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On November 25, 1995, at 1554 mountain standard time, a Beech C24R, N3729T, registered to First National Insurance of Dillon, Montana, was substantially damaged when it collided with mountainous terrain approximately 13 nautical miles north-northeast of Gallatin Field, Bozeman, Montana. Both occupants (the private pilot and a passenger) were fatally injured. The 14 CFR 91 flight had originated at Troutdale, Oregon, with a stop in Lewiston, Idaho, and was on an instrument flight rules (IFR) flight plan from Lewiston to Bozeman. The flight had been cleared by Salt Lake Air Route Traffic Control Center (ARTCC) for an instrument landing system (ILS) approach to runway 12 at Bozeman. Instrument meteorological conditions prevailed in the accident area.
FAA air traffic control (ATC) records indicated that the pilot received a weather briefing from the automated flight service station (AFSS) at McMinnville, Oregon, and departed Troutdale on an IFR flight plan, landing at Lewiston and remaining on the ground there from 1232 to 1258 Pacific standard time. According to these records, the flight was cleared to an altitude of 13,000 feet out of Lewiston and cruised at an altitude between 11,000 and 13,000 feet for the entire flight from Lewiston, maintaining 13,000 feet for the last 32 minutes prior to arriving at THESE intersection (284 degrees magnetic/19 nautical miles from the Bozeman VOR/DME, an initial approach fix (IAF) for the ILS approach.) The aircraft was not equipped with cabin pressurization or supplemental oxygen. Communications transcripts documented a number of irregularities in the pilot's radio communications during flight at these altitudes, including incorrect altimeter setting readback (1429:41), confusing/stumbling over his call sign (1429:41 and 1514:33), stumbling over airway assignment/altitude options given by the controller (1508:10), and failing to respond to a frequency handoff call for over 30 seconds until the controller's third attempt at contact (1513:53 to 1514:27.) The communications transcript also indicated that at one point (1504:36), a Spokane approach controller, handing the flight off to Salt Lake ARTCC, relayed to the Salt Lake controller that the airplane was "a negative oxygen equipped" and gave the opinion that the pilot was "not all that good at navigating", and asked the Salt Lake controller to "make sure he comes our [sic] the other side." During this exchange, the pilot was maintaining an altitude block from 11,000 to 13,000 feet due to icing conditions at 11,000 feet, according to the transcript.
According to the FAA ATC records, the pilot approached THESE from the northwest along the V343 federal airway. He reported at THESE intersection and was cleared for the approach at approximately 1544. The last National Track Analysis Program (NTAP) recorded radar position on the aircraft was approximately 6 nautical miles west-northwest of THESE at 13,100 feet at 1541:25. According to the FAA ATC communications transcript, the Salt Lake ARTCC controller informed the pilot that radar contact had been lost at 1546:14.
The ILS runway 12 instrument approach procedure for Bozeman specifies that from THESE IAF, the approach is flown on the 060 degree radial outbound from the Whitehall VORTAC (approximately 43 nautical miles west of Bozeman) for 5.1 nautical miles at an altitude of 7,300 feet. A right turn is then made onto the localizer course of 118 degrees magnetic. According to the FAA ATC communication transcript, at 1546:24, the Salt Lake controller asked the pilot of N3729T if he was established on the localizer yet; the pilot replied that he was not. At 1549:41, the controller again asked the pilot if he was on the localizer yet. The pilot replied that he was not but that he expected to be established in "approximately four minutes." At 1555:54, the controller asked a third time if N3729T was on the localizer, this time without reply. A tape recording of 121.5 MHz from the Great Falls, Montana AFSS recorded an emergency locator transmitter (ELT) activation at 1553:50. This recording indicated that the source of the ELT signal was subsequently localized to a magnetic bearing between approximately 005 and 015 degrees from Gallatin Field. Several aircraft in flight also reported to the Salt Lake controller that they were receiving an ELT signal at this time.
A hunter in the mountains near the accident site observed a small single-engine aircraft flying "almost due east", 150 to 200 feet south of his position and at an altitude the hunter estimated to be 400 to 500 feet above him. He stated that it was snowing heavily at the time with a visibility he estimated at 400 to 500 feet. He stated that he observed the aircraft for about 10 seconds and that it appeared to be flying level or slightly climbing. He reported that 20 to 30 seconds after the airplane disappeared from view, he heard a loud metallic "clank." He stated that he checked his watch 15 to 20 seconds after hearing the noise and that his watch read 3:57 PM. He stated that the airplane's engine sounded like it was running smoothly during the time he observed the airplane.
The aircraft wreckage was located by an Air Force rescue helicopter on the morning of November 26. It was in mountainous terrain about 13.5 nautical miles north-northeast of Gallatin Field at approximately the 7,800 foot level on a 30 to 35 degree slope. Both occupants were subsequently found dead at the scene. The accident site was offset approximately 2 nautical miles to the right of the extended 060 degree radial of Whitehall VORTAC and was approximately 21 nautical miles east-northeast of THESE.
The accident occurred during the hours of daylight at 45 degrees 59.78 minutes North and 111 degrees 2.46 minutes West.
According to a copy of an FAA airman certificate application dated October 27, 1995, which was recovered from the aircraft wreckage, the pilot had approximately 150 hours total pilot time including 42 hours of instrument time and 1 hour on an AST-300 simulator. The FAA application indicated that the pilot had received his private pilot certificate on August 22, 1995. He successfully completed a practical test for an instrument rating in a PA-28-161 airplane at Billings, Montana, on October 28, 1995. The certificated flight instructor (CFI) who finished the accident pilot's instrument training in Bozeman stated to investigators during a post-accident interview on November 27, 1995 that the pilot had practiced the Bozeman ILS runway 12 approach from THESE several times during his instrument training, and characterized the pilot's performance and proficiency during instrument training as well above average. The FAA designated examiner who administered the instrument practical test to the accident pilot described the pilot's performance on the test as "above average proficiency...considering his level of experience" in a letter to the NTSB investigator dated December 6, 1995.
The CFI who had finished the accident pilot's instrument flight training stated that he had flown two checkout rides, totaling 2.3 hours, in the C24R with the accident pilot on the Monday and Tuesday before the accident (November 20 and 21) and that the pilot departed on a cross-country flight to Oregon in the C24R immediately afterward, on the afternoon of the 21st. The aircraft owner and the CFI both stated in post-accident interviews that they instructed the pilot not to fly the aircraft in instrument conditions. The aircraft owner repeated this statement in a written report of the accident, stating that he and the CFI agreed that this would be a condition of use of the aircraft for the accident pilot. The CFI stated during his interview that he provided only a basic aircraft checkout to the pilot, consisting of basic air work, emergency procedures and visual traffic patterns; and that he deliberately gave the pilot no instrument instruction in the C24R since he did not want the pilot to fly the aircraft on instruments.
Investigators did not locate logbooks for the pilot and were unable to determine whether he had a CFI logbook endorsement for high-performance aircraft per 14 CFR 61.31(e). The pilot's CFI in Bozeman stated that he did not endorse the pilot's logbook after the C24R checkout because he believed the pilot had previously received one, although he stated he did not personally verify that the pilot's logbook contained a previous high-performance aircraft endorsement. Inquiries to previous CFIs did not disclose evidence that the pilot possessed previous high-performance or complex aircraft experience. The CFI in Bozeman did state that during the C24R checkout flights, the accident pilot had, in the CFI's judgment, demonstrated satisfactory proficiency to operate safely as pilot-in-command of the C24R in visual meteorological conditions.
Aircraft navigational instrumentation included two VOR receivers (one ILS-capable); automatic direction finding (ADF) equipment; marker beacon receiver; and distance measuring equipment (DME). The aircraft logbook indicated that a standby vacuum system had also been installed.
The aircraft was also equipped with an Apollo 2001 Global Positioning System/Long Range Navigation (GPS/LORAN) receiver. The installation records in the aircraft logbook indicated that this system was certified for visual flight rules (VFR) operations only. A repairman from AeroTronics, Inc. of Billings, Montana, who performed the installation, stated to the investigator that there was no tie-in from the GPS/LORAN unit to the other aircraft instrumentation; i.e. the GPS/LORAN receiver functioned autonomously and did not provide navigation data to other aircraft instruments.
Maintenance records furnished by AeroTronics also indicated that the aircraft had failed its most recent static system test and that repair work on the aircraft static system was not yet completed. The AeroTronics work order indicated that the aircraft was certified for VFR flight only, due to not passing the static system test.
No evidence was found in the aircraft records to indicate that the VOR system checks for IFR flight had been performed per 14 CFR 91.171.
The FAA reported that the pilot obtained a weather briefing from McMinnville AFSS prior to departing Troutdale on the day of the accident, and was on an IFR flight plan under the control of Salt Lake ARTCC at the time of the accident. The 2256 UTC (1556 MST) Bozeman surface observation was: scattered clouds at 1,800 feet; measured overcast ceiling at 2,400 feet; visibility greater than 10 miles with light rain; temperature 39 degrees F; dewpoint 37 degrees F; wind from 100 degrees magnetic at 7 knots; and altimeter setting 29.88 inches Hg. An AIRMET meteorological advisory was in effect for IFR conditions and mountain obscuration in the area.
The hunter in the mountains near the accident site, who observed a small, eastbound single-engine airplane at approximately the time of the accident, stated that the weather in the accident area at the time consisted of heavy snow with an estimated visibility of 400 to 500 feet.
AIDS TO NAVIGATION
According to FAA airport and navigational aid data obtained through the Internet, the Bozeman runway 12 localizer course width is 3.71 degrees. Based on a width of 3.71 degrees, the localizer course width at FALIA (the localizer intercept point on the approach), which is 15.3 nautical miles from the runway threshold and 17.1 nautical miles from the localizer antenna per FAA data, is approximately 1.1 nautical miles.
The Jeppesen approach plate for the Bozeman ILS runway 12 approach identifies three radio navigation aids which may be used to determine that the localizer centerline is being crossed: the localizer signal itself, the MANNI compass locator beacon, and a DME indication of 32 nautical miles from Whitehall. The aircraft was equipped to receive all three of these navigation aids simultaneously. Frequencies extracted from the #1 (ILS-capable) NAV and ADF receivers in post-accident testing (see TESTS AND RESEARCH below) matched the Bozeman ILS and MANNI frequencies, respectively. The frequency extracted from the DME was 113.50 MHz as compared to Whitehall's frequency of 113.7 MHz.
The NTSB investigator-in-charge observed an ILS approach to Bozeman runway 12 from THESE IAF, flown in visual conditions, on November 27, 1995. Proper course and glide path indications and strong identification signals were observed from all navigational aids associated with the approach.
Salt Lake ARTCC voice recordings revealed three other aircraft which flew the ILS approach during the accident time frame: Northwest 1047; Pipestone 44; and N690BE. Pilots on all three flights stated via telephone that they did not observe any anomalies or experience any problems with the ILS navigational aids.
AERODROME AND GROUND FACILITIES
Gallatin Field does not have a control tower or terminal radar control (TRACON) facility. IFR flights into Bozeman are controlled by Salt Lake ARTCC.
The ILS approach procedure to Bozeman runway 12 specifies that from THESE IAF, the approach is flown outbound on the Whitehall 060 degree radial at 7,300 feet, turning right onto the localizer at FALIA. At 7,300 feet, approximately 15 1/2 nautical miles beyond FALIA, the Whitehall 060 degree radial intersects mountainous terrain in the vicinity of the accident site.
On-scene wreckage documentation was performed by rescue personnel from the Gallatin County Sheriff's Department on November 26, 1995. The sheriff's report indicated that the aircraft was discovered in an upright attitude, heading downhill on an estimated 30 to 35 degree slope. The fuselage heading was measured at 335 degrees "with declination." Both wings, both doors, and the engine cowl had separated from the aircraft with the left wing located just forward and to the left of the fuselage, and the right wing located under the empennage. The report indicated that "There was major damage to the front of the aircraft, with the propeller, a large part of the cowling, and other engine parts missing." The report indicated that "numerous items from the interior and exterior of the plane" along with the left door and engine cowl were found in an area about 40 feet uphill from the tail of the airplane. There was about 8 inches of fresh snow on the slope with an approximate 4 inch base. The rescuers used a GPS unit to record the crash site coordinates as 45 degrees 59.777 minutes North and 111 degrees 2.460 minutes West. A portable altimeter carried by the rescuers indicated the crash site elevation to be approximately 7,820 feet.
Investigators from the NTSB, FAA, Raytheon Aircraft, and Textron Lycoming examined the aircraft wreckage in further detail at Gallatin Field on December 14, 1995. During this examination, extensive damage was noted to the front end of the airplane while the fuselage aft of the cabin was substantially intact. The right side of the fuselage had a circumferential crack from top to bottom at the aft end of the cabin. The engine was in its mounts but was cocked 23 degrees right side up and 31 degrees forward end up. It was also laterally offset 6 1/2 inches left of the aircraft centerline at the forward end, and 18 inches left of centerline at the aft end of the engine. The aft end of the engine was in contact with the firewall. The engine crankshaft was fractured at the propeller mounting flange, and the propeller was separated from the engine with the mounting flange remaining bolted to the propeller hub. Both propeller blades were torsionally twisted; one blade exhibited "S" bending. A fuselage crush angle of 31 degrees was measured on the right side of the nose. Both wings were separated from the fuselage at the roots. The ailerons and flaps remained attached to the wings. The right wing exhibited leading edge damage for 65 1/2 inches inboard from the tip. There was a triangular impingement area into the right wing tip leading edge, with zero impingement at approximately 47 1/2 inches inboard from the wingtip line, increasing to a maximum impingement of approximately 32 inches back from the leading edge line at the wingtip. The left wing tip leading edge contained a smaller impingement area. The investigators discovered no evidence of flight control malfunction, engine malfunction, vacuum system failure, or fire.
Instruments examined at Gallatin Field included the ADF receiver and indicator, tachometer, omni-bearing selectors (OBS), turn coordinator, directional gyro, and the miniature "airplane" from the attitude indicator (the remainder of the instrument was missing.) The ADF frequency selector displayed 266, which matched the frequency of the MANNI compass locator beacon on the Bozeman ILS runway 12 approach. The ADF indicator was a rotatable card type. The bearing indicator was pointing to 075 degrees on the card, with the card being set to 357 degrees. The #1 OBS, which contained the ILS display, had been fragmented and only the bezel ring and a portion of a circuit card was found. The #2 OBS was set at 005 degrees with the #2 NAV frequency selector displaying "2.2" (the other numbers were not readable.) The 005 degree bearing setting approximately matched the radial of the accident site from the Bozeman VOR/DME, which operates on 112.2 MHz. White paint transfer was observed along the underside of the left wing of the attitude indicator "airplane." The tachometer indicated 2,250 RPM. The directional gyro indicated 205 degrees. The turn coordinator indicated a standard-rate right turn.
A loose Jeppesen approach plate for the Bozeman ILS runway 12 approach was found in the cabin. The approach plate was printed with terrain contour data on its plan view; however, the accident site was beyond the plan view area of coverage on the plate.
MEDICAL AND PATHOLOGICAL INFORMATION
An autopsy on the pilot was performed by the Gallatin County Medical Examiner's Office, Bozeman, on November 28, 1995. Toxicology testing on the pilot was performed by the FAA Civil Aeromedical Institute, Oklahoma City, Oklahoma. The toxicology tests screened for carboxyhemoglobin, cyanide, ethanol and drugs and did not detect any of these substances.
The text "Basic Flight Physiology" (TAB Books, 1992) by Richard O. Reinhart, M.D., a FAA senior aviation medical examiner and U.S. Air Force flight surgeon, states: "...the lack of adequate oxygen in the body's metabolism is called hypoxia....At 12,000 to 15,000 feet the effects of hypoxia on the nervous system can become increasingly incapacitating....As time at this altitude continues (as little as 10-15 minutes), impaired skills are very evident....frequent subtle errors in flying skills become apparent....If supplemental oxygen is not available, then getting the airplane or cabin altitude below 10,000 feet is mandatory." The text lists 22 common symptoms of hypoxia, one of which is given as "Stammering, can't get the right words out to ATC."
Per 14 CFR 91.211(a)(1), for flights at cabin pressure altitudes above 12,500 feet above mean sea level (MSL) up to and including 14,000 feet above MSL, the required minimum flight crew must be provided with, and use, supplemental oxygen "for that part of the flight at those altitudes that is of over 30 minutes duration."
Following receipt of the ELT signal and loss of contact with the airplane on the afternoon of the 25th, a search and rescue operation was initiated. Rescuers were able to determine the general location of the ELT signal source on the 25th; the wreckage was located by a U.S. Air Force rescue helicopter on the morning of the 26th. Both occupants were found dead at the scene by rescuers.
According to the county sheriff's report, rescue personnel found the pilot outside the aircraft at the scene. The report stated that the pilot's seat belt was found buckled, but that the lower left seat belt attachment to the fuselage had separated.
TESTS AND RESEARCH
Several avionics components were forwarded to AlliedSignal General Aviation Avionics of Olathe, Kansas, the manufacturer of the components, via the FAA manufacturing inspection district office (MIDO) in Kansas City, Missouri, for further evaluation. AlliedSignal determined that the #1 NAV receiver (the ILS-capable receiver) was tuned to 109.3 MHz, which matched the ILS frequency at Bozeman, and that the #1 NAV receiver operated satisfactorily during a functional check. Their examination also revealed that the #2 NAV receiver was tuned to 112.2 MHz, which matched the frequency of the Bozeman VOR/DME. The #2 NAV receiver was reported functional but with bad sensitivity. The DME frequency indicated 113.50 MHz. The ADF receiver switch was in the "on ADF" position and the ADF sensitivity and receiver were reported to function satisfactorily. The ADF indicator and both OBSs were determined to be too badly damaged to test.
The GPS receiver, LORAN receiver, GPS control unit, and GPS altitude encoder were forwarded to II Morrow, Inc. of Salem, Oregon, the manufacturer of the system, via the FAA flight standards district office at Hillsboro, Oregon, for further evaluation. II Morrow determined that the GPS and LORAN units functioned satisfactorily in functional testing, that the unit's switch was in the ON position, and that GPS had been selected. A present position of 45 degrees 59.88 minutes North, 111 degrees 2.71 minutes West was extracted from the GPS unit. This position was within approximately 1/4 mile of the crash site coordinates recorded by the rescue team's GPS. The unit was reported to have Whitehall set as its active waypoint.
Based on a straight-line distance of 21 nautical miles from THESE to the accident site, altitude loss of 5,280 feet (13,100 feet at THESE and 7,820 feet at the accident site) and 10 minutes from THESE to ELT activation (1544 to 1554), the average ground speed and descent rate from THESE to the accident site were computed to be 126 knots and 528 feet per minute, respectively. An airplane traveling at this average ground speed and descent rate, flying in a straight line from THESE to the accident site, will pass FALIA (the localizer intercept point, 5.1 nautical miles past THESE) at an altitude of 11,818 feet, approximately 2.4 minutes after departing THESE; and will descend through 10,000 feet about 12.3 nautical miles/5.9 minutes past THESE (7.2 nautical miles/3.5 minutes after passing FALIA and 4.1 minutes prior to ground impact.) Based on a localizer course width of 3.71 degrees/1.1 nautical miles (see AIDS TO NAVIGATION above) and a localizer course of 118 degrees magnetic, an airplane flying a constant magnetic track of 060 degrees through FALIA at a ground speed of 126 knots will transit the full width of the localizer course (from full left to full right course deviation indicator deflection per FAA Advisory Circular 61-27C, Instrument Flying Handbook) in 37 seconds.
The aircraft wreckage was released to Mr. Myron Carlson of COMAV Managers, Inc., Northglenn, Colorado, on July 19, 1996. Mr. Carlson is the insurance adjuster representing the aircraft owner. A copy of a letter from Mr. Carlson to the aircraft owner, which Mr. Carlson forwarded to the NTSB, indicated that Mr. Carlson had forwarded the NTSB Form 6120.15, Release of Aircraft Wreckage, to the aircraft owner's attorney for the aircraft owner's signature. As of the date this report was submitted, the signed wreckage release form had not been returned by the aircraft owner.
Additional Persons Participating in this Investigation (continued):
Timothy L. Mintzer II Morrow, Inc. Salem, OR 97309