering, emergency medical service, and law enforcement. He held an airline transport pilot certificate with ratings for helicopter-rotorcraft, along with a commercial certificate with ratings for airplane single engine land, multiengine land, and instrument airplane. He also held a flight instructor certificate with ratings for helicopter. He reported a total flight experience in all aircraft of 16,110 hours, with 6,193 in the accident make and model. He had flown for 14 hours during the preceding 30 days, three of which were in the accident make and model. The pilot held a second-class medical certificate issued on September 24, 2014. It had no limitations or waivers. The TFO did not hold a pilots certificate. The pilot submitted a sleep and activity log for the 72-hour period leading up to the accident. Each day he went to sleep at 2130, and woke at 0530. Although he was on duty from 0800 to 1600 on both prior day