LAX07FA056

The pilot's inadvertent encounter with instrument meteorological conditions and subsequent failure to maintain terrain clearance. Contributing to the accident were the dark night conditions, fog, and mountainous terrain.

The emergency medical services (EMS) helicopter was performing a cross-country repositioning flight from a hospital back to its base during dark night conditions back over a routing that the pilot had flown 5 times that day and also earlier in the evening when they had transported a patient to the hospital. Visual meteorological conditions predominantly prevailed along the route of flight; however, analysis of the weather reports disclosed conditions consistent with broken to overcast clouds having bases at 4,000 feet msl in the vicinity of the accident site. An AIRMET had been issued for the area for IFR conditions, with mountain obscuration, precipitation, mist, and fog. The helicopter was equipped with a satellite-based tracking system that reports the helicopter's GPS location to the operator's ground base while the system is in operation, and the data for the accident flight was reviewed. The route of flight proceeded toward the apex of a mountain pass, which is the main transition route from one side of a mountain range to the other, where the helicopter's base is located. The tracking data indicated that the helicopter appeared to follow a major highway in the lower portion of the pass. The highway makes a large "S" shaped path as it gains in elevation toward the top of the pass, which is about 4,200 feet mean sea level (msl). The route along the highway is away from a well-lit major city area that has a well-defined light horizon, toward rising and dark terrain with no ground reference lights other than vehicles on the highway. Once at the top of the pass as the highway turns toward the northeast, the upper desert communities on the other side of the mountain range once again provide a well-lit and clearly defined horizon. Near the upper end of the pass, the helicopter's satellite derived flight track showed that it inexplicably diverged toward the east, away from the highway, instead of continuing to follow the highway into the upper desert valley. The helicopter collided with terrain about 0.7 nautical miles east of the highway at 4,026 feet msl. The accident site was located in a small ravine, near the base of a 100-foot tall electrical transmission tower that was located along the ravine's east ridge. During subsequent examination of the airframe structures, flight control components, and engines, no pre-impact anomalies were found that would have precluded normal operation prior to impact. While the operator was in the process of equipping its helicopter fleet with night vision goggles, the accident helicopter had not as yet been equipped with any enhanced night vision devices. The helicopter was equipped for instrument flight, including a 3-axis autopilot. The first fire department responders to the accident site reported that the area was covered by what they described as "intermittent waves" of fog that would suddenly form and then dissipate, which made it difficult to locate the wreckage.

"THIS CASE WAS MODIFIED JULY 29, 2008." HISTORY OF FLIGHT On December 10, 2006, about 1755 Pacific standard time, a Bell 412SP helicopter, N410MA, call sign "Mercy Air 2," impacted mountainous terrain near Hesperia, California. LifeNet, Inc., d.b.a. Mercy Air Services, Inc., was operating the helicopter under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The commercial pilot and two medical crew members were killed; the helicopter was destroyed as a result of the post impact fire. The cross-country repositioning flight departed Loma Linda University Medical Center (94CL), Loma Linda, California, at 1742, with a planned destination of Southern California Logistics Airport (VCV), Victorville, California. Visual meteorological conditions predominately prevailed along the route of flight, and a company visual flight rules (VFR) flight plan had been filed. Mercy Air 2 had transported an injured patient from Phelan, California, to Loma Linda, and was returning to their assigned base at the time of the accident. Mercy Air 2 had traversed through the Cajon Pass in the area of the accident site five times previously on the date of the accident. The accident flight was the first flight of the day that was conducted during night conditions. After departing the Loma Linda University Medical Center Heliport, the flight proceeded toward the Cajon Pass. The Cajon pass is one of the main avenues of transition between the San Bernardino/Riverside basin and the helicopter's base in Victorville. Satellite tracking data from the operator indicated that the helicopter appeared to follow the Interstate 15 (I-15) highway in the lower portion of the Cajon Pass. The highway makes a large "S" shaped route as it gains in elevation toward the top of the pass, which is about 4,200 feet mean sea level (msl). The route along the highway is away from a well-lit residential/industrial area having a well-defined light horizon, toward rising and dark terrain. Once at the top of the pass as the highway turns toward the northeast, the upper desert communities are once again well-lit. Near the upper end of the pass, the helicopter flight track indicated that it proceeded toward the east, away from the highway. The Safety Board investigator-in-charge (IIC) reviewed the data from the Outerlink system. The satellite data indicated that the helicopter departed from 94CL and flew towards the Cajon Pass in a northwest direction. The flight path then followed the northbound I-15 until it had almost reached the summit of the Cajon Pass. The Satellite tracking system tracked the helicopter as it continued toward the northeast while the Interstate turned toward the north. At the time of the accident, position data from the helicopter was downloaded to the company's flight tracking/dispatch center every 30 seconds, but the time reference was only recorded in whole minutes, for each whole minute there would be two position reports. Altitude data was not reported. Airspeed and heading information were derived from the position reports. At the second of two position reports from 1753, the helicopter was over or adjacent to the I-15. At the first position report of 1754, it was slightly southeast of the highway. At the second position report of 1754, the helicopter proceeded on a magnetic heading of 060 degrees, and had traveled about .3 nm from the first 1754 position report, diverging away from the highway to the east-northeast. At the first position report of 1755 (the last received report), the helicopter had traveled about .7 nm, on a magnetic heading of 064 degrees from the previous report, and was about .4 nm east of the Interstate. The accident occurred before the company's tracking software received a second position report from 1755. The accident location was on a bearing of 110 degrees from the last position report at 1755, having traveled about .4 nm to the crash scene. The helicopter collided with terrain about 4,026 feet msl, about .7 nm east of the Interstate. The accident site was located in a small ravine, near the base of about a 100 foot tall electrical transmission tower. The electrical transmission tower was located along the east ridge of the ravine. The tower was part of a section of electrical support towers oriented north-northeast to south-southwest, east of the Cajon Pass. The power lines supported by the towers were depicted on the Los Angeles area aeronautical navigational charts. A witness reported that he was in the area of Highway 138, and a side road that crossed the lower Cajon Pass railroad tracks. About 45 minutes after dark, he was looking north and initially saw what appeared to be the glow of a small grass fire, about three-quarters of a mile north of his location. About 5 seconds later he observed a large fireball. The glow of the fire was obscured by waves of fog that would drift over the area in patches. He described the fog as not very thick, but it would "swoop down" and dissipate at an estimated elevation of about 3,500 feet. The witness said that earlier in the day, he had been using a wind gauge to check the local wind conditions near Highway 138. He recalled that the winds averaged about 13 miles per hour (mph), with gusts to 29 mph. At the time of the accident, the wind was blowing toward the northwest. The post-crash fire was visible from I-15, and 911 call centers began receiving reports of the accident starting at 1800. Callers reported some fog in the area of the accident, obscuring the tops of the power transmission towers and mountain ridges near the top of the pass. The first fire department responders to the accident site reported that the area was covered by intermittent waves of fog, which made it difficult to locate the wreckage. First Responders reported that upon their arrival the wreckage site was fully engulfed in fire. The post impact fire consumed approximately 2 acres of mountainside. Weather conditions at the bottom of the pass were VFR, with the upper desert at the destination airport was clear. PERSONNEL INFORMATION PILOT Prior to being hired by the operator, the 46 year old pilot had 21 years of previous military service, 12 years of which were as a military helicopter pilot, and he accrued about 3,094 hours of military rotorcraft experience. He held a Federal Aviation Administration (FAA) issued commercial rotorcraft helicopter certificate, and a rotorcraft helicopter instrument certificate. The pilot was hired by the operator in December 2005, for the Twentynine Palms, California, base, which at that time, utilized Bell 222U helicopters. The pilot completed the initial hire training syllabus and a check ride with a company check airman. He then had 3 to 4 ride-alongs on Aeromedical flights, and then he began flying medical flights as the pilot-in-command. He moved to the Victorville base in August 2006, and completed the company's transition training for the Bell 412SP helicopters. His most recent Part 135 check ride was August 29, 2006, at the Victorville base, which was conducted by a company check airman. The check ride was 1.5 hours, of which .3 was under an instrument training device (hood). The check ride form noted that the pilot was not authorized the use of an autopilot under instrument flight rules (IFR) flights The pilot was not IFR current, and not authorized by his company to conduct medical flights under IFR conditions, or the use of night vision goggles under any flight conditions. Between his date of hire and the accident, he accrued about 220 flight hours, for a total of about 3,371 hours, which included about 57 hours in airplanes. The Victorville pilots work a 7-day on, 7-day off rotation, and work either a 0800 to 2000 or a 2000 to 0800 shift during their 7-day rotation. The pilot began a 7-day rotation on December 8, 2006, and worked 0800 to 2130. On December 9, he worked 0800 to 2030. On Dec