# NTSB DEN01FA094: Cessna 208B, N948FE, Steamboat Spngs, CO, May 5, 2001 - Type: NTSB accident investigation - Classification: Accident · Fatal · Field investigation · Final report - Date: May 5, 2001, 08:58 local (14:58 UTC) - Place: Steamboat Spngs, CO - Coordinates: 40.45639, -106.877777 - Nearby events: https://openairdocs.org/map.md?lat=40.4564&lon=-106.8778&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed, report September 20, 2002 - Report: Approved by Office Director - NTSB case key (mKey): 52216 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN01FA094 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/52216/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=52216 - Page: https://openairdocs.org/ntsb/DEN01FA094 ## Probable cause an inadvertent stall during an instrument approach, which resulted in a loss of control. Contributing factors were the pilot's attention being diverted by an abnormal indication, conditions conducive to airframe icing, and the pilot's lack of total experience in the type of operation (icing conditions) in aircraft make/model. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, approach - iaf to faf/outer marker (ifr) - caution/warning system/light(s) - activated (contributing factor) - diverted attention, pilot in command (contributing factor) - stall - inadvertent, pilot in command (cause) - lack of total experience in type operation, pilot in command (contributing factor) - weather condition - icing conditions (contributing factor) - In flight collision with terrain/water, descent - uncontrolled - terrain condition - mountainous/hilly ## Analysis The pilot obtained a weather briefing, filed an IFR flight plan, and departed on a non-scheduled domestic cargo flight, carrying 270 pounds of freight. The flight proceeded uneventfully until it was established on the VOR/DME-C approach. Radar data indicates that after turning inbound towards the VORTAC from the DME arc, the airplane began its descent from 10,600 feet to the VOR crossing altitude of 9,200 feet. Enlargement of the radar track showed the airplane correcting slightly to the left as it proceeded inbound to the VORTAC at 9,400 feet. Shortly thereafter, aircraft track and altitude deviated 0.75 miles northwest and 9,700 feet, 0.5 miles southeast and 9,600 feet, and 0.5 miles northwest and 9,400 feet before disappearing from radar. Witnesses said the weather at the time of the accident was 600 foot overcast, 1.5 miles visibility in "misting" rain that became "almost slushy on the ground," and a temperature of 36 degrees Fahrenheit. One weather study indicated "an icing potential greater than 50% and visible moisture" in the accident area. Another report said "icing conditions were likely present in the area of the accident." The airplane was equipped and certified for flight into known icing conditions. The wreckage was found in a closely area. There was no evidence of pre-impact airframe, engine, or propeller malfunction/failure. The pilot was properly certificated, but his flight time in aircraft make/model was only 38 hours. He had previously recorded 16 icing encounters, totaling 11.2 hours in actual meteorological conditions. He recorded no ice encounters and only 1.0 hour of simulated (hooded) instrument time in the Cessna 208. Microscopic examination of annunciator light bulbs revealed the GENERATOR OFF light was illuminated. This condition indicates a generator disconnection due to a line surge, tripped circuit breaker, or inadvertent switch operation. The operator's chief pilot agreed, noting that one of the items on the Before Landing Checklist requires the IGNITION SWITCH be placed in the ON position. The START SWITCH is located next to the IGNITION SWITCH. Inadvertently moving the START SWITCH to the ON position would cause the generator to disconnect and the GENERATOR OFF annunciator light to illuminate. He said this would be distracting to the pilot. ## Factual narrative HISTORY OF FLIGHT On May 5, 2001, at 0856 mountain daylight time, a Cessna 208B, N948FE, owned by Federal Express Corporation of Memphis, Tennessee, and operated by Corporate Air, Inc., of Billings, Montana, as Airspur Flight 8810 (CPT8810), was destroyed when it collided with mountainous terrain approximately 3 miles south of Steamboat Springs, Colorado. The airline transport pilot, the sole occupant aboard, was fatally injured. Day instrument meteorological conditions prevailed, and an IFR (instrument flight rules) flight plan had been filed for the on-demand cargo flight being operated under Title 14 CFR (Code of Federal Regulations) Part 135. The flight originated in Casper, Wyoming, at 0744, and was en route to Steamboat Springs. According to Federal Aviation Administration (FAA) documents, the pilot telephoned the Casper Automated Flight Service Station (AFSS) at 0433 on the morning of May 5, and requested weather reports for stations in northwestern Colorado. He was given an "abbreviated weather briefing," that included current weather observations for Casper, Rawlins, and Rock Springs, Wyoming, and Hayden, Craig, and Aspen, Colorado; current AIRMETs (Aeronautical Meteorology) that forecast occasional moderate rime and mixed icing in clouds and precipitation from 8,000 to 20,000 feet above mean sea level (msl), mountain obscurement in all quadrants, and occasional moderate turbulence above 18,000 feet; terminal forecasts for Casper, Rock Springs, and Rawlins; and winds aloft forecast for Crazy Woman and Medicine Bow, Wyoming, at 12,000 and 18,000 feet. The briefing was terminated at 0441. According to the load manifest, the 270 pounds cargo aboard Airspur Flight 8810 consisted of "class 2.2 non-flammable" refrigerated gas and "class 1.4 explosive" (blasting caps). At 0736, the pilot contacted Casper ground control and was issued an IFR clearance to Steamboat Springs "via V26 Cherokee (CKW VORTAC, Very High Frequency Omnidirectional Radio Range-Tactical Air Navigation)," and taxi clearance to runway 3. At 0742, the pilot was cleared for takeoff, and at 0744, he contacted Casper departure control. He was issued radar vectors to join V [victor (low altitude) airway] 26 and clearance to climb to 13,000 feet. At 0758, the pilot contacted Denver ARTCC (Air Route Traffic Control Center). All aircraft on that frequency were advised of a hazardous weather AIRMET for areas west of the Mississippi, and were advised to contact Flight Watch or FSS for more information. At 0832, the pilot requested the VOR/DME-C (Very High Frequency Omnidirectional Radio Range/Distance Measuring Equipment) instrument approach to the Steamboat Springs Airport runway 32. The flight was cleared for the approach via the BQZ (Robert VORTAC) 280 degrees radial 9 DME fix. At 0839, the pilot was advised that radar services were terminated and frequency change was approved. The pilot's acknowledgement of the clearance was the last radio contact with the flight. At 0923, after the pilot failed to report being on the ground at Steamboat Springs, Sundance Aviation (BNC) flight 498 was asked to monitor for an ELT (emergency locator transmitter) signal and to attempt contact with Airspur 8810. The Sundance pilot reported receiving no ELT signals and his attempt to contact Airspur 8810 was unsuccessful. FAA issued an ALNOT (Alert Notice) at 1034. According to a statement submitted by another Corporate Air pilot, he was notified at his home approximately 0945 that the airplane was missing. He called corporate headquarters and learned the last radio contact with the flight was when it was 19 miles north of the airport and had been cleared for an instrument approach. He drove to the airport, arriving there approximately 1215, and found that the Routt County Search and Rescue (SAR) had been activated and was preparing to initiate a ground search. He and one of his flight students took off in the latter's Cessna 170 airplane approximately 1245 and begin an aerial search. Approximately 1255, they located the wreckage of N948FE on the side of Emerald Mountain, in a steep drainage, about 0.5 mile south of the Robert VORTAC. The accident occurred during the hours of daylight at a location of 40 degrees, 27.389' north latitude, and 106 degrees, 52.670' west longitude. PERSONNEL INFORMATION The 44-year-old pilot possessed an airline transport pilot certificate with an airplane multiengine land rating, and commercial privileges in airplanes, single-engine land, dated May 29, 1998. His first class airman medical certificate, dated June 5, 2000, contained no restrictions or limitations. His last proficiency check, administered by Corporate Air and dated June 5, 2000, constituted his initial checkout in the Cessna 208. The pilot's most recent logbook (number 4), containing some incomplete entries from March 27, 1995, to May 4, 2001 (the day before the accident), indicated the following (all times approximate): Total time 3,041.1 Pilot-in-command 2,887.5 Second-in-command 35.5 Airplane, single-engine 1,834.1 Airplane, multiengine 1,186.2 Airplane, turboprop 117.9 Cessna 208 37.9 Night 327.0 Actual instruments 206.4 Simulated instruments 96.0 Flight simulator 20.8 Items found amongst the pilot's personal papers were an FAA Pilot Proficiency Award Program Phase VII card, and a U.S. Department of Agriculture/Department of Interior Airplane Pilot Qualification card, endorsed for multiengine airplane with copilot, and single pilot with autopilot, and special mission endorsements for the Cessna 310, 340, 402, and 421 airplanes. The latter was issued by Lynch Flying Service, Billings, Montana, when the pilot was employed there. According to the logbook, between 1999 and 2001, the pilot logged 16 icing encounters that totaled 11.2 hours in actual instrument meteorological conditions, to wit: 04/29/99 Cessna 402C, N5774C HLN/HLN 0.2 "Flight cancelled. Icing during climb. Unable to get 80(00). Returned to Helena." 05/12/99 Cessna 402C, N6839Y HLN/BIL 0.5 "Booted three times." 06/30/99 Cessna 402C, N5774C HLN/BIL 0.7 "11-13 degrees, +RA (heavy rain), moderate IC (icing) [up to] 15,000 ft. Heavy IMC. 10/02/99 Cessna 402B, N69316 BIL/COD/BIL 1.2 "IMC, 1,000 ft. overcast, 1/2 sm, 1 in. ice accumulation." 01/11/00 Cessna 402C, N5774C COD/WRL 0.2 "Moderate ice at 9,300 ft." 01/27/00 Cessna 402C, N5774C COD/BIL 0.3 "Clear ice @ Pyror int." 3/28/00 Cessna 402C, N5774C COD/BIL 0.4 "IMC@POY, tra(ce) ic(e)." 09/19/00 Cessna 340A, N2703U M46/BIL 0.5 "Ic(e) at 8(000 ft.)" 09/21/00 Cessna 414A, N9187S BIL/WRL 0.9 "Moderate ice." 10/04/00 Cessna 402B, N69316 GTF/BIL 1.5 "2 in. (accumulation) ice." 10/11/00 Cessna 414A, N9781S BIL/GTF 0.7 "5 layers 16(00) [down to] 12(00) ov(er)c(ast), moderate ic(e)." 11/11/00 Cessna 340A, N2703U S59/MSO 0.9 "3/8-in. ice." 12/04/00 Beech 100A, N9002N BTM/BIL 0.8 "Ice 3/4-1.0 in. A/S (airspeed) 140 (knots). Boot 5-6 times." 01/05/01 Cessna 414A, N5690C BIL/FCA 1.3 "Heavy ice." 01/15/01 Beech C90, N552R G2V/BIL 0.4 "Lt. rime (ice during) climb, tops 8,000 ft." 02/09/01 Cessna 414A, N5690C BIL/SDY 0.7 "Rime to clear ice." Between March 28 to May 4, 2001, when the pilot was flying the Cessna 208 exclusively, he recorded no ice encounters and only 1.0 hour of simulated (hooded) instrument time. AIRCRAFT INFORMATION N948FE, a Cessna 208B (s/n 208B0052), was manufactured by the Cessna Aircraft Company in 1987. It was equipped with a Pratt & Whitney PT6A-114A engine (s/n 17079), rated at 675 shaft horsepower, and a Hartzell 3-blade composite, constant-speed, full feathering and reversible hydraulically actuated propeller (m/n HC-B3MN-3). According to the accident report submitted by Corporate Air, the airplane was maintained under an approved inspection program (AAIP). The airframe was last inspected on December 29, 2000. As of the date of the accident, the airframe ## Aircraft - Registration: [N948FE](https://openairdocs.org/deregistered/N948FE-2001-10-11), registration cancelled 2001-10-11, S/N 208B0052, built 1987 (OpenAirDocs) - Reported make and model: Cessna 208B - Registry model: [Cessna 208B](https://openairdocs.org/model/cessna-208b) (registry code 2073701) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52034, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 208B0052 - Airframe hours: 8690 - Engines: Lycoming PT6A-114A 675 horsepower turbo prop - Damage: Destroyed - Flight: Part 135 - Operator: Corporate Air, Inc. - Registered owner: Federal Express Corporation - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, December 29, 2000, 196 hours before - Departed: CPR, Casper, WY - Destination: SBS, Steamboat Sprin, CO - Flight plan: IFR - Airport: SBS, Steamboat Springs/Bob Adams ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 44; injuries: fatal; commercial, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; last flight review April 3, 2001; seat: left; toxicology performed; flight hours: 2,916 total, 43 in this make and model, 2,840 as pilot in command, 43 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 280° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: 800 ft broken - Temperature: 36 °F, dew point 34 °F - Altimeter: 29.95 inHg - Observed at: HDN, 21 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 20010505011749A](https://openairdocs.org/incident/20010505011749A), May 5, 2001: Cessna 208B, Steamboat Sprin, CO, No damage. (-23)No narrative ## Docket (35 files) The files NTSB released with the investigation on August 29, 2002, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=52216. 24.0 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 257 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356529&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Meteorological Group Chairman's Factual Report (item 2, .PDF, 2.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356546&FileExtension=.PDF&FileName=Meteorological%20Group%20Chairman%27s%20Factual%20Report%20-Redacted.PDF - NTSB Meteorological Group Chairman's Factual Report (item 3, .PDF, 3.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162606&FileExtension=.PDF&FileName=NTSB%20Meteorological%20Group%20Chairman%27s%20Factual%20Report-Master.PDF - NTSB Vehicle Recorder Chairman's Factual Report (item 4, .PDF, 68 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162607&FileExtension=.PDF&FileName=NTSB%20Vehicle%20Recorder%20Chairman%27s%20Factual%20Report-Master.PDF - FAA Personnel Statements (item 5, .PDF, 565 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356547&FileExtension=.PDF&FileName=FAA%20Personnel%20Statements-Redacted.PDF - Maps or Charts of Accident Area, Wreckage Diagrams (item 6, .PDF, 54 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162609&FileExtension=.PDF&FileName=Maps%20or%20Charts%20of%20Accident%20Area,%20Wreckage%20Diagrams-Master.PDF - Transcripts of Telephone and Radio Communications (item 7, .PDF, 401 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356548&FileExtension=.PDF&FileName=Transcripts%20of%20Telephone%20and%20Radio%20Communications-Redacted.PDF - NTAP Data (item 8, .PDF, 809 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162611&FileExtension=.PDF&FileName=NTAP%20Data-Master.PDF - Instrument Approach Procedure Chart (item 9, .PDF, 52 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162612&FileExtension=.PDF&FileName=Instrument%20Approach%20Procedure%20Chart-Master.PDF - Emerald Mountain (before and after the accident). (item 10, .PDF, 434 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162613&FileExtension=.PDF&FileName=Emerald%20Mountain%20(before%20and%20after%20the%20accident).-Master.PDF - Fedex Load Control Sheets and Weight Manifest (item 11, .PDF, 262 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356562&FileExtension=.PDF&FileName=Fedex%20Load%20Control%20Sheets%20and%20Weight%20Manifest-Redacted.PDF - Other Factual Reports (Meteroogical) (item 12, .PDF, 820 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356557&FileExtension=.PDF&FileName=Other%20Factual%20Reports%20(Meteroogical)-Redacted.PDF - P&W Factual Report (Fuel Control Unit and Pump) (item 13, .PDF, 765 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162616&FileExtension=.PDF&FileName=P%26W%20Factual%20Report%20(Fuel%20Control%20Unit%20and%20Pump)-Master.PDF - Cessna Factual Report (Ejector Flow Control Valve) (item 14, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162618&FileExtension=.PDF&FileName=Cessna%20Factual%20Report%20(Ejector%20Flow%20Control%20Valve)-Master.PDF - Cessna Factual Report (Deice System Vacuum Valves) (item 15, .PDF, 348 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162620&FileExtension=.PDF&FileName=Cessna%20Factual%20Report%20(Deice%20System%20Vacuum%20Valves)-Master.PDF - Cessna Factual Report (Annuniciator Panel Light Bulb Filaments) (item 16, .PDF, 684 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162622&FileExtension=.PDF&FileName=Cessna%20Factual%20Report%20(Annuniciator%20Panel%20Light%20Bulb%20Filaments)-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 17, .PDF, 74 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356565&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 18, .PDF, 36 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356564&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Redacted.PDF - Toxicological Report (item 19, .PDF, 54 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356554&FileExtension=.PDF&FileName=Toxicological%20Report-Redacted.PDF - Photo 1 - View to the north. Wreckage is in foreground, Robert VORTAC is just over the ridge. (item 20, .PDF, 639 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162543&FileExtension=.PDF&FileName=Photo%201%20-%20View%20to%20the%20north.%20%20Wreckage%20is%20in%20foreground,%20Robert%20VORTAC%20is%20just%20over%20the%20ridge.-Master.PDF - Photo 2 - Aerial view of accident site. (item 21, .PDF, 719 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162545&FileExtension=.PDF&FileName=Photo%202%20-%20Aerial%20view%20of%20accident%20site.-Master.PDF - Photo 3 - Looking down from mountain slope at accident site. (item 22, .PDF, 754 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162546&FileExtension=.PDF&FileName=Photo%203%20-%20Looking%20down%20from%20mountain%20slope%20at%20accident%20site.-Master.PDF - Photo 4 - Severed trees. (item 23, .PDF, 734 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162547&FileExtension=.PDF&FileName=Photo%204%20-%20Severed%20trees.-Master.PDF - Photo 5 - Severed tree and cockpit area. (item 24, .PDF, 702 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162548&FileExtension=.PDF&FileName=Photo%205%20-%20Severed%20tree%20and%20cockpit%20area.-Master.PDF - Photo 6 - Main body of wreckage. (item 25, .PDF, 713 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162549&FileExtension=.PDF&FileName=Photo%206%20-%20Main%20body%20of%20wreckage.-Master.PDF - Photo 7 - Main body of wreckage. (item 26, .PDF, 749 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162550&FileExtension=.PDF&FileName=Photo%207%20-%20Main%20body%20of%20wreckage.-Master.PDF - Photo 8 - Main body of wreckage. (item 27, .PDF, 711 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162551&FileExtension=.PDF&FileName=Photo%208%20-%20Main%20body%20of%20wreckage.-Master.PDF - Photo 9 - Right wing. (item 28, .PDF, 678 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162552&FileExtension=.PDF&FileName=Photo%209%20-%20Right%20wing.-Master.PDF - Photo 10 - Tail section. (item 29, .PDF, 746 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162553&FileExtension=.PDF&FileName=Photo%2010%20-%20Tail%20section.-Master.PDF - Photo 11 - Cargo pod. (item 30, .PDF, 751 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162554&FileExtension=.PDF&FileName=Photo%2011%20-%20Cargo%20pod.-Master.PDF - Photo 12 - Cargo consisted of class 1.4 explosive, or blasting caps. (item 31, .PDF, 704 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162555&FileExtension=.PDF&FileName=Photo%2012%20-%20Cargo%20consisted%20of%20class%201.4%20explosive,%20or%20blasting%20caps.-Master.PDF - Photo 13 - The cockpit. (item 32, .PDF, 693 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162556&FileExtension=.PDF&FileName=Photo%2013%20-%20The%20cockpit.-Master.PDF - Photo 14 - Propeller assembly after removal from crater. (item 33, .PDF, 724 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162557&FileExtension=.PDF&FileName=Photo%2014%20-%20Propeller%20assembly%20after%20removal%20from%20crater.-Master.PDF - Photo 15 - Flap jackscrew extension indicated 10 degrees down. (item 34, .PDF, 678 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162559&FileExtension=.PDF&FileName=Photo%2015%20-%20Flap%20jackscrew%20extension%20indicated%2010%20degrees%20down.-Master.PDF - Photo 16 - Elevator jackscrew. (item 35, .PDF, 677 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40162560&FileExtension=.PDF&FileName=Photo%2016%20-%20Elevator%20jackscrew.-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.