# NTSB DEN01FA044: Aero Vodochody Aero. Works L-39CT, N602MC, Watkins, CO, January 24, 2001 - Type: NTSB accident investigation - Classification: Accident · Fatal · Field investigation · Final report - Date: January 24, 2001, 11:27 local (18:27 UTC) - Place: Watkins, CO - Coordinates: 39.762222, -104.57917 - Nearby events: https://openairdocs.org/map.md?lat=39.7622&lon=-104.5792&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: Fatal - Injuries: 2 fatal - Status: Completed, report July 15, 2002 - Report: Approved by Office Director - NTSB case key (mKey): 51387 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN01FA044 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/51387/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=51387 - Page: https://openairdocs.org/ntsb/DEN01FA044 ## Probable cause The pilot's failure to maintain aircraft control, and the subsequent inadvertent stall/mush. Factors were the pilot's diverted attention due to the failure of the rear canopy's acrylic transparency and the loss of communication with his back seat passenger, the pilot's lack of recent experience in make/model airplane, the airplane's improper aft weight distribution (center of gravity), and the pilot's fatigue (circadian rhythm). ## Analysis The pilot departed from runway 26 in the military jet trainer and made an immediate steep left hand turn at an estimated 100 to 300 feet above the ground. Approximately 30 seconds later, the back seat canopy transparency failed and separated from the aircraft. The back seat passenger's headset and hat accompanied the transparency fragments to the ground. The airplane began oscillating divergently, pitching up to near vertical, turned right, and impacted the ground longitudinally oriented approximately 60 degrees to the right of the energy track alignment. The airplane's most recent empty weight CG calculations indicate that the airplane was at 34.98% MAC; the factory recommends a 27.7% MAC empty weight CG. The airplane's flight CG (with two occupants and the main fuel tank full) was calculated to be 29.58% MAC. The manufacturer recommends an approximate flight CG of 23 to 25.5% MAC. As the CG moves aft of this envelope, aircraft control becomes progressively more sensitive. The manufacturer reported that their test pilot's have flown the airplane with CGs as high 34% to 35% MAC, and aircraft records indicate that the pilot had previous flight experience with CGs in the 29% to 30% MAC range. Aircraft records also indicate that the pilot had 38.6 hours of flight experience in the airplane in approximately 3 years, and 6.6 hours of experience during the last 18 months. The night before the accident, the pilot had returned from a trip around the world in his Boeing Business Jet, with multiple business stops along the way. Analysis of the rear canopy's transparency indicated that it was embrittled. ## Factual narrative HISTORY OF FLIGHT On January 24, 2001, at 1127 mountain standard time, an Aero Vodochody L-39CT, N602MC, was destroyed when it impacted terrain while on departure from Front Range Airport, Watkins, Colorado. The airline transport pilot and his passenger were fatally injured. MAC Flightlease, Inc., of Portland, Oregon, was operating the airplane under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the local flight that was originating at the time of the accident. No flight plan had been filed. According to airport personnel, on the morning of the accident, the airplane was topped off with 135 gallons of jet fuel. The tip tanks were not fueled, and an employee of the pilot said that the pilot always flew with them empty. Several witnesses observed the airplane taxi to runway 26 for departure (a tail wind departure). A pilot, in his airplane on the run up pad for runway 26, observed the accident airplane begin its takeoff roll while there was a Cessna 172 (possibly a 182) over the numbers on the departure end of the runway. A pilot in a Cessna 182, who was on 3/4 to 1 mile final when the accident airplane took the active runway, said she was surprised to see the jet on the runway in front of her. She didn't hear any radio calls from him to indicate that he was taking the active runway for departure. She said that she had to slow down and do a couple of "S" turns to allow for spacing. Another witness said that the accident airplane lifted off after a ground roll about 3,800 to 4,000 feet, but appeared to be flying really slow. Several witnesses observed the airplane make a sharp left turn, at approximately 100 to 300 feet above the ground, just past the end of the runway. Another pilot observed the accident airplane taking off and thought it was "very low" and then observed it make a sharp left turn (estimated to be 70 to 90 degrees of bank). He said he could see the whole top of the airplane in the turn. Another pilot said that the Cessna in front of the jet was flying its crosswind leg when the accident airplane began its turn over the departure end of runway 26. One pilot said that she heard no radio transmissions from the accident airplane through his entire departure sequence from Front Range Airport. Federal Aviation Administration (FAA) radar data indicates that at 1126:19, the airplane crossed the departure end of runway 26 at approximately 173 knots. At 1126:33, the airplane was turning southbound, and had lost an estimated 15 knots of airspeed. No altitude information could be retrieved from the radar data because the airplane's transponder was not emanating any signals. Approximately 2 nautical miles (nm) south of runway 26, the last raw radar return was recorded at 1126:56; the accident airplane's airspeed was estimated to be 200 knots. A witness, driving south on Imboden Road, reported seeing a cloud of debris depart aft of the airplane, and flutter in the sunlight to the ground. She said it looked like the airplane was discharging trash. She said the airplane suddenly nosed down and headed straight for the ground. A pilot driving north on Imboden Road said he saw the airplane fly nearly straight at him at approximately 300 feet. He said the airplane rolled left, and went straight down. A retired airline mechanic also driving north on Imboden Road said he estimated that the airplane was 400 feet above the ground and flying straight at him. He said that it was moving up and down "very quickly, in a real quick jerky manner [short frequent longitudinal oscillations]." A pilot flying approximately 1.5 nm behind the accident airplane said that she observed the jet to enter a very slight left bank, and climb slightly. Suddenly, she saw the jet's nose "go straight vertical," as if entering an aerobatic maneuver. The pilot then observed the jet nose-over to the right (west) and impact the ground. A witness standing outside of his home said he saw the airplane's right wing suddenly drop, and the airplane nosed down approximately 45 degrees. He said that there was never any discernible change in its engine noise. The witness said the airplane appeared to be flattening its dive and may have rotated slightly clockwise before disappearing from sight. The first police and fire/rescue personnel arrived on the scene at approximately 1140. PERSONNEL INFORMATION According to FAA records, the pilot received his airline transport pilot certificate on August 30, 1999; he was also a certificated flight instructor and ground instructor. On his last FAA flight medical application dated July 26, 2000, he reported that he had 5,100 hours of flight experience with 250 hours during the previous 6 months. The pilot reported on his last insurance application, dated August 27, 2000, that he had successfully completed a flight review and instrument competency check on August 15, 2000. The pilot flew his first demonstration flight in the airplane on October 21, 1997, then purchased it and registered it with the FAA on December 16, 1997. During the months of March and April of 1998, he received 13 hours of ground school and 11 hours of flight training in the airplane . On April 17, 1998, a Letter of Authorization (LOA) was issued to the pilot by the FAA; it was good through April 30, 2000. The only flight limitation of his LOA was that he could not fly in formation with another airplane. The letter also required the pilot to make at least three takeoffs and landings in this model airplane within the preceding 6 calendar months, or the privileges of the LOA were rescinded. On July 15 and 16, 2000, the pilot received an estimated 2 hours of ground instruction and two flights in the airplane with an instructor for a total of 2.3 hours. The FAA issued the pilot a new LOA which was good through July 31, 2002. A pilot flight logbook, documenting the pilot's L-39 flight time could not be found. The pilot reported on the airplane's insurance application, dated August 2000, that he had 150 hours in L-39s. His L-39 flight instructor estimated that the pilot had between 40 to 50 hours of L-39 flight experience. Maintenance logbooks, an aircraft flight log tracking sheet, and statements from other L-39 pilots suggest that the pilot had a total 38.6 hours of L-39 flight experience and 6.6 hours during the last 18 months. An employee of the pilot said the pilot flew to Washington D.C. in his Boeing Business Jet (BBJ) for the Presidential inauguration and associated events on January 20, 2001. On January 21 and 22, he flew (with three other crew members) to Europe and on to Shang hai, China, with stops at several locations for business meetings. On January 23, he was in Seattle, Washington, for a 5 hour meeting, and then flew home to Denver that evening. The next morning he flew the accident flight with the L-39. AIRCRAFT INFORMATION The airplane was a Czech Republic military single engine, turbofan (jet) trainer, two seat tandem airplane (39.8 feet in length; 31 feet total wing span), which was manufactured by the Aero Vodochody Company in 1991 (approximately 3,000 were built). It was never delivered to the original buyer, and was refurbished and recertified in 1996. It was powered by an AI-25TL turbofan engine which had two shafts, by-pass flow, 12-stages of compressor, annular combustion chamber, three stages of gas turbine, which had a maximum sea level static thrust of 3,790 pounds. One pilot, who flew the airplane, said that at 25,000 feet, the airplane easily cruised at a true airspeed of 320 knots; the airplane's flight manual states that the airplane's maximum airspeed, without wing tanks or external stores, was 490 knots. The airplane was certified for a maximum takeoff weight of 10,600 pounds, and a maximum landing weight of 10,582 pounds. The fuselage fuel tank held 289 gallons (1,936 pounds), and two 58 gallon wing tanks held an additional 104 gal ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Abrupt maneuver, takeoff - initial climb - aircraft weight and balance - improper, pilot in command (contributing factor) - aircraft handling - abrupt, pilot in command (contributing factor) - Airframe/component/system failure/malfunction, takeoff - initial climb - window,canopy - failure (contributing factor) - Loss of control - in flight, takeoff - initial climb - diverted attention, pilot in command (contributing factor) - aircraft control - not maintained, pilot in command (cause) - lack of recent experience in type of aircraft, pilot in command (contributing factor) - stall/mush - inadvertent, pilot in command (cause) - fatigue(circadian rhythm), pilot in command (contributing factor) - In flight collision with terrain/water, descent - uncontrolled - terrain condition - open field ## Aircraft - Registration: [N602MC](https://openairdocs.org/deregistered/N602MC-2015-05-19), registration cancelled 2015-05-19, S/N 135234, built 1996 (OpenAirDocs) - Reported make and model: Aero Vodochody Aero. Works L-39CT - Registry model: [Aero Vodochody L39CT](https://openairdocs.org/model/aero-vodochody-l39ct) (registry code 05620RM) (OpenAirDocs) - Registry engine: [Ivchenko AL-25SERIES](https://openairdocs.org/engine/ivchenko-al-25series) (registry code 34702, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 135234 - Airframe hours: 118 - Engines: Ivchenko AI-25 3790 lbs thrust turbo fan - Damage: Destroyed - Fire: On-Ground - Flight: Personal, Part 91 - Registered owner: MAC Flightlease, Inc. - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, October 18, 2000, 2 hours before - Departed: FTG, Watkins, CO ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: fatal; flight instructor, airline transport, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2; last flight review August 27, 2000; seat: front; toxicology performed; flight hours: 5,100 total, 150 in this make and model, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 50° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 34 °F, dew point 25 °F - Altimeter: 30.35 inHg - Observed at: DEN, 7 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20010124001929A](https://openairdocs.org/incident/20010124001929A), Jan 24, 2001: Watkins, CO, No damage, 2 fatal. (-23) According to witnesses, the airplane departed runway 26, and turned crosswind for a southbound departure. Witnesses observed something flying from the… ## Docket (23 files) The files NTSB released with the investigation on June 20, 2002, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=51387. 9.0 MB in all. - Supplement S (item 1, .PDF, 25 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161303&FileExtension=.PDF&FileName=Supplement%20S-Master.PDF - Group Chairman's Factual Report (item 2, .PDF, 301 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161304&FileExtension=.PDF&FileName=Group%20Chairman%27s%20Factual%20Report-Master.PDF - Witness' Statements (item 3, .PDF, 742 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40387131&FileExtension=.PDF&FileName=Witness%27%20Statements-Redacted.PDF - Maps or Charts of Accident Area, Wreckage Diagrams (item 4, .PDF, 501 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161306&FileExtension=.PDF&FileName=Maps%20or%20Charts%20of%20Accident%20Area,%20Wreckage%20Diagrams-Master.PDF - Weather Reports and Records (item 5, .PDF, 34 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161307&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-Master.PDF - Reports from Local Agencies (item 6, .PDF, 220 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40387141&FileExtension=.PDF&FileName=Reports%20from%20Local%20Agencies-Redacted.PDF - Other Pertinent Forms and Reports (item 7, .PDF, 3.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40387147&FileExtension=.PDF&FileName=Other%20Pertinent%20Forms%20and%20Reports-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 8, .PDF, 50 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40387148&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 9, .PDF, 40 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40387149&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Redacted.PDF - Toxicological Report (item 10, .PDF, 56 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161315&FileExtension=.PDF&FileName=Toxicological%20Report-Master.PDF - Photo 1 - N602MC first impact ground scar (right wing tip). (item 11, .PDF, 522 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161325&FileExtension=.PDF&FileName=Photo%201%20-%20N602MC%20first%20impact%20ground%20scar%20(right%20wing%20tip).%0D%0A-Master.PDF - Photo 2 - N602MC first impact ground scar (left wing tip). (item 12, .PDF, 450 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161326&FileExtension=.PDF&FileName=Photo%202%20-%20N602MC%20first%20impact%20ground%20scar%20(left%20wing%20tip).-Master.PDF - Photo 3 - Looking from first impact to empennage. (item 13, .PDF, 382 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161327&FileExtension=.PDF&FileName=Photo%203%20-%20Looking%20from%20first%20impact%20to%20empennage.-Master.PDF - Photo 4 - N602MC's empennage. (item 14, .PDF, 292 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161329&FileExtension=.PDF&FileName=Photo%204%20-%20N602MC%27s%20empennage.-Master.PDF - Photo 5 - Right lower side of empennage. (item 15, .PDF, 215 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161330&FileExtension=.PDF&FileName=Photo%205%20-%20Right%20lower%20side%20of%20empennage.-Master.PDF - Photo 6 - Left aileron to N602MC. (item 16, .PDF, 262 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161331&FileExtension=.PDF&FileName=Photo%206%20-%20Left%20aileron%20to%20N602MC.-Master.PDF - Photo 7 - A wing tip fuel tank (auxiliary tank). (item 17, .PDF, 351 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161333&FileExtension=.PDF&FileName=Photo%207%20-%20A%20wing%20tip%20fuel%20tank%20(auxiliary%20tank).-Master.PDF - Photo 8 - The engine to N602MC. (item 18, .PDF, 226 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161334&FileExtension=.PDF&FileName=Photo%208%20-%20The%20engine%20to%20N602MC.-Master.PDF - Photo 9 - The burned fuselage of N602MC. (item 19, .PDF, 228 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161335&FileExtension=.PDF&FileName=Photo%209%20-%20The%20burned%20fuselage%20of%20N602MC.-Master.PDF - Photo 10 - The burned fuselage of N602MC. (item 20, .PDF, 223 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161336&FileExtension=.PDF&FileName=Photo%2010%20-%20The%20burned%20fuselage%20of%20N602MC.-Master.PDF - Photo 11 - The left wing of N602MC. (item 21, .PDF, 224 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161337&FileExtension=.PDF&FileName=Photo%2011%20-%20The%20left%20wing%20of%20N602MC.-Master.PDF - Photo 12 - The front canopy frame to N602MC. Both frames were found in the main wreckage. (item 22, .PDF, 335 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161338&FileExtension=.PDF&FileName=Photo%2012%20-%20The%20front%20canopy%20frame%20to%20N602MC.%20%20Both%20frames%20were%20found%20in%20the%20main%20wreckage.-Master.PDF - Photo 13 - The backseat blue depressurization knob. (item 23, .PDF, 215 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40161339&FileExtension=.PDF&FileName=Photo%2013%20-%20The%20backseat%20blue%20depressurization%20knob.-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.