MALAD CITY, ID, USA
N693PA
Mitsubishi MU-2B-36
A Mitsubishi MU-2 departed Salt Lake City, Utah, and climbed to 16,000 feet MS on an IFR flight to Pocatello, Idaho. While in cruise flight, the MU-2 encountered structural icing conditions. According to radar data, the MU-2 began slowing from a cruise speed of about 190 knots with slight deviations from heading and altitude. The airspeed decreased to about 100 knots, and the flight crew declared an unspecified emergency, then radio contact was lost. The MU-2 began a right turn, then it entered a steep descent and crashed. The pilot of a Beech 1900 (about 12 minutes in trail of the MU-2), stated that he encountered moderate rime icing at 16,000 feet. The Beech pilot activated his deice boots (3 times) and descended to 12,000 feet to exit the icing conditions. The MU-2 flight manual warned that during flight in icing conditions, stall warning devices may not be accurate and should not be relied upon; and to minimize ice accumulation, maintain a minimum cruise speed of 180 knots or exit the icing conditions. An investigation determined that the captain of the MU-2 was aware of deficiencies in the timer for the deice boots, as well as other maintenance deficiencies. The captain's medical certificate was dated 11/17/94; he was providing executive transportation for compensation under an agreement for "contractual flights," under 14 CFR 91. Although icing conditions were forecast in the destination area, no icing was forecast for the en route portion of the flight.
HISTORY OF FLIGHT On January 15, 1996, at 0618 mountain standard time (MST), a Mitsubishi MU-2B-36, N693PA, was destroyed when it impacted terrain in a near-vertical attitude approximately eight miles northwest of Malad City, Idaho. The crew had declared an unspecified emergency moments before while in cruise flight at 15,700 feet MSL (mean sea level). The airline transport pilot and commercial pilot crew members, and the six passengers on board, were fatally injured. The aircraft, owned by Pro Air Services of Utah, LLC (a Utah limited liability company), was being operated by Pro Air Services of Salt Lake, LLC, for the purpose of transporting Swire Coca Cola, USA, executives from Salt Lake City, Utah, the departure point, to Pocatello, Idaho. The flight was one of a series of demonstration flights for which Pro Air Services of Salt Lake received compensation exceeding that stipulated in 14 CFR Part 91. An instrument flight rules (IFR) flight plan was filed for the flight, which had departed Salt Lake City International airport at 0548:40. After departure from Salt Lake City, the aircraft had climbed to and leveled off at approximately 16,100 feet MSL and maintained about 190 knots indicated airspeed (KIAS for close to twelve minutes. The aircraft then performed a heading change of approximately 20 degrees to the east and a subsequent correction back to the original heading. An oscillatory descent to 15,700 feet MSL and a slow decrease in indicated airspeed to approximately 150 KIAS was noted from radar data over the next two minutes of flight following the initial change of heading. About 15 minutes after leveling off, at 0617, the crew advised Air Traffic Control (ATC) that they had an unspecified emergency. No further communications were made by the crew. Soon after that point, radar contact was lost. Radar data also showed the aircraft's indicated airspeed decreasing from about 190 knots indicated airspeed (KIAS) to about 100 knots (KIAS) in the six minutes immediately preceding the uncontrolled descent from 15,700 feet MSL. The wreckage was found in open hilly terrain, approximately 5240 feet MSL. There was no report of an ELT actuating. There was a post-crash fire. Before this flight, the MU-2's captain (who was a registered agent and officer of both Pro Air Service of Utah and Pro Air Services of Salt Lake) had previously provided at least 14 "executive demonstration" flights in N693PA to executives of Swire Coca-Cola, USA, while doing business as Pro Air Services of Salt Lake, LLC. The flight was conducted under 14 CFR 91, and was described as a series of flights for a "road show" marketing program for Swire Coca-Cola, USA, which is a large regional bottler of Coca-Cola products. Passengers on board the aircraft included four upper-level Swire executives, and two executives of Scopes Garcie Carlisle, Swire Coca Cola's advertising agency. No evidence was found that either Pro Air Services of Utah, LLC, or Pro Air Services of Salt Lake, LLC, held a 14 CFR 135 air carrier certificate. (The airplane was, however, on 14 CFR 135 operating specifications for D and D Aviation, LC, of Salt Lake City, which had an approved minimum equipment list for the aircraft.) A "flight management & consulting service agreement" existed between Swire Coca-Cola and Pro Air Services of Salt Lake, wherein a monthly stipend was paid by Swire Coca-Cola to Pro Air Services of Salt Lake, which would provide pilot services and management services, including making aircraft available which could be used for executive transportation. This agreement was signed August 1, 1995, and was to be valid for six months. A second agreement, also signed August 1, 1995, provided Swire Coca Cola with a list of aircraft "available for demonstration," with a price schedule based upon price per hour of utilization. On the morning of the accident, at 0516, the Cedar City (Utah) Automated Flight Service Station (AFSS), received a telephone call from the pilot of N693PA requesting a weather briefing and expressing a desire to file an IFR flight plan. That person stated that he planned on departing Salt Lake for Pocatello, Idaho, in about 20 minutes. The FSS specialist asked if the pilot wanted just current reports or a standard briefing. The pilot stated that current reports were okay," 'cause it doesn't take very long to get up there." The FSS specialist provided current Salt Lake City weather as "twenty thousand overcast, visibility ten, temperature thirty-one, dew point twenty-nine, winds calm. Pocatello is showing measured ceiling nine thousand overcast, visibility twenty, temperature forty-five, dew point twenty-one and the wind two-one zero at one three. [I] don't see any pilot reports and just to the northwest of Pocatello there is an airmet for occasional mountain obscuration right in the Pocatello area. To the north-northwest, northeast all the way around to the southwest, [an] airmet [exists] for occasional moderate rime icing from about six or ten thousand...somewhere between six and ten thousand feet all the way up to twenty thousand and then an airmet over Idaho for occasional moderate turbulence below sixteen thousand." The pilot requested winds aloft at 18,000 feet MSL, which the FSS specialist provided for Salt Lake City, from 260 degrees at 44 knots, and Pocatello, from 270 degrees at 49 knots. The pilot then filed an IFR flight plan, specifying that the aircraft had "slant romeo" equipment available (meaning that the aircraft was equipped with RNAV, or area navigation, with transponder and altitude reporting encoder), 260 knots cruise speed, departure time 1235 Zulu [0535 MST], 17,000 feet MSL cruising altitude, fifty minutes time en route direct from Salt Lake City to Pocatello. He stated that he had four hours of fuel on board, eight persons on board, and a black, silver and white aircraft. The conversation with the FSS specialist was terminated at 0519. The pilot did not file an alternate destination. According to IFR low altitude en route charts, the minimum en route altitude (MEA) for V-21, the airway that approximately underlies the proposed route of flight, was 10,000 feet MSL. Total distance was about 152 nautical miles. Pocatello VOR (a VHF omnigational range navigation facility) is 41 nautical miles from Malad City VOR; the crash site was approximately five miles north-northeast of Malad City VOR. Hudson General, an aircraft fueling facility at Salt Lake City International airport, fueled the airplane prior to the flight. Their invoice for Jet-A fuel, dated January 15, 1996, indicated that the four wing tanks were to be topped, and 45 gallons were to be pumped in each tip tank. Total fuel delivered to the aircraft was 138 gallons. Refueling personnel observed the passengers and crew boarding the flight, and provided a ground-power unit (GPU) start for the airplane. At 0542:33, the crew called Salt Lake City ATCT (Air Traffic Control Tower) ground control east by radio, advising that N693PA was at Hudson South and ready to taxi, and stated that they would "get their clearance on the way." At 0542:39, N693PA was cleared to taxi to runway 17. At 0542:56, Salt Lake City ATCT (Air Traffic Control Tower) clearance delivery was contacted by the crew of N693PA, who requested their IFR clearance to Pocatello. Clearance delivery provided an amended clearance to Pocatello, changing the pilots' filed routing to instead fly a heading of 160 degrees for a radar vector to V-21 to Malad, then direct to Pocatello; to climb and maintain eight thousand feet, and to expect 17,000 feet [MSL], ten minutes after departure. Departure control frequency of 135.5 Mhz (megahertz) and a transponder code of 4311 were also issued. The crew read back their clearance. Their altitude restrictions were clarified by clearance delivery. At 0543:56, the crew acknowledged the correct clearance to expect a climb to 17,000 feet [MSL] ten minutes after departure. At 0544:16, the crew of N693PA advised that they were back on ground control [frequency] after receiving their clearance. Ground control acknowledged. At 0548:28, the crew of N693PA contacted the control tower (Salt Lake City ATCT local control center) and advised that they were "ready to go" on runway 17. N693PA was cleared for takeoff at 0548:33. After departure, N693PA was given a right turn to a heading of 280 degrees and was told to contact departure control. The crew acknowledged at 0550:01. At 0550:06, the crew of N693PA contacted departure control (Salt Lake City TRACON). The controller advised that the airplane was in radar contact, and cleared N693PA to climb to and maintain 16,000 feet [MSL]. At 0551:34, departure control provided a right turn to 330 degrees, which was acknowledged. At 0552:30, departure control cleared N693PA to proceed direct to Pocatello, and advised the crew to resume their own navigation. This clearance was acknowledged. N693PA was then given a frequency change and hand-off to Salt Lake Center (Salt Lake City Air Route Traffic Control Center). The hand-off was acknowledged at 0554:36. At 0554:44, the crew of N693PA contacted Salt Lake Center and said they were "with you [at] ten-thousand five-hundred [feet MSL] for one-six thousand [feet MSL]." At 0554:52, Salt Lake Center acknowledged and cleared N693PA to continue climb to maintain [level off at] 17,000 feet MSL. The crew of N693PA requested a final altitude of 16,000 feet MSL, which was approved and acknowledged at 0555:07. According to radar data, N693PA continued climbing until it reached 16,000 feet at 0602:30. After some slight altitude and velocity variations while leveling off, N693PA maintained a steady altitude and flight path for approximately eight minutes. During this time, aircraft airspeed slightly varied, deviating about an approximate value of 190 knots (KIAS) and pitch remained essentially steady. From transponder radar data, a flight path heading deviation of about 20 degrees nose right occurred at approximately 0614:00, with a subsequent correction to the previous heading. This time also denotes the beginning of oscillations in altitude between 16,000 feet and 15,800 feet, which occur for the next two minutes. Calculated aircraft performance parameters during these oscillations show corresponding variations in airspeed, pitch attitude, and angle-of-attack. At 0615:51, the Salt Lake Center controller requested that the crew of N693PA change to his frequency of 128.35 Mhz. The crew of N693PA acknowledged the frequency change at 0615:56. Forty seconds later, at 0616:36, the crew of N693PA responded on the new frequency (with the same controller), stating that they were "with you [at] one-six thousand [feet MSL]." Altitude at that time, according to the altitude encoder radar data, was 15,800 feet MSL. The ATC controller acknowledged and provided the Pocatello barometric pressure of 30.06. At 0616:45, the crew of N693PA repeated the altimeter setting, stating "three zero zero six, thanks." Based upon radar transponder data, a decrease in airspeed of approximately 40 knots was observed between 0616:30 and 0617:30, along with analogous increases in pitch attitude and angle of attack. During this time, N693PA's altitude dropped to 15,700 feet MSL as the aircraft decelerated to about 150 knots (KIAS). A further reduction in airspeed is noted over the next 40 seconds to approximately 120 knots (KIAS), as the airplane varied its altitude first to 15,900 feet, then down to 15,700 feet MSL. About 0617:40, the final radar transponder altitude transmission was received, and a further decrease in airspeed to about 100 knots (KIAS) was observed; subsequent radar returns up to the end of the flight were primary radar returns only. At 0617:51, the crew of N693PA stated "center, uh Mitsubishi six niner three Papa Alpha we got an emergency." There were no further communications from N693PA, despite repeated attempts by Salt Lake Center to reestablish communications. Remaining primary radar returns indicate a rolling right turn as the aircraft further decelerated, followed by a rapid increase in airspeed as the aircraft pitch abruptly shifted to a steep nose-down attitude. The calculated parameters indicate a change in pitch attitude occurred near, or shortly after, the time the crew declared an emergency. The final radar returns are indicative of the airplane experiencing an uncontrolled high-speed descent in a steep nose-down attitude. The aircraft impacted hilly terrain at about 5240 feet MSL, in an attitude of approximately 105 degrees nose down. There were no eye-witnesses to the crash, however two ice fishermen heard the airplane prior to the crash. The ice fishermen, who were in a portable ice hut on St. John's Reservoir approximately 5.5 miles east of the crash site, heard the aircraft before and during its descent. After the impact, they looked outside and saw the glow of a fire, which they presumed to be the crash site. One fisherman described the conditions as dark night with a heavy cloud cover and no fog. He said that he heard the airplane about 0615, and noted that at about 0715 it started snowing. He said the noise came from the south for about a minute. Near the end, he said it went totally quiet, then the engines revved up. Then he heard the impact. The pilot of AMF624, a Beech 1900, which was approximately 12 minutes in trail of N693PA on the same route of flight, stated that he had encountered moderate rime icing while in cruise flight at 16,000 feet MSL about 20 miles east of Malad VOR. The rate of ice accumulation was about 1/4 to 1/2 inch per minute. Total ice accumulation on unprotected areas of the airframe was about one inch, and the aircraft remained in the icing environment for about five minutes. The pilot described the ice as appearing similar to "refrigerator ice with little fingers 1/2 to 1 inch long." The ice accumulated about five inches aft on the propeller spinner. AMF624's pilot also noted that the airplane experienced an approximate 10 to 15 knots loss of airspeed. Outside air temperature at 16,000 feet was about -12 degrees C. In the icing environment there was rain and snow mixed, with cloud bases about 12,000 feet and cloud tops about 18,000 feet. The pilot stated that he activated the deice boots three times, determined that he was in moderate rime ice and diverted to 12,000 feet, where most of the ice sublimated before reaching his Idaho Falls, Idaho, destination, northeast of Pocatello. Radar data indicates that AMF624 requested and initiated a descent from 16,000 feet MSL about 0629 (when about two miles west of the crash site). PERSONNEL INFORMATION The captain, male, age 48, listed his occupation as "aircraft sales" on his most recent airman's medical certificate application of November 17, 1994. He was self-employed, as manager and registered agent of Pro Air Services of Salt Lake, LLC (a Utah limited liability company formed April 12, 1993), and president and registered agent of Pro Air Services of Utah, LLC (which was also formed April 12, 1993). According to the Articles of Organization for both limited liability companies, the purpose of both companies was to be able to engage in any lawful business for which a company may be organized under the Utah Limited Liability Act, including but not limited to: Aircraft sales, servicing, leasing, consigning, purchasing and consulting; and to provide any and all services relating to the aircraft industry including sales, servicing, leasing, consigning, purchasing and consulting. The captain was issued a private pilot's certificate for single-engine land airplanes on February 28, 1971. On August 30, 1975, according to FAA records, he added a multi-engine land airplane rating, and had a total of 990 hours pilot-in-command flight time. On September 20, 1975, he added an instrument rating, with a total pilot-in-command flight time of 1006 hours. On January 23, 1977, he acquired a commercial pilot's certificate with single-engine land airplane rating and private pilot privileges in multi-engine land airplanes, before adding multi-engine land airplanes to his commerc
continued flight by the flightcrew into icing conditions with known faulty deice equipment; structural (airframe) ice; and failure of the flight crew to maintain adequate airspeed, which resulted in the loss of aircraft control and collision with terrain. A factor relating to the accident was: the en route weather (icing) condition, which was not forecast (inaccurate forecast).
Source: NTSB Aviation Accident Database
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