# NTSB DEN99LA028: Burkhart Grob G103 Twin Astir, N173SS, Canon City, CO, December 27, 1998 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: December 27, 1998, 11:15 local (18:15 UTC) - Place: Canon City, CO - Coordinates: 38.440254, -105.23027 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.4403&lon=-105.2303&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious, 1 minor - Status: Completed, report February 16, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 45547 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN99LA028 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/45547/pdf - Page: https://openairdocs.org/ntsb/DEN99LA028 ## Probable cause The glider pilot's failure to follow proper preflight procedures, and his failure to control the aircraft when the latch opened during flight. A factor was his failure to properly latch the canopy, and to utilize all available runway during the forced landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Miscellaneous/other, takeoff - initial climb - window,canopy - open - aircraft preflight - not followed, pilot in command (cause) - window,canopy - unlatched (contributing factor) - aircraft control - not maintained, pilot in command (cause) - Forced landing, descent - emergency - all available runway - not used, pilot in command (contributing factor) - In flight collision with terrain/water, emergency descent/landing - terrain condition - grass ## Analysis During initial climb from takeoff, the rear canopy of the glider opened. When the pilot reached to close the canopy, the glider ballooned above the tow plane. The pilot turned the glider to the left and lowered the nose to maintain airspeed. The glider then impacted the ground before he leveled out. According to the passenger and several witnesses, prior to takeoff, the glider pilot signaled the tow pilot that he was ready for takeoff. However, the departure was halted so that the glider pilot could be given a handheld radio in order for communications to be established between the glider and the tow plane. The glider pilot opened the canopy in order to receive the radio, then re-closed it. The first ground scars were observed approximately 1,100 feet prior to the end of the paved section of runway 29, and an additional 800 feet of dirt extends beyond the runway prior to the existence of any obstructions. At the request of an FAA inspector, a postaccident examination of the rear canopy latch was performed. According to the mechanic who performed the inspection, 'the rear canopy latch was found to be operational.' ## Factual narrative On December 27, 1998, at 1115 mountain standard time, a Burkhart Grob Flugzeugbau G103 Twin Astir glider, N173SS, was substantially damaged when it impacted the ground following a forced landing after the canopy opened during initial climb from takeoff at Freemont County Airport, Canon City, Colorado. The commercial pilot received minor injuries and one passenger received serious injuries. Visual meteorological conditions prevailed for the local area personal flight being conducted under Title 14 CFR Part 91, and no flight plan was filed. The flight originated approximately five minutes before the accident. According to the glider pilot, the passenger "was strapped in and [the] canopy [was] latched in the front seat." He then "latched the canopy in the rear seat and performed a normal pre-takeoff checklist." The tow plane was attached and takeoff was normal. After a positive rate of climb was established, the rear canopy "popped open." When the pilot attempted to close the canopy, the glider ballooned above the tow plane. He then instructed the passenger to pull the tow rope release. He turned to the left in an attempt to land on flatter terrain, and lowered the nose to maintain airspeed. According to the pilot, the glider impacted the ground before he could level out. According to the passenger and several witnesses, the glider pilot signaled the tow pilot that he was ready for takeoff. However, the departure was halted so that the glider pilot could be given a handheld radio in order for communications to be established between the glider and the tow plane. The glider pilot opened the canopy in order to receive the radio, then re-closed it. The glider pilot then signaled a second time that he was ready for takeoff. After departure, the passenger stated that the aircraft was 5 to 10 feet above the runway when the canopy latch opened. According to a witness, at approximately 100 feet above the ground (agl), "the glider pitched up steeply, lifting the tail of the tow plane. The glider and tow plane both released the rope which landed near taxiway A3 [located mid-runway]... The glider then traveled approximately 1,500 to 2,000 feet down the runway before turning left and impacting the ground left wing first." According to a witness, the first ground scars where the glider impacted the ground were observed approximately 1,100 feet prior to the end of the paved section of runway 29. In addition, there is another 800 feet of dirt beyond the paved runway prior to the existence of any obstructions. At the request of the Investigator-In-Charge, an FAA inspector supervised an examination of the rear canopy latch. According to the mechanic who performed the inspection, "the rear canopy latch was found to be operational." ## Aircraft - Registration: [N173SS](https://openairdocs.org/deregistered/N173SS-2013-04-18), registration cancelled 2013-04-18, S/N 3286, built 1980 (OpenAirDocs) - Reported make and model: Burkhart Grob G103 TWIN ASTIR (G103 TWIN) - Registry model: [Burkhart Grob Flugzeugbau G103 TWIN ASTIR](https://openairdocs.org/model/burkhart-grob-flugzeugbau-g103-twin-astir) (registry code 1660202) (OpenAirDocs) - Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs) - Category: Glider - Serial number: 3286 - Engines: unknown - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Peak Soaring - Registered owner: John M. Duprey - Airworthiness certificate: Standard, Normal - Departed: 1V6 - Airport: IV6, Freemont County Airport, runway 29, 5,399 × 75 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 52; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: unknown; seat: rear; flight hours: 1,700 total, 30 in this make and model, 1,525 as pilot in command, 3 in the last 90 days, 1 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 260° at 15 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 45 °F ## 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 19981227033859A](https://openairdocs.org/incident/19981227033859A), Dec 27, 1998: Grob G103TWNASTIR, Canon City, CO, Destroyed. Grob G-103 glider experienced canopy problems on take-off. (.19)on December 27, 1998, at 1115 mountain standard time, a burkhart Grob flugzeugbau G103 twin… ## Other investigations on N173SS (1) 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. - [NTSB LAX92LA275](https://openairdocs.org/ntsb/LAX92LA275), Jul 3, 1992: Burkhart Grob G103 (N173SS), Olancha, CA, substantial damage. Probable cause: 1) THE TOW PILOT'S INTENTIONAL PREMATURE RELEASE OF THE GLIDER, WHICH HAD BECOME AIRBORNE, WHEN THE TOW PLANE FAILED TO ACHIEVE SUFFICIENT AIRSPEED DURING ITS TAKEOFF GROUND ROLL, AND, 2) THE GLIDER… 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.