Burlington, VT, USA
N26399
Piper PA-23-250
While flying the ILS approach to the destination airport, the airplane remained aligned (laterally) with the inbound approach course; however, it remained above the glideslope, and then descended through it, approximately 7 miles from the runway. The airplane continued a gradual descent until it impacted wooded terrain approximately 3 miles from the approach end of the runway. Examination of the airplane revealed no mechanical deficiencies. The airport was equipped with a Minimum Safe Altitude Warning System (MSAW) designed to alert controllers when an aircraft is in danger of colliding with terrain or obstructions. Examination of system documentation and the radar replay revealed a low-altitude alert was displayed on the radar screen, and an alert message was sent to activate the MSAW alarms. Although the approach controller had transferred control of the airplane to the local controller, he continued to monitor the airplane on the approach. When he noticed the airplane descend below the glidepath, he notified the local controller, whose radar display also indicated a low altitude alert; however, the local controller's first instruction to the pilot to "climb," was 5 seconds after the last target was observed on radar. The pilot reported 470 total hours of flight experience, and 92 hours of total (actual) instrument flight time. During the preceding 6 months, the pilot accumulated 2 hours of instrument flight time.
HISTORY OF FLIGHT On November 22, 2005, about 1845 eastern standard time, a Piper PA-23-250, N26399, was substantially damaged when it impacted terrain during an instrument approach to Burlington International Airport (BTV), Burlington, Vermont. The certificated commercial pilot was fatally injured. Night instrument meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan was filed for the flight. The personal flight, which originated at Hartford-Brainard Airport (HFD), Hartford, Connecticut, at 1730, was conducted under 14 CFR Part 91. According to recorded communication between the pilot and Burlington Air Traffic Control (ATC), the pilot made initial contact with the Arrival Controller (AR) at 1822:15, and advised he was at 7,000 feet. The AR issued the pilot vectors for the ILS RWY 33 approach, and at 1834:34, the AR controller instructed the pilot to fly heading 350 to join the localizer. Five seconds later, the AR controller said, "Aztec 399 you're three miles from NIDUQ [final approach fix], maintain 5,400 [feet] until crossing NIDUQ, cleared ILS/DME 33 approach." The pilot acknowledged the clearance. At 1839:25, the AR controller instructed the pilot to contact Burlington tower and the pilot acknowledged. At 1839:42, the pilot made initial contact with the BTV local controller (LC) who said, "Continue, wind 360 at 20, braking action reported poor recently by an Embraer." The pilot acknowledged. At 1841:24, the LC controller told the pilot that he was cleared to land on runway 33, and the pilot acknowledged. At the same time, the AR controller was also monitoring the pilot on the approach, and at 1843:58, the AR controller called the ground controller (GC), (mistakenly instead of the LC), and stated, "hey that Aztec is a little low on the approach there." At 1844:14, the AR controller called the LC controller over the landline and advised, "that guy's too low out there." At 1844:15, the LC controller said, "Aztec 399 low altitude alert ah climb immediately maintain 2,000 [feet]." At 1844:23, the LC controller again transmitted to N26399 but received no response. There were no further communications with the pilot. According to radar data provided by the Federal Aviation Administration (FAA), the airplane remained aligned with the inbound approach course, on a track of 330-degrees; however, the airplane remained above the glideslope on the approach, and then descended through it, approximately 7 miles from the runway. The airplane continued a gradual descent until the last radar target was observed at 1844:10, at an altitude of 900 feet, approximately 3 miles from the approach end of runway 33. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with ratings for airplane single-engine land, airplane multi-engine land, and instrument airplane. His most recent FAA second-class medical was issued on April 27, 2004, with no restrictions. At that time, he reported 470 hours of total flight experience. Examination of the pilot's logbook revealed the last entry was for an instrument flight from HFD to BTV on October 7, 2005. According to the logbook, the pilot had accumulated 479 hours of total flight experience, 16.4 hours of which were in the preceding 12 months. The pilot also recorded 92.7 hours of total (actual) instrument flight experience, 10.7 hours of which were in the preceding 12 months, and 1.9 hours of which were in the preceding 6 months. The pilot's most recent flight review, and an instrument proficiency check, were completed on July 27, 2005. AIRCRAFT INFORMATION The most recent annual inspection was completed on March 28, 2005, with no anomalies noted. METEOROLOGICAL INFORMATION Weather reported about the time of the accident, at BTV, included winds from 310 degrees at 14 knots, gusting to 21 knots, visibility 1 statute mile in light snow and mist, a broken cloud layer at 900 feet, an overcast cloud layer at 1,600 feet, temperature 30 degrees Fahrenheit, dew point 28 degrees Fahrenheit, and an altimeter setting of 29.13 inches of mercury. According to information provided by the FAA, the pilot contacted Bridgeport, Connecticut (BDR) Flight Service Station (FSS) at 0625, on the day of the accident, and requested an outlook briefing for a flight from HFD to BTV (at 1800), and a return flight. The weather forecasted for the flight included AIRMETs for turbulence, icing, and wind shear. The weather conditions expected at HFD at the time of departure included winds from 310 degrees at 19 knots, gusting to 35 knots, visibility greater than 6 statute miles, with light rain and broken ceilings, about 2,500 feet. The weather conditions expected at BTV at the time of arrival included northwesterly winds at 15 knots, gusting to 28 knots, 3 miles visibility with light snow and mist, and ceilings 2,500 feet. Occasional diminishing visibilities to 3/4 mile, with light blowing snow and overcast ceilings of 800 feet also forecasted. The pilot called the BDR FSS a second time, at 1614, and requested a "full IFR briefing" for a flight departing at 1730, from HFD to BTV, and a return flight from BTV to HFD. The forecast for HFD and BTV including the same information as his previous briefing. He then filed two IFR flight plans for the outbound and return flights. AIDS TO NAVIGATION Review of the ILS RWY 33 instrument approach procedure revealed that the inbound course was 326 degrees. The approach featured numerous step down fixes that required an aircraft to maintain minimum altitudes along segments of the approach. The minimum descent altitude was 535 feet msl (200 feet agl), and required 3/4 statute miles of in-flight visibility. The airport elevation at BTV was 335 feet msl. The FAA performed a flight check of the ILS RWY 33 approach at BTV, following the accident. No deficiencies were noted with the approach. AIR TRAFFIC CONTROL INFORMATION BTV is equipped with a Minimum Safe Altitude Warning System (MSAW) designed to alert controllers when an aircraft is in danger of colliding with terrain or obstructions. According to FAA MSAW documentation, two consecutive predicted alerts will initiate an MSAW warning to the controller working the affected aircraft. This alert consists of a five second beeping alert tone at the affected facility as well as a flashing green (the letters "LA") low altitude alert above the aircraft's data block that continues until the alert terminates. An ATC group was formed by the Safety Board, in part, to examine the operation of the MSAW system. According to the ATC Group Chairman's Factual Report: The BTV Automatic Radar Terminal System (ARTS) data print out indicated a message was sent at 1843:30 to the ARTS System Monitor console (SMC) computer to activate the MSAW alarms. This alert should have caused a 5 second aural and visual alert on the BTV tower radar display beginning at 1843:35, along with a flashing green "LA" in N26399's data block from 1843:35 until about 1844:05. According to the radar replay data, the aircraft then descended below radar coverage, the track went into coast status, and the alert terminated at 1844:10. According to the LC and AR controllers, they did not recall receiving an MSAW alert on the accident airplane; however, when they reviewed the radar replay they did observe an "LA" (low-altitude alert) for the accident airplane. Although the AR controller had transferred control of the airplane to the LC, he continued to monitor the airplane's position on the approach. He noticed that the airplane descended below the glidepath, and notified the LC. The LC then instructed the airplane to climb, but received no response. WRECKAGE AND IMPACT INFORMATION According to an FAA inspector who responded to the accident site, the airplane impacted 30-foot-tall trees, at a height of about 20 feet. Examination of the airplane, and corresponding tree markings, revealed the airplane impacted the trees in a "straight-and-level" attitude. The airplane then descended into upsloping terrain and came to rest in a field, approximately 300 feet from the initial impact point. The wreckage path was oriented on an approximate heading of 330 degrees. The airplane was recovered from the accident site, and further examined by a Safety Board investigator. Examination of the airplane revealed both wings were separated into several sections. The leading edges of both wings contained vertically oriented, circular concave impressions. The inboard section of the right wing remained attached to the fuselage, and fire damage was noted on the outboard portion of the attached wing section. All flight controls were accounted for, and flight control continuity was confirmed. The landing gear was in the extended position, and the flaps were also extended approximately 10-15 degrees. Examination of the throttle column revealed both throttle and propeller levers were in the full forward position, the left mixture lever was in the full forward position, and the right mixture lever was in the idle/cut-off position; however, impact damage was noted to the column. The altimeter displayed 2,920 feet, with the Kollsman window set to 29.12 inches of mercury. The left and right engines were rotated by hand at their respective propeller flanges. Valve train and crankshaft continuity was confirmed to the rear accessory drive on both engines. Thumb compression and suction was obtained on all cylinders, except the number one and number six cylinders on the left engine. Impact damage was noted on these cylinders. The magnetos from both engines were tested, and produced spark at all terminal leads. Examination of the top and bottom spark plugs, on both engines, revealed their electrodes were intact and light gray in color. Both propellers remained attached to the engines, and exhibited S-bending, and chordwise scratching. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot, on November 23, 2005, by the Office of the Chief Medical Examiner, Burlington, Vermont. The FAA Toxicology and Accident Research Laboratory, Oklahoma City, Oklahoma conducted toxicological testing on the pilot. TESTS AND RESEARCH The Kollsman altimeter was retained and a detailed examination was conducted at the manufacturer, under the supervision of the FAA. The examination revealed no pre-impact mechanical anomalies. ADDITIONAL INFORMATION The airplane was released to a representative of the owner's insurance company on December 7, 2005.
The pilot's failure to follow the published instrument flight procedure, which resulted in an in-flight collision with terrain. Factors in the accident were the local air traffic controller's inadequate monitoring of the MSAW system, and his delayed instructions for the pilot to gain altitude.
Source: NTSB Aviation Accident Database
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