Cessna 172 accident near Bally, Pennsylvania, September 21, 2015
On September 21, 2015 at about 10:30 pm local time, a 1999 Cessna 172, registered N347SP, was substantially damaged in an accident during maneuvering (low-alt flying) near Bally, Pennsylvania (Butter Valley Golf Port airport). It was a personal flight under general aviation rules (Part 91). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot's failure to maintain altitude during low-level aerobatic maneuvers. Contributing to the accident were the pilot's improper decision to attempt the low-level aerobatic maneuvers and his impairment due to psychiatric conditions and the medications he was using to treat them.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 21, 2015 · about 10:30 pm local time
- Place
- Bally, Pennsylvania · Butter Valley Golf Port · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 172 S, built 1999 · all 172s on the register
- Registration
- N347SP · no longer on the register · serial 172S8271
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The commercial pilot was conducting a personal cross-country flight. Several witnesses reported observing different sequences of events. One witness reported seeing the airplane fly in a 90° right bank turn for about 10 seconds as it maneuvered underneath power lines and between two utility towers. After passing under the power lines, the airplane leveled and then impacted the ground. Another witness reported that the airplane was at a lower-than-normal altitude and seemed to be flying "erratically" and "aggressively," and that, at one point, it was "flying on its side." Another witness reported seeing the airplane flying with one wing pointing toward the ground. The witness statements are consistent with low-altitude aerobatic maneuvers. Although some bystanders reported that the engine sputtered and lost power and the pilot reported that a loss of engine power occurred, postaccident examination of the airframe and engine, which included a successful engine test run, revealed no preimpact mechanical malfunctions or failures that would have precluded normal operation. Toxicological testing of the pilot's specimens revealed that he had high levels of a sedating benzodiazepine, alprazolam, within the toxic range. Additionally, he had a low level of a second sedating benzodiazepine, lorazepam. Both these medications are used to treat significant anxiety disorders, which are associated with performance deficits, particularly in high-workload spatial tasks. It is likely that the pilot's underlying psychiatric disorders and the medications he was using to treat them impaired his judgement, executive functioning, and psychomotor skills and contributed to the accident.
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
- Miscellaneous/other during maneuvering (aerobatics)
- Loss of control in flight during maneuvering (low-alt flying) defining event
- Collision with terrain or object (not controlled flight into terrain) during maneuvering (low-alt flying)
The NTSB's findings
- cause Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Altitude › Not attained/maintained
- factor Personnel issues › Psychological › Mental/emotional state › (general) › Pilot
- factor Personnel issues › Physical › Impairment/incapacitation › Prescription medication › Pilot
- factor Personnel issues › Action/decision › Info processing/decision › Decision making/judgment › Pilot
- Environmental issues › Physical environment › Object/animal/substance › Fence/fence post › Contributed to outcome
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 1,550 hours in all; 1,300 in this make and model; 200 in the last 90 days; 75 in the last 30 days; 1,250 as pilot in command; 900 on instruments
- Last flight review: January 29, 2015
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: left
- Injury: minor injuries
The aircraft
- Airframe total time: 5,542 hours
- Last inspection: 100-hour inspection, September 18, 2015; 7 hours since
- Maximum gross weight: 2,550 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming IO-360 (piston); 725 hours total
- Operator: Certified Aviation LLC
The flight
- Departed from: 7N8 Bally PA at 10:30 pm
- Destination: MMU Morristown NJ
- Flight plan: none
- Runway 34, 2,420 ft by 85 ft
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: broken clouds at 11,000 ft
- Temperature: 64°F (18°C), dew point 48°F (9°C)
- Altimeter: 30.20 inHg
- Observation at 10:54 pm from PTW, 11 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
16 documents, released by the NTSB on February 13, 2017. 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 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 10 pages | View Download |
| 2 | Excerpt from Ems/emt Report | PDF, 1 page | View Download |
| 3 | Witness Statements | PDF, 4 pages | View Download |
| 4 | Interview Summaries | PDF, 3 pages | View Download |
| 5 | Additional Interview Summary | PDF, 1 page | View Download |
| 6 | Excerpts from Maintenance Records | PDF, 1 page | View Download |
| 7 | Memoranda for Record | PDF, 2 pages | View Download |
| 8 | Photo Array | PDF, 5 pages | View Download |
| 9 | Map of Accident Site | PDF, 1 page | View Download |
| 10 | Toxicological Report | PDF, 2 pages | View Download |
| 11 | Medical Factual Report | PDF, 3 pages | View Download |
| 12 | Release of Aircraft Wreckage, NTSB Form 6120.15 | PDF, 1 page | View Download |
| 13 | Modified Factual Narrative Report | PDF, 3 pages | View Download |
| 14 | ERA15LA366 Petition | PDF, 19 pages | View Download |
| 15 | ERA15LA366 Petition Reponse | PDF, 23 pages | View Download |
| 16 | ERA15LA366 Changes to Final Information | PDF, 3 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.