SEA98FA078

The flight was on a practice nondirectional beacon (NDB) approach to Great Falls runway 34 in visual conditions. Abeam the final approach fix, the aircraft was 4 miles right of course. Upon being advised of this by ATC, the pilot corrected back to final with a 60-degree intercept angle, rolling out on course 3 miles from the runway. When the pilot called missed approach, the local controller (a trainee) instructed the pilot to make a 360-degree right turn to enter right downwind for runway 3, and the pilot acknowledged. The controller trainee then amended this instruction to a 180-degree right turn to enter right downwind for runway 21, then to a 180-degree right turn to enter right downwind for runway 3. The crew did not acknowledge the amended instruction. Controllers then observed the airplane had crashed. Witnesses reported the airplane entered a steep descent from a right turn and impacted the ground at a steep angle. The flight was described as recurrent training required by the owner's insurance; however, the second aircraft occupant's airline transport pilot and flight instructor certificates had been revoked, and he held only a private pilot certificate. Investigators found no evidence of aircraft malfunctions.

History of flight

On May 19, 1998, approximately 1536 mountain daylight time, a Piper PA-31T1 Cheyenne I airplane, N121BE, was observed to enter a steep descent and impact terrain approximately 1/2 mile south of the Great Falls International Airport, Great Falls, Montana. The airplane was destroyed by impact forces and a post-crash fire, and both of the airplane's occupants (consisting of an airline transport pilot, who owned the airplane, and a multiengine and instrument-rated private pilot who was a former airline transport pilot and certificated flight instructor) were fatally injured. It could not be determined which of the aircraft occupants was acting as pilot-in-command of the flight. The 14 CFR 91 local flight was described as an annual recurrent training flight required for the aircraft owner's insurance policy; however, due to the lack of an authorized instructor aboard the aircraft, the operation did not meet the FAA's definition of "flight training" as given in 14 CFR 61.1. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed for the flight.

According to FAA air traffic control (ATC) information, the airplane took off from Great Falls under visual flight rules (VFR) approximately 40 minutes before the accident, with the intention of performing air work and practice instrument approaches. After taking off from Great Falls runway 21, the pilot was given radar vectors to intercept the 11-DME (distance measuring equipment) arc for the Great Falls runway 3 instrument landing system (ILS) approach. Transitioning to ILS final from the 11-DME arc, N121BE flew the runway 3 ILS approach to a missed approach.

After starting the missed approach, the flight was cleared direct to the TRULY nondirectional beacon (NDB) to hold, and was instructed to maintain visual flight rules at a hard altitude of 6,500 feet (a military helicopter, BLADE 00, was holding at the nearby Great Falls VORTAC at 7,000 feet at that time, and ATC called this traffic out to N121BE.) The crew of N121BE acknowledged these instructions and stated they were looking for the helicopter. At 1515:44, the Great Falls approach controller again instructed N121BE to maintain 6,500 feet and maintain VFR. In a written statement, the approach controller on duty at the time indicated that he transmitted this instruction because of deviations by N121BE from its assigned altitude. ATC communications transcripts indicated that during an approach controller position changeover briefing at 1517:37, while N121BE was in holding at TRULY, the offgoing approach controller advised the oncoming approach controller: "...watch him he's been all over the altitudes sixty one hundred to sixty seven hundred so you might want to keep an eye on that...."

At approximately 1528, N121BE requested to start outbound for the procedure turn for the NDB runway 34 approach to Great Falls. ATC cleared the pilot for the NDB runway 34 approach and instructed him to maintain VFR. The approach controller also advised N121BE that ATC may have to break the aircraft out prior to the runway 34 approach end due to a formation of F-16 military fighter aircraft recovering from the north. The approach controller then queried the pilot of N121BE regarding his intentions following the NDB approach, and the pilot replied that he wanted to circle to land on runway 3 out of the approach. N121BE was subsequently handed off to the Great Falls local controller at 1532:46.

National Track Analysis Program (NTAP) ATC radar data furnished by the FAA indicated that on the NDB runway 34 approach, N121BE failed to achieve proper course alignment at the final approach fix (TRULY NDB). At the time the aircraft passed abeam TRULY, approximately 1533:03, it was approximately 4 miles right of course. At 1533:09, the Great Falls local controller advised the pilot of N121BE that the aircraft appeared to be well right of the final approach course, and the crew of N121BE replied that they were correcting. NTAP radar data indicated that the aircraft then turned left to intercept the published final approach course at an approximately 60-degree intercept angle. The aircraft subsequently turned right and rolled out on the final approach course at 1535:03, at a point approximately 3 miles south of the runway 34 threshold. The last NTAP radar position recorded on the aircraft was at 1536:03, approximately 3/4 mile south of the runway 34 threshold, at 4,400 feet (726 feet above the airport elevation of 3,674 feet.) The average point-to-point ground speed and vertical velocity between the last two NTAP positions (i.e. from 1535:51 to 1536:03) were computed to be 114 knots and 500 feet per minute down, respectively.

At 1535:45, N121BE called missed approach. According to NTAP radar data, the aircraft was approximately on course, between 1 and 1 1/2 miles from the threshold, at this time. The Great Falls local controller, who indicated in a written statement he was working the position at that time as a "developmental", instructed N121BE to "make a right three sixty enter the right downwind runway three." N121BE replied, "and we'll do a right three sixty for one bravo echo." This reply, at 1535:53, was the last radio transmission received from the accident aircraft. At 1536:08, the local controller transmitted: "cheyene [sic] one bravo echo make that a right one eighty enter the right the right [sic] downwind runway two one traffic two [F-16s] correction enter the right downwind runway three traffic two [F-16s] straight in three miles." N121BE did not reply to this instruction, and the local controller subsequently made two unsuccessful attempts to contact N121BE on the radio, at 1536:36 and again at 1536:41. At 1536:44, the Great Falls tower controllers observed that N121BE had crashed. The crash site was approximately 0.9 mile southeast of the runway 34 threshold and approximately 1/2 mile east of the last NTAP radar position.

The crash was witnessed by several individuals, with nine persons providing statements to NTSB or FAA investigators. Of the nine witnesses, two witnesses reported that prior to impact, the airplane appeared to be flying at a slow speed, and three reported that prior to impact they observed the airplane's wings rocking back and forth. The majority of witnesses reported seeing the airplane in a turn or bank prior to its nose dropping (the direction of turn varied among the witnesses), with three reporting the turn or bank as slight and two reporting it as hard or steep prior to the nose drop. Additionally, three witnesses reported they saw the airplane "spiraling" (describing a rolling motion) to the right before ground impact. Most witnesses also reported observing the airplane in a steep nose-low descent, with three further reporting that the aircraft impacted at a steep nose-low angle estimated variously between 30 and 80 degrees nose-down. Three witnesses reported that the aircraft appeared to momentarily regain (or begin to regain) control immediately prior to ground impact. The majority of witnesses reported that the aircraft burst into flames at impact, with four witnesses reporting they observed no fire or smoke before impact and no witnesses reporting observing any fire or smoke prior to ground impact.

Three of the nine witnesses reported hearing abnormal engine sounds (sputtering, cutting out, or a "waah...waah...waah" sound) prior to ground impact, and one witness reported that the engine or engines seemed to be at full power before impact (although this witness also stated he could not tell whether or not both engines were running at the time.) The remaining five witnesses either did not report any observations regarding engine operation prior to impact, or stated they were unable to tell whether or not the engines were operating during the accident sequence.

The accident occurred during the hours of daylight at 47 d