# NTSB DEN99LA135: Cessna 172N, N733CK, Englewood, CO, August 4, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 4, 1999, 13:15 local (19:15 UTC) - Place: Englewood, CO - Coordinates: 39.639778, -104.990333 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.6398&lon=-104.9903&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report November 2, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46924 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN99LA135 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46924/pdf - Page: https://openairdocs.org/ntsb/DEN99LA135 ## Probable cause The unforecasted sudden wind change, and the pilot's failure to maintain aircraft control. A factor was the down sloping terrain next to the runway. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - On ground/water encounter with weather, landing - flare/touchdown - weather condition - tailwind - weather condition - dust devil/whirlwind - weather condition - sudden windshift (cause) - Loss of control - on ground/water, landing - flare/touchdown - directional control - not maintained, pilot in command (cause) - terrain condition - downhill (contributing factor) ## Analysis The student pilot was in the landing flare when the wind shifted from the left tailwind to a right tailwind. He said that the wing velocity suddenly tripled, and the airplane's right wing was thrown up at a radical angle. The airplane departed the left side of the runway and went down a steep slope, cartwheeled, and came to rest nose down. ## Factual narrative On August 4, 1999, approximately 1315 mountain daylight time, a Cessna 172N, N733CK, was substantially damaged when it departed the runway during landing roll at Centennial Airport, Englewood, Colorado. The student pilot, the sole occupant aboard the airplane, was not injured. The airplane was operated by a private individual under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the local solo instructional flight that originated approximately 10 minutes before the accident. No flight plan had been filed. The student pilot said that this was his second supervised solo, and that he was planning to stay in the traffic pattern to perform touch-and-go landings. He said that while he was on downwind leg, the tower reported a small rain shower over the center of the runway. The student pilot said that the wind had been out of the north, but when he turned final for runway 35L, he had a light left tailwind. He said that when he began to flare the airplane, the wind changed to a right tailwind and "tripled in strength." The student pilot said that "the right wing of the plane was thrown up at a radical angle." He said the airplane departed the left side of the runway and proceeded down a steep slope, cartwheeled, and came to rest nose down. ## Aircraft - Registration: [N733CK](https://openairdocs.org/deregistered/N733CK-2000-03-30), registration cancelled 2000-03-30, S/N 17268189 (OpenAirDocs) - Reported make and model: Cessna 172N - Registry model: [Cessna 172N](https://openairdocs.org/model/cessna-172n) (registry code 2072434) (OpenAirDocs) - Category: Airplane - Serial number: 17268189 - Airframe hours: 8919 - Engines: Lycoming O-360-A4A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Robert A. Estock - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, March 11, 1999, 81 hours before - Departed: APA - Airport: APA, Centennial Airport, runway 35L, 7,004 × 77 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 61; student; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 19 total, 19 in this make and model, 2 as pilot in command, 19 in the last 90 days, 16 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 320° at 3 knots - Visibility: 5 statute miles - Lowest ceiling: 5,500 ft overcast - Temperature: 66 °F, dew point 61 °F - Altimeter: 30.00 inHg - Observed at: APA ## 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 19990804047179A](https://openairdocs.org/incident/19990804047179A), Aug 4, 1999: Cessna 172N, Denver, CO, Substantial damage. (.4)The student pilot was in the landing flare when the wind shifted from the left tailwind to a right tailwind. He said that the wing velocity suddenly… 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.