Cascade, ID, USA
N65EW
WALKER EDGAR E GLASTAR
The private pilot, who had no mountain flying instruction, planned to fly a friend's newly-purchased experimental amateur-built airplane from Idaho to Georgia. After he took delivery of the airplane at one airport in Idaho, the pilot flew to another Idaho airport to meet his pilot-rated cousin. The next morning, the two departed in the airplane for an airstrip situated about 38 miles to the northeast, at an elevation about 5,800 ft above mean sea level (msl). The aeronautical chart of the region depicted mountainous terrain between the two airports, with peaks ranging from about 6,700 to 8,700 ft msl. While en route, the pilot entered a canyon and realized that the airplane was unable to outclimb the rising terrain. The pilot began a course reversal turn to escape the canyon, but during the turn, the airplane experienced an aerodynamic stall and impacted the ground. The airplane was destroyed, the pilot received serious injuries, and the passenger was fatally injured. The impact site was at an elevation of about 7,500 ft. The pilot's preparations for the flight were minimal, and he did not explicitly plan out the flight route or altitudes to ensure sufficient terrain clearance margins. The pilot did not reside in mountainous terrain, and had not taken any mountain-flying training courses. The pilot did not have or use any paper charts before or during the flight and did not program his intended flight route into his GPS device, which was equipped with a terrain database and terrain display and warning capability. Prior to the accident, the pilot had only accrued about 1 hour in the accident airplane make and model. After the accident, the pilot reported that he had over-estimated the airplane's climb performance. Aside from climb speeds, there was no climb performance information in the airplane Owner's Manual (OM). Because the pilot did not specify whether he used the airplane's best angle of climb airspeed for the climb, his conduct of the climb could not be evaluated, and the effect of the actual climb performance on the outcome could not be determined. Mountain flying training guidance advocates that when flying in canyons, pilots should select a flight path near the side, as opposed to the center, of the canyon in order to provide the maximum amount of terrain clearance in the event a course reversal turn becomes necessary. Because the pilot did not specify any details regarding the lateral position of the airplane before or during the course reversal turn, the pilot's execution of the turn could not be evaluated, and its effect on the outcome could not be determined. An airplane's minimum-radius turn requires use of the lowest airspeed and highest bank angle that still provide sufficient stall margin. Because the pilot did not specify the speed or bank angle that he used for his course reversal turn, the pilot's execution of the turn could not be evaluated, and its effect on the outcome could not be determined. The OM did not provide actual stall speed information, and the airplane was not equipped with a stall warning system. Because the weight, configuration, bank angle, and actual performance of the airplane were not known, the actual stall speed could not be determined. Although the pilot had deployed partial flaps at an undetermined time just prior to or during the turn in order to reduce his stall speed, that configuration change alone was insufficient to prevent the stall. Because the airplane dynamics and pilot responses were not known, the specific reason(s) for the stall were not able to be determined. The pilot's inadequate flight planning, preparation, and navigation, combined with his lack of familiarity with the airplane's performance capability, resulted in the airplane entering a canyon that the pilot was unable to exit by outclimbing the terrain. The pilot's decision to reverse course was either too late, and/or his execution of the course reversal turn was insufficient to enable successful escape from the canyon. During the course reversal turn, the airplane experienced an aerodynamic stall and impacted terrain.
HISTORY OF FLIGHTOn September 2, 2017, about 1030 mountain daylight time, an experimental, amateur-built GlaStar GS-1, N65EW, was destroyed when it impacted terrain while maneuvering above a wilderness area about 15 miles east-southeast of Cascade, Idaho. The private pilot was seriously injured, and the pilot-rated passenger was fatally injured. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed in the area, and no flight plan was filed for the flight, which departed High Valley Swanson Airport (ID35), Cascade, Idaho, at an unknown time and was destined for Sulfur Creek Ranch Airport (ID74), Cascade, Idaho. According to the previous owner (referred to as the seller) of the airplane, he lived in Idaho and based the airplane at Nampa Municipal Airport (MAN), Nampa, Idaho. About 2 weeks before the accident, he sold the airplane to another individual (referred to as "the buyer") who lived in Georgia. Several days before the accident, the buyer notified the seller that he (the buyer) would have a friend of his (the pilot), who also lived in Georgia, come to Idaho to pick up the airplane and fly it back to Georgia. The day before the accident, the pilot met the seller at MAN to complete the transfer of the airplane. The seller offered to fly with the pilot in order to familiarize him with the airplane, but the seller said that he could only do that if he (the seller) could fly from the left seat, since the seller had never flown from the right seat. Alternatively, the seller offered to provide a flight instructor if the pilot preferred to fly from the left seat; the pilot opted for this course of action. Later that day, the pilot and instructor flew the airplane for about 1 hour, after which the ownership transfer was completed. The pilot told the seller that he was leaving for Georgia the following morning, and did not mention any other flight plans to the seller. About 1800 the next day, the seller texted the pilot to ask how the return flight was progressing, and the pilot informed him of the accident. According to the pilot, his cousin, who was also a pilot, lived in Idaho. The pilot flew from MAN to ID35, where he met his cousin and remained overnight. The next morning, the two departed in the airplane, with a destination of ID74. While enroute to ID74, the pilot flew into a canyon and eventually realized that the airplane was unable to outclimb the terrain. The pilot began a right turn to escape the canyon, but the airplane stalled and impacted the ground. The pilot was able to use his mobile telephone to notify authorities of the accident and fatality. About 3 hours after the accident, a US Forest Service helicopter rendered assistance to the pilot. About an hour later, first responders were lowered to the pilot to prepare him for aerial extraction. According to the helicopter pilot who effected the recovery of the pilot, smoke from a nearby forest fire reduced visibility somewhat, but the smoke was "not an issue" of impediment or concern. PERSONNEL INFORMATIONPilot Federal Aviation Administration (FAA) records indicated that the pilot held a private pilot certificate with an airplane single-engine land rating. His most recent FAA second-class medical certificate was issued in February 2017. On his application for that certificate, the pilot indicated that he had a total flight experience of 998 hours. According to the seller, the pilot stated that he did not have any backcountry flight experience, but that he hoped to move to Idaho and begin gaining backcountry flying experience. Pilot-Rated Passenger FAA records indicated that the passenger's most recent commercial pilot certificate, which included single-engine land, multi-engine land, and instrument airplane ratings, was issued in May 2003. His most recent FAA third-class medical certificate was issued in August 2001. No details of his flight experience, including total flight time, recency of experience, or mountain/backcountry training or flight time were obtained. The pilot did not provide any information regarding his cousin's participation in the planning or execution of the accident flight. AIRCRAFT INFORMATIONFAA records indicated that the airplane was manufactured in 1998 and had an empty weight of 1,331 lbs. The records indicated that the most recent seller was the third owner, and that he had purchased the airplane in November 2016. The airplane was equipped with a normally-aspirated Lycoming O-320 series engine, which had accumulated about 40 hours since the seller had it partially overhauled a few months after his purchase. The seller stated that the maximum allowable gross weight was about 1,990 lbs, and that the total fuel capacity was 50 gallons. Fuel records at MAN indicated that the airplane was fueled with 38.9 gallons the evening before the accident, several hours after the ownership transfer was completed. METEOROLOGICAL INFORMATIONReview of meteorological information indicated that visual meteorological conditions (VMC) existed in the vicinity of the accident site about the time of the accident, and first responder reports indicated that the area remained VMC for most of the day. Based on the upper air sounding data for the accident site for 1000 local time, the temperature would have been about 19°C at the accident site elevation. AIRPORT INFORMATIONFAA records indicated that the airplane was manufactured in 1998 and had an empty weight of 1,331 lbs. The records indicated that the most recent seller was the third owner, and that he had purchased the airplane in November 2016. The airplane was equipped with a normally-aspirated Lycoming O-320 series engine, which had accumulated about 40 hours since the seller had it partially overhauled a few months after his purchase. The seller stated that the maximum allowable gross weight was about 1,990 lbs, and that the total fuel capacity was 50 gallons. Fuel records at MAN indicated that the airplane was fueled with 38.9 gallons the evening before the accident, several hours after the ownership transfer was completed. WRECKAGE AND IMPACT INFORMATIONThe airplane impacted terrain and came to rest on an upsloping, rocky clearing in a forested area on the sidewall of the canyon. The impact site was located about 14 miles west-southwest of ID74 at an elevation of about 7,500 ft msl. Damage to several trees was consistent with them being struck and cut by the airplane just before ground impact. The fuselage was aligned in about the same direction as the tree cut swath. There was no fire. The wreckage was tightly contained; with the exception of the horizontal stabilizer/elevator and the propeller, all components remained attached to the airplane. The two separated components were found in close proximity to the main wreckage, and their locations and damage patterns were consistent with separation during the impact sequence. The cockpit/cabin was partially crushed, and torn open by impact. Due to impact damage, the pre-impact position of the flaps could not be determined. The left flap was found nearly fully retracted, while the right flap was found near the fully-extended position. The left wing was canted forward about 80° and the right wing was canted aft a similar amount. The left wing forward and right wing aft displacements were consistent with impact during a spin in the airplane nose right direction. The wreckage was not recovered. ADDITIONAL INFORMATIONFlight Route Planning and Navigation No ground-based radar tracking data were available for reconstruction of the airplane's flight path. In his narrative statement on his NTSB accident reporting form, the pilot indicated that he was using GPS as his navigation tool. In additional communications to the NTSB, the pilot reported that he had previously used a Garmin GPSMap 295, but for this trip, he had access to an iPad equipped with the Foreflight application. The iPad/Foreflight hardware/software combination is capable of presenting altitude, navigation, weather, and traffic information. "Geo-referencing" is the term used to describe when such information is graphically depicted in relation to a map or aerial photo image. Geo-referencing was the primary display mode for the iPad/Foreflight combination, and included terrain display and warning capability. The pilot reported that he used the iPad/Foreflight to determine his flight route. He was not specific about when or what method or information he used to determine the flight route. When asked, he reported that he did not enter or program any planned route into the device and that he did not have or use any paper charts before or during the flight. He reported that he used the iPad during the flight, but that it did not have the intended route of flight entered or displayed. The pilot wrote that he "entered the canyon with both sides of the canyon below me. The canyon walls rose to the ridge-line we were trying to fly over, but the [accident airplane] climb performance deteriorated to the point that it would not clear the terrain ahead. The ridge-line ahead was above me and I could clearly see this when entering the canyon without looking at the iPad. I judged we had enough distance ahead to climb over the ridge." Once he recognized that the airplane would not outclimb the terrain, the pilot executed a right turn to reverse course, but then stalled the airplane during that turn. In the "recommendation" section of the NTSB reporting form, the pilot wrote that one should enter a box canyon at an altitude above that of the canyon walls. He also stated that instruction in mountain flying could have aided in preventing this accident. Airplane Performance In communications with the NTSB, the pilot stated that he was unfamiliar with the airplane, particularly its climb performance, and that he incorrectly overestimated its actual climb capability. The kit manufacturer's Owner's Manual (OM) did not contain an Airplane Performance section. The only climb-related information in the OM was in the Normal Operating Procedures section, which presented the speeds for best angle of climb (75 mph) and best rate of climb (90 mph). The pilot did not report what speed he used in his attempt to climb above the terrain. The pilot stated that he was concerned by the fact that the engine was operating with cylinder head temperatures above 415°F, despite the fact that the previous owner told him that "the engine shop that built the engine assured him that was normal and not to worry." The investigation was unable to obtain any engine performance data to allow determination of the effect of the higher-than-expected CHT values on the airplane's climb capability. Based on the airplane empty weight, fuel load, and number of persons on board, the airplane weighed about 1,800 lbs at the time of the accident. The kit manufacturer specified a maximum gross weight of 1,960 lbs. Stalls Stall and stall speed information was presented in the Limitations and Normal Operating Procedures sections of the OM. No explicit stall speeds were published, and the airplane was not equipped with a stall warning system or an angle of attack indication system. Wings-level stall speeds for maximum gross weights were indirectly provided in the Limitations section via the kit manufacturer's designations of the bottoms of the white and green arcs on the airspeed indicator. The OM stated that the lower limit of the white arc (denoting the full-flap stall speed) was 49 mph, and the lower limit of the green arc (denoting the zero-flap stall speed) was 56 mph. The OM Limitations section stated that those values were derived from the kit manufacturer's test airplane. The OM then stated that, "Slight variations may be experienced in customer-built aircraft. Actual stall speeds should be determined from flight test of each individual aircraft, and the airspeed indicator markings should be adjusted appropriately." The OM was not annotated with any other stall speed information. NTSB personnel did not examine or document the wreckage, and the on-scene documentation of the wreckage by other personnel did not depict or note the actual airspeed indicator markings. The pilot reported that he had deployed two notches of flaps (not full) at an undetermined time just prior to or during the turn. The stall speed for that flap setting is unknown, but would be in the range between the zero-flaps and full-flaps stall speeds cited above. Stall speed varies directly with weight; decreased weight will decrease stall speed. Based on an estimated accident weight of 1,800 lbs, the wings-level stall speeds for the flight would have been about 2 mph less than the values in the OM. Stall speed also varies as a function of the bank angle; the stall speeds would have increased about 20 mph for this airplane in a 60° bank. The pilot did not report the speed at which he entered the course reversal turn or the bank angle or speed(s) he used in the turn. The Normal Operating Procedures section of the OM stated that, "power-on stalls tend to be more aggressive than power-off stalls. The stall has a more defined break, and the torque effects of the engine and propeller induce rolling and yawing forces…that make a wing drop more likely to occur. These yawing forces make the development of a stall into a spin more likely…however power-on stalls are still extremely predictable and controllable." The OM stated that the "break of a power-on stall is preceded by a significant amount of airframe buffeting, which provides a clear 3-5 kt. warning period before the onset of the stall." The pilot did not report whether he noticed any pre-stall buffet. Turn Radius and Mountain Flying The FAA publication Pilots Handbook of Aeronautical Knowledge states that turn radius is directly proportional to airspeed, and inversely proportional to bank angle. For a constant bank angle, turn radius increases with increased airspeed, and for a constant airspeed, turn radius decreases with increased bank angle. A minimum-radius turn would result from using the lowest airspeed and highest bank angle that still provide sufficient stall margin. Reduced stall speeds that result from flap extension can be used to reduce turn speed and resultant turn radius. Commercially-available mountain flying training guidance advocates that when flying into a canyon, winds and turbulence permitting, instead of flying near the center of canyon, the pilot should offset the flight path to the side. The purpose is to pre-position the airplane in order to provide the most terrain clearance in the event that a course reversal turn becomes necessary. The pilot did not specify the lateral position of the airplane in the canyon during the ingress, or any details of how he attempted to execute the course reversal turn.
The pilot's inadequate flight planning, preparation, and navigation, which resulted in the airplane entering a canyon that the pilot was unable to exit by climbing the airplane. Also causal were his in-flight decision-making and his execution of the course reversal turn, which resulted in an aerodynamic stall and terrain impact.
Source: NTSB Aviation Accident Database
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