# NTSB FTW99LA238: Burkhart Grob 103C, N103MS, San Antonio, TX, August 28, 1999 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: August 28, 1999, 13:00 local (18:00 UTC) - Place: San Antonio, TX - Coordinates: 29.800825, -98.729133 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=29.8008&lon=-98.7291&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report December 4, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 47199 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW99LA238 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/47199/pdf - Page: https://openairdocs.org/ntsb/FTW99LA238 ## Probable cause The pilot's failure to attain proper runway alignment of the glider resulting in failure to maintain obstacle clearance. A factor was the high density altitude. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with object, approach - vfr pattern - final approach - weather condition - high density altitude (contributing factor) - proper alignment - not attained, pilot in command (cause) - clearance - not maintained, pilot in command (cause) - object - tree(s) - In flight collision with terrain/water, descent - uncontrolled ## Analysis The wing of the glider struck a tree when the solo student pilot was correcting the flight path to align the glider with the runway centerline during the final approach. The density altitude was calculated at 4,215 feet. The student pilot had 15.2 hours of total flight time in gliders. He was endorsed for solo flight and had 2.4 hours of solo flight time in the glider. The operator reported that the accident could have been prevented by 'maintain[ing] adequate clearance over obstacles.' ## Factual narrative On August 28, 1999, at 1300 central daylight time, a Grob 103C glider, N103MS, struck a tree during the final approach to runway 17 at the Boerne Stage Field Airport near San Antonio, Texas. The glider was owned and operated by Alamo Aerodyne Corporation, San Antonio, Texas, under 14 Code of Federal Regulations (CFR) Part 91. The solo student pilot received serious injuries and the glider sustained substantial damage. Visual meteorological conditions prevailed for the local solo instructional flight and a flight plan was not filed. The flight departed the Boerne Stage Field Airport at 1200. Witnesses and local authorities reported that the student pilot, while turning final approach, over shot the runway. The pilot was correcting the flight path toward the runway when the right wing struck a tree approximately 5 1/2 inches in diameter. The glider pivoted around the tree and stuck the ground in a nose down attitude. The glider came to rest approximately 300 feet short of the runway. The FAA inspector and the glider owner examined the glider and found that the inboard 18 to 24 inches of the right wing was damaged and the forward cabin was crushed. Approximately 4 1/2 feet of the outboard right wing was found separated from the glider. The student pilot had 15.2 hours of total flight time in gliders. The student was endorsed for solo flight and had 2.4 hours of solo flight time in the glider. On the Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1/2, the operator reported that the accident could have been prevented by "maintain[ing] adequate clearance over obstacles." The National Weather Service observation for San Antonio, Texas, (located 13 nautical miles west of the accident site), at 1255 was 96 degrees Fahrenheit with an altimeter setting of 29.90 inches. The NTSB investigator-in-charge calculated the density altitude at 4,215 feet. ## Aircraft - Registration: [N103MS](https://openairdocs.org/deregistered/N103MS-2011-01-28), registration cancelled 2011-01-28, S/N 34156, built 1990 (OpenAirDocs) - Reported make and model: Burkhart Grob 103C - Registry model: [Burkhart Grob G103C TWIN III ACRO](https://openairdocs.org/model/burkhart-grob-g103c-twin-iii-acro) (registry code 1660207) (OpenAirDocs) - Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs) - Category: Glider - Serial number: 34-756 - Airframe hours: 1049 - Engines: unknown - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Bob Bruce - Airworthiness certificate: Standard, Aerobatic - Last inspection: Annual, June 4, 1999, 85 hours before - Departed: 5C1 - Airport: 5C1, Boerne Stage Field, runway 17, 3,400 × 40 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; student; medical: unknown, unknown; seat: front; flight hours: 15 total, 15 in this make and model, 2 as pilot in command, 15 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: 160° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 97 °F, dew point 63 °F - Altimeter: 29.00 inHg - Observed at: SAT, 13 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 19990828036779A](https://openairdocs.org/incident/19990828036779A), Aug 28, 1999: Grob G103CTWINIII, San Antonio, TX, Substantial damage. (.4) The wing of the glider struck a tree when the solo student pilot was correcting the flight path to align the glider with the runway centerline during the… ## Other investigations on N103MS (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 CEN09LA353](https://openairdocs.org/ntsb/CEN09LA353), Jun 14, 2009: Burkhart Grob G103C Twin III Acro (N103MS), Gregory, MI, substantial damage, 1 fatal. Probable cause: The pilot's failure to maintain sufficient airspeed during the turn to return for landing, which resulted an inadvertent stall/spin. Contributing to the accident was the failure of the ground winch… 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.