Glaser Dirks DG500 accident near Marana, Arizona, October 6, 2019
On October 6, 2019 at about 8:00 pm local time, a 1994 Glaser Dirks DG500 (glider), registered N600TT, was substantially damaged in an accident during maneuvering (aerobatics) near Marana, Arizona (El Tiro airport). It was a personal flight under general aviation rules (Part 91). 1 person had minor injuries; 1 other was unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilots’ exceedance of the glider’s never-exceed speed (VNE) during recovery from an intentional aerobatic maneuver, which resulted in a failure of the right-wing air brake control drive, asymmetrical air brake deployment, and a subsequent hard landing.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- October 6, 2019 · about 8:00 pm local time
- Place
- Marana, Arizona · El Tiro · map
- Type
- Accident
- Injuries
- 1 person had minor injuries; 1 other was unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Glaser Dirks DG500 TRAINER, built 1994
- Registration
- N600TT · no longer on the register · serial 5E 119 T50
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilots were performing aerobatic maneuvers in the glider. While recovering from a maneuver, the glider’s airspeed increased past the never-exceed speed (Vne) and the elevator began to flutter. The right air brake (spoiler) deployed fully, though the spoiler control was in the locked position. After assessing the controllability of the glider, the pilots chose to land at the gliderport rather than perform an emergency egress. The glider landed hard and impacted brush, resulting in the separation of the empennage at the tailboom. Postaccident examination revealed a separation of the right-wing air brake control drive system at the rod end, which resulted in the asymmetrical spoiler extension. The manufacturer stated that it should have been possible to deploy the left-wing air brake normally to compensate for the asymmetric behavior and have some (reduced) control over the approach glidepath. The manufacturer also stated there is no emergency procedure described in the flight manual for air brake malfunctions. It is likely that the air brake control separation was the result of the pilots’ exceedance of Vne during recovery from the aerobatic maneuver.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Flight control sys malf/fail during maneuvering (aerobatics) defining event
The NTSB's findings
- Aircraft › Aircraft structures › Wing structure › Attach fittings (on wing) › Capability exceeded
- Personnel issues › Action/decision › Action › Incorrect action performance › Pilot
- Personnel issues › Action/decision › Action › Incorrect action performance › Instructor/check pilot
- Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Airspeed › Capability exceeded
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; single-engine sea; rotorcraft: glider
- Flight time: 2,249 hours in all; 8 in this make and model; 11 in the last 90 days; 1 in the last 30 days; 2,200 as pilot in command
- Last flight review: September 17, 2019
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: rear
- Injury: minor injuries
Pilot
- Certificate: private
- Ratings: single-engine land; rotorcraft: glider
- Flight time: 269 hours in all; 13 in this make and model; 44 in the last 90 days; 22 in the last 30 days; 130 as pilot in command
- Last flight review: April 3, 2019
- Medical certificate: Class 1 (with waivers/limitations)
- Seat: frt
- Injury: no injuries
The aircraft
- Airframe total time: 1,944 hours
- Last inspection: condition inspection, May 11, 2019
- Maximum gross weight: 1,356 lb
- Seats: 2
- Landing gear: retractable
- Operator: Tucson Soaring Club Inc.
The flight
- Departed from: AZ67 Tucson AZ at 7:30 pm
- Destination: AZ67 Tucson AZ
- Flight plan: none
- Runway 35L, 5,000 ft by 130 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 270° at 5 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 90°F (32°C), dew point 43°F (6°C)
- Altimeter: 30.07 inHg
- Observation at 7:45 pm from KRYN, 20 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
6 documents, released by the NTSB on March 8, 2022. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Commercial Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 2 | Pui Pilot/operator Aircraft Accident Report NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 3 | Record of Conversations | PDF, 4 pages | View Download |
| 4 | Air Brake Technical Letter | PDF, 5 pages | View Download |
| 5 | Flight Manual Excerpt | PDF, 4 pages | View Download |
| 6 | Photo Array and Diagram (All Provided by Pilot) | PDF, 4 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.