Peach Springs, AZ, USA
N155GC
EUROCOPTER EC130
The pilot of the helicopter was conducting his third air tour flight of the day, transporting six passengers to the operator's plateau landing site, known as Quartermaster, on the south bank of the Colorado River within the Grand Canyon. He was appropriately rated for this flight and was experienced executing approaches and landings at Quartermaster. Following an uneventful flight to the area, the pilot began a descent and approach from across the river to a ravine on the west side of the landing site. The accident helicopter was the ninth of ten helicopters scheduled to land at the site that afternoon, and because all of the pads on the east side of the site were occupied, the pilot initiated a descending left turn toward a landing pad located on the west side of the site, aligning the helicopter on an east-northeasterly heading. Photographs of the landing site windsock near the time of the accident indicated winds at magnitudes of 15 kts or greater from the north-northwest, resulting in tailwind conditions during approaches to the west pads. A pilot on the ground at the landing site reported that the accident helicopter began to decelerate as it approached the landing pads and entered a nose-up attitude, then turned left toward the landing pads, transitioned through several pitch oscillations, and drifted aft. The left turn continued through 720° of rotation before the helicopter descended into a canyon just west of the landing pads and impacted terrain. Photos indicated that the helicopter’s final impact in the canyon was immediately followed by a postcrash fire. Postaccident examination of the helicopter and engine revealed no evidence of mechanical anomalies that would have precluded normal operation. Two pilots who landed just before the accident conducted their approaches in a similar direction as the accident pilot and both later reported that they encountered adverse wind. The pilot who landed just before the accident reported that he encountered wind conditions that necessitated full right pedal and nearly resulted in a loss of yaw control. The accident helicopter’s flight characteristics at the time of the accident would have included slowing airspeed, a high power setting, and a relative wind position that were all conducive to a loss of tail rotor effectiveness (LTE), thus it is likely that the loss of control was the direct result of LTE. The landing site was located on a plateau and provided limited approach options due to its local topography. At the time of the accident, potential demarcation lines (boundaries of updrafts and downdrafts) would have been on the pinnacles of ridges located along the approach to the Quartermaster west pads. Figure 8 shows a conceptual illustration of potential demarcation lines and wind directions based on the terrain and wind environment present around the accident site at the accident time, and suggests areas where downdrafts, updrafts and turbulence could have impacted the accident flight’s approach to the landing site. Figure 8. Conceptual display of demarcation lines at accident site The proximity of other pilots and passengers who witnessed the accident resulted in an immediate response to aid the occupants of the helicopter; however, the remote location of the accident site and communication difficulties between on-scene and outside resources made rescue coordination challenging and victim transport by helicopter to the hospital did not begin until about 6 hours after the accident. Although all seven occupants survived the impact, they all sustained significant burn injuries, and three of the occupants were likely unable to egress the helicopter. The most significant factor affecting occupant survival was the immediate postcrash fire. The accident helicopter was not equipped, nor was it required to be equipped, with a crash-resistant fuel system. Due to a lack of data regarding the crash dynamics and impact forces, the effectiveness of such a system, if installed, in delaying the onset of a postcrash fire could not be determined. The only source of local wind information at Quartermaster at the time of the accident was a windsock, which can only display wind speeds up to 15 kts. Further, windsocks cannot indicate the presence of downdrafts, turbulence, or any other local environmental conditions that may affect flight safety, particularly when landing in a confined area. The operator provided its pilots with a morning weather briefing on the day of the accident, which advised of gusty wind conditions in the area of the accident site forecast to increase throughout the afternoon. Weather advisories issued after the morning weather briefing, several hours before the accident, indicated a cold front proceeding through the area of the accident site with associated wind gusts and turbulence. This information was likely not captured by the operator and distributed to its pilots even though some of the forecasts included wind conditions above the maximum wind outlined in the company's general operations manual (GOM). Because there was no additional wind information at the landing site beyond the windsock, it could not be determined the actual wind conditions at the landing site at the time of the accident; however, pilots who landed before the accident pilot estimated the wind to be 15 to 20 knots, which is below that specified in the GOM. Although the morning briefing was not intended to be the pilots' sole source of weather information, it was likely the primary weather information the accident pilot received before the accident, as he had recently flown to Quartermaster and is not likely to have rechecked the weather.
HISTORY OF FLIGHT On February 10, 2018, about 1719 mountain standard time (mst), an Airbus Helicopters EC130 B4 helicopter, N155GC, was destroyed when it was involved in an accident near Peach Springs, Arizona. The pilot and one passenger sustained serious injuries, and five passengers were fatally injured. The helicopter was operated as a Title 14 Code of Federal Regulations (CFR) Part 136 air tour flight. On the day of the accident, the pilot performed a canyon landing, and an air tour flight before the accident flight. All of the day's flights departed Boulder City Municipal Airport (BVU), Boulder City, Nevada. Both the second flight and the accident flight had a destination of Quartermaster, an unimproved landing site regularly used by the operator within the Grand Canyon's Quartermaster Canyon. The pilot's second flight of the day took place in the early afternoon and returned at 1455. The accident flight departed at 1642. The accident helicopter reached the Hoover Dam about 1652 and entered the Grand Canyon West Special Flight Rules Area 50-2 about 1713, where the pilot flew the standard helicopter route known as the “Green 4 route.” The last radar return was captured at 1717 and depicted the helicopter about 3.5 nautical miles (nm) west of the accident site, consistent with a descent into the canyon to Quartermaster. The accident helicopter was one of ten helicopters scheduled to land at the site on the afternoon of the accident. The tour operation intended for the ten helicopters to sequentially land at Quartermaster and allowed for them all to be present at the landing site at the same time. The accident pilot stated that, during the approach to Quartermaster, he noted that the eight helicopters that had already landed were facing in different directions, indicating variable wind conditions. The combination of the windsock direction, orientations of the parked helicopters, and unoccupied landing pads on the west side of the landing area prompted the pilot to conduct an approach from the west and touch down on one of the west landing pads. He recalled that the two helicopters that landed immediately before him were on the west landing pads facing east, the same as his chosen approach direction, and noted that the windsock indicated wind from the north/northeast. The pilot stated that he normally remained on the north side of the Colorado River, crossing the river between 200 and 300 ft above ground level (agl) while approaching Quartermaster for landing. After crossing the river, he entered a left turning descent toward the landing area. (See figure 1.) He stated that, as he made the left turn, the helicopter encountered what he described as a “violent gust of wind” and began to spin, and as a result he was unable to maintain directional control. Figure 1. Graphical representation of typical approach to west pads A Papillon pilot on the ground at Quartermaster watched the accident helicopter as it approached from across the river and assumed that the pilot planned to land on the west pads based on his approach path. He reported that the helicopter decelerated and then entered an approximate 15° nose-up pitch attitude. While maintaining altitude, the helicopter began a left turn toward the landing site. According to the witness, during the turn, the helicopter transitioned into a level attitude, followed by a nose-low attitude. He further reported that the helicopter began to drift aft as the left turn continued and returned to a level attitude before it rotated 360° and began a descent. After a second 360° rotation, the helicopter collided with terrain. A postimpact fire ensued. Previous Approach and Landings at Quartermaster The first five helicopters to land at Quartermaster on the afternoon of the accident approached from the east and landed on the east pads, facing west. The next three helicopters landed on the west pads and used a similar approach as the accident helicopter. The tenth helicopter did not land due to the accident. PERSONNEL INFORMATION The pilot began his employment as a full-time pilot with Papillon Airways on June 3, 2013 and was trained by Papillon in the accident helicopter make and model. In 2014, the pilot transitioned into a role as a part-time pilot to pursue another career opportunity. At the time of the accident, the pilot’s primary occupation was in a different field (not as a pilot), but he continued flying for Papillon in a part-time capacity. Company training records revealed that the pilot’s most recent line check in accordance with 14 CFR Part 135 was accomplished in December 2017 and showed satisfactory grades for all areas of the examination; however, the lead pilot who conducted a portion of the pilot’s training in preparation for this line check reported that he had marked the pilot’s performance “unsatisfactory.” Specifically, he noted that the pilot had experienced difficulty maneuvering the helicopter during high wind conditions and did not have enough altitude as he turned during 180° autorotations. The pilot passed his check ride with another lead pilot 1-2 days later. According to the operator, at the time of the accident, the pilot had flown passengers into the Grand Canyon for them a total of 836 times, with 581 landings at Quartermaster. The pilot stated that he felt comfortable flying the Airbus Helicopters (formerly Eurocopter) EC130 B4 helicopter and landing at Quartermaster. Prior to becoming an air tour pilot for Papillon, the pilot flew air tours in non-turbine powered helicopters in the Midwestern United States. HELICOPTER INFORMATION Fuel System Crash Resistance On October 3, 1994, the FAA introduced improved fuel system crash resistance standards for newly-certified normal category helicopters. These standards, outlined in 14 CFR 27.952, are intended to minimize fuel spillage near ignition sources to improve the evacuation time needed for crew and passengers to escape a postcrash fire; however, they were not retroactively applicable to either existing helicopters or newly-manufactured helicopters whose certification and approval predated the revised standards. The accident helicopter, manufactured in 2010, was not equipped, nor was it required to be equipped, with a fuel system meeting the contemporary fuel system crash resistance standards. An option to retrofit the EC130 B4 with a crash-resistant fuel system was approved by the FAA in December 2017. According to the operator, the retrofit kits were not available to them until April 2018, after which they completed a retrofit of their existing fleet of EC130 B4 and AS350-series helicopters by August 2018. Airbus Helicopters issued Safety Information Notice 3281-S-28 on November 5, 2018, which recommended that operators of the EC-130 and AS350 helicopters retrofit them with 14 CFR 27.852 compliant crash resistance fuel systems. In July 2015, the NTSB issued Safety Recommendation A-15-12, which recommended that the Federal Aviation Administration (FAA) require the implementation of crash-resistant fuel system airworthiness standards for all newly manufactured rotorcraft, regardless of the original certification date, to reduce the risk of a postcrash fire in survivable accidents involving these rotorcraft. Section 317 of the FAA Reauthorization Act of 2018 prohibits helicopters manufactured after April 5, 2020, from flying in US airspace unless certified with a crash-resistant fuel system. Pending further information on the FAA’s efforts to address this issue with rulemaking, the NTSB had classified A-15-12 as “Open – Acceptable Response.” METEOROLOGICAL INFORMATION Surface Observations The automated observation at Grand Canyon West Airport (1G4), located at an elevation of 4,816 ft mean sea level (msl) about 2.6 nm northwest of the accident site, recorded wind from 330° at 15 knots (kts) with gusts to 19 kts at 1705. At 1725, the station recorded wind from 330° at 16 kts with gusts to 22 kts. Papillon and another helicopter operator each owned a weather station about 2 miles north-northwest of the accident site, at elevations about 1,200 ft msl. At 1700, the Papillon station reported wind from the north-northwest at 11 kts; at 1710, the wind was from the north-northwest at 11 kts gusting to 19 kts. At 1720, the wind was from the north at 11 kts, and at 1730, the wind was from the north-northwest at 12 kts, gusting to 24 kts. (The wind was recorded in miles per hour; the data has been converted to kts in this report.) The other station recorded a north-northwest wind at 10 kts gusting to 19 kts at 1700. The following three observations, recorded at 10-minute intervals, indicated northwest/north-northwest wind at 10 to 11 kts. Quartermaster was equipped with a windsock that was located near the landing pads. A photo of the windsock taken about 1713 showed the windsock in its fully extended position, consistent with a wind velocity of 15 kts or greater. (See figure 2.) Figure 2. Photograph taken at 1713 MST of windsock at Quartermaster Papillion Pilots’ Recollections of Wind Conditions at Quartermaster One pilot, who entered the canyon about 1646 and landed second in the sequence, encountered what he estimated to be a 20-kt headwind from the west while approaching an east pad. Another pilot, who entered the canyon about 1704 and landed fifth in the sequence, reported a northwest wind while landing on an east pad. He reported that he warned other pilots over the company radio frequency of a tailwind during the approach; however, only the sixth pilot to land recalled hearing this transmission. The pilot of the sixth helicopter to land, who entered the canyon about 1708, estimated variable winds between 15 and 20 kts. The seventh pilot to land entered the canyon at 1709. During his approach to the west pads, his intended destination, he recalled that the helicopter's tail swung rapidly due to strong winds and he applied significant right pedal and crabbed the helicopter to maintain the approach. The last helicopter to land before the accident entered the canyon at 1710 and touched down about 2 minutes before the accident occurred. The pilot had experience flying in mountainous terrain, knew of the presence of 15-20 kt winds from the east, and thus anticipated windshear during the approach. While turning toward the west pads, he experienced a strong wind that swung the nose of the helicopter about 90° to the left. The airspeed rapidly decayed and it required all of his effort to maintain control of the helicopter. As the helicopter began to descend, he increased collective to arrest the descent and was able to maintain control by pushing the cyclic forward and right to increase airspeed while applying full right pedal to keep the nose straight. He successfully landed the helicopter on one of the west pads. The accident pilot reported that he tried to be conscious of the wind during previous flights into Quartermaster and added that he had never experienced a violent wind shift like the one he encountered on the day of the accident. When discussing making the final turn to approach into Quartermaster, the accident pilot stated that “ninety percent of days are…it’s calm and you don’t think twice.” Weather Synopsis A National Weather Service (NWS) Surface Analysis Chart for 1400 showed a low-pressure center along the Utah/New Mexico Border. A cold front extended west from this low-pressure center, and the accident site was located just ahead of the front. In a subsequent Surface Analysis Chart issued at 1700, the cold front had moved south of the accident site into north-central Arizona. Clear skies were reported across the region except in far northern Arizona and southern Utah, which indicated overcast sky conditions. The NWS sustained wind speeds for the accident region showed forecasts for increasing wind speeds throughout the day. Upper Air Data A high-resolution rapid refresh model sounding valid for the accident location at 1700 was retrieved from the National Oceanic and Atmospheric Administration (NOAA) Air Resources Laboratory. The surface elevation of this model was run at 1,863 ft, about 400 ft higher than the terrain elevation of Quartermaster. The model showed wind from the north-northwest at speeds between 10 kts near the surface to about 20 kts near about 5,000 ft. Sounding calculations showed low-level wind shear near the surface. Weather Forecasts An Area Forecast Discussion (AFD) issued at 1637 reported a strong cold front and widespread wind gusts during the evening on the day of the accident. A previous AFD forecast a strong cold front to move through the region that afternoon and evening, with winds from the north to northeast at sustained magnitudes from 20-30 kts and gusts between 40-50 kts. An urgent Weather Message was issued by the NWS at 1008 effective for the accident site at 1800. The Weather Message referenced an NWS wind advisory, which indicated that wind would increase in the late afternoon, peak overnight, and decrease through the following morning. The wind was forecast to be 20-30 mph sustained with gusts of 30-45 mph and possible isolated gusts to 55 mph. A Graphical Forecast for Aviation was issued about 1500 and valid for 1700 that depicted clear sky conditions, a surface visibility of greater than 5 statute miles, and northwesterly surface wind gusts between 20 and 35 kts in the accident region. The closest Center Weather Service Unit issued a Meteorological Impact Statement at 1545 to expect gusty westerly wind of 25 to 35 kts gusting to 40 to 45 kts over the mountains and deserts on the afternoon and evening of the accident in the area of the accident site. Operator’s Weather Procedures According to Papillon’s General Operations Manual (GOM), “For flights conducted within the Local Tour Area, the Director of Operations (DO), Chief Pilot, Director of Utility Operations, or a Management Designee will determine the weather based on information obtained from an approved source.” Further, the GOM stated that pilot weather briefings are conducted as part of a daily morning safety briefing and the weather information would be posted on the bulletin board of the pilot break room. These briefings must include adverse weather advisories (SIGMET/AIRMET), current weather (METARs), terminal forecasts (TAF), area forecast, winds and temperatures, pilot reports and NOTAMS, if applicable. According to the DO, the morning briefings were conducted by a lead pilot and occurred about 0545. The accident pilot’s shift started about 4 hours after the morning weather briefing; however, he initialed the briefing sheet to indicate that he had reviewed the provided weather information. The operator’s daily weather briefing was a company-produced document that included current weather conditions, TAFs, area forecasts, NOTAMs, and AIRMETS/SIGMETS/PIREPS/TFRs. The briefing sheet for the day of the accident showed wind at 7 knots at 1G4. The area forecast portion of the briefing sheet included a synopsis that gusty winds from the north would spread southward and would be accompanied by a cold front but did not offer any further wind information. The briefing sheet also presented three NOTAMs, two AIRMETs, and the TAF for McCarran International Airport (LAS), Las Vegas, Nevada, which did not show any forecast weather events or wind conditions for Quartermaster. In addition to the weather briefing, the operator had a pilot’s station in the passenger building where pilots could access additional weather information, and their lead pilot monitored PIREPs and aviation weather data throughout the day. The company’s control tower staff could also relay weather information to the lead pilot, although this was not a required part of their duties. Interviews with several Papillon pilots revealed that the primary means of assessing the weather conditions before a flight included reports from pilots returning from the Grand Canyon and wind indicators near Quartermaster, the windsock at Quartermaster, and a weather station about 2 nm away. Several pilots stated that they would talk to other pilots at the terminal after returning from Q
A loss of tail rotor effectiveness, the pilot’s subsequent loss of helicopter control, and collision with terrain during an approach to land in gusting, tailwind conditions in an area of potential downdrafts and turbulence.
Source: NTSB Aviation Accident Database
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