On May 31, 2006, about 1815 Alaska daylight time, a Bell 206L-1 helicopter, N45RP, operated as a Title 14, CFR Part 135 local sightseeing flight, sustained substantial damage when it collided with terrain while maneuvering in whiteout/flat light conditions on the Mendenhall glacier, about 11 miles north of Juneau, Alaska. The pilot and two of the six passengers received minor injuries; the remaining four passengers were not injured. The flight departed Juneau about 1720 in visual meteorological conditions for a glacier landing and air tour over the nearby mountains and glaciers. Use your browsers 'back' function to return to synopsisReturn to Query Page
During a telephone conversation with the NTSB investigator-in-charge (IIC) on June 1, the director of operations for the company related that the flight had landed on the Herbert glacier as a routine part of the air tour, and after departing the glacier, the helicopter headed south, towards Juneau. While maneuvering at low altitude over the Mendenhall glacier, the helicopter's main rotors struck the glacier, and the helicopter descended and crashed onto the ice field. The director of operations indicated that the pilot related to him that there were no mechanical problems with the helicopter, and that the sky was overcast, with rain showers and flat light conditions, making it difficult to discern terrain features on the snow/ice-covered glaciers. The director of operations also stated that the pilot may have been communicating with another helicopter pilot in the area, and may have been in the process of looking for the other helicopter.
The NTSB IIC spoke with a Juneau FAA Flight Standards District Office aviation safety inspector on June 1, who, with another FAA inspector, interviewed the pilot and passengers shortly after their return to Juneau. She stated that she and the other inspector also viewed a portion of a passenger's video recording of the accident flight, and the video displayed low visibility and flat light/whiteout conditions. In a written statement provided to the IIC, the other inspector who viewed the passenger's video and participated in the pilot and passenger interviews, noted that the passengers had been concerned before the accident about the lack of visibility, and one passenger said it was "pure white" and wondered how the pilot could see to fly. The inspector also characterized the flight conditions seen on the video as overcast and gray/white, with visibility less than a mile, and conducive to producing flat light/whiteout conditions, making it difficult to discern topographic relief. According to the FAA inspectors, the pilot stated that he was initiating a slow, right turn down the glacier, and could not discern the ground below him due to the flat light conditions. He reportedly said he did not see the snowfield prior to the main rotors hitting the ground.
The helicopter sustained substantial damage to the main rotor blades, tail rotor blades, tail boom, and fuselage.
The IIC interviewed the pilot of a helicopter operated by Temsco Helicopters (another local helicopter operator), that was transiting the glacier upslope, in the opposite direction of the accident flight. He described the visibility as between a 3/4 of a mile and 1 mile, with flat light/whiteout conditions in some areas. He indicated that he had announced his intentions to fly up the left side of the glacier, and the accident pilot responded with an acknowledgement and his position. He also stated that the visibility appeared to be worse on the side of the glacier where the accident pilot was. The Temsco pilot stated that he came within 3/4 of a mile of the crash site, but was unable to see the accident helicopter.
Discussions between the IIC and the FAA principal operations inspector (POI) assigned to the accident operator disclosed that the accident operator does have a flat light training program, and that the program essentially consists of some lecture, and the pilots viewing an FAA-produced DVD on the hazards and procedures for flying in flat light. The inspector was asked if he thought the use of a radar altimeter, in addition to the standard barometric altimeter, would have been helpful in assisting the accident pilot with determining his actual altitude above the snow/ice field, and thus reducing the potential for a collision with terrain. The inspector responded, "absolutely, they are priceless in those conditions." The IIC also discussed the value of using a radar altimeter when flying in flat light and reduced visibility with the pilot of the Temsco helicopter. He indicated that they were highly desirable, and helicopters so equipped were his first choice for flying over the ice and snowfields [Note: A radar, or radio, altimeter sends a radio pulse to the terrain below, and converts the length of time it takes the pulse to reflect and return into a nearly instantaneous altitude above terrain display in the cockpit. A barometric altimeter derives altitude from air pressure, and does not directly reference terrain clearance].
At the time of the accident, the accident operator had 11 helicopters in service, with several assigned principally to sightseeing trips over the local glaciers. According to the FAA POI, none of them were equipped with radar altimeters, and none were required to be. He did note that some other operators involved in sightseeing over the glaciers have voluntarily equipped their helicopters with radar altimeters.
On October 7, 2002, following a series of accidents involving helicopters while flying over snow/ice fields in flat light or whiteout conditions (several on the same ice field as this accident), the NTSB issued Safety Recommendation A-032-35, which recommended the FAA: "Require the installation of radar altimeters in all helicopters conducting commercial, passenger-carrying operations in areas where flat light or whiteout conditions routinely occur." In a letter to the Safety Board dated September 6, 2005, the FAA responded to the Board's recommendation negatively, indicating that they did not plan to implement the Board's recommendation. The Safety Board has classified the FAA's response and status of A-032-35 as: "Open-Unacceptable Action." The full recommendation letter and associated correspondence with the FAA may be viewed by following the links at: www.ntsb.gov/safetyrecs. The correspondence file only (Recommendation Report) is included in the public docket for this report.