Robinson Helicopter R22 accident near Palmer, Alaska, December 18, 2016
On December 18, 2016 at about 8:00 pm local time, a 1985 Robinson Helicopter R22, registered N121MR, was substantially damaged in an accident during landing near Palmer, Alaska. It was an instructional flight under general aviation rules (Part 91). 2 people had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot's failure to maintain main rotor revolutions per minute (RPM) during a pinnacle landing, which resulted in a main rotor stall condition, a loss of control, and a subsequent impact with terrain. A contributing factor was the flight instructor's failure to monitor the main rotor RPM during the pinnacle landing.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- December 18, 2016 · about 8:00 pm local time
- Place
- Palmer, Alaska · map
- Type
- Accident
- Injuries
- 2 people had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Robinson Helicopter R22, built 1985 · all R22s on the register
- Registration
- N121MR · no longer on the register · serial 0496
- Damage
- Substantial damage
- Flight
- Instructional flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The flight instructor stated that he was providing flight instruction to the private pilot, practicing pinnacle landings to an area of remote, snow-covered mountainous terrain. The flight instructor said that just before the accident, the private pilot accomplished two successful pinnacle landings. After a third pinnacle landing site was selected, a gravel-covered site on a mountain ridgeline, the private pilot circled the site several times for reconnaissance. He reported that as the helicopter neared the site, about 10 to 20 feet above the surface, he realized that it had a steep uphill grade making the site unsuitable for landing. He explained that, as he was getting ready to tell the private pilot to initiate a go-around, the low rotor revolutions per minute (RPM) warning light and horn activated. The private pilot reported that when the low rotor RPM warning light and horn activated, he observed the gauge indicated about 90 percent RPM. The flight instructor then took control of the helicopter, attempting to maneuver it to the right and towards the predetermined escape route, but it descended and the skids subsequently struck the uneven terrain. He said that after the initial collision, he increased collective pitch and applied right cyclic, but it began to spin to the right, while descending. The helicopter continued to spin, while descending, and it subsequently struck an area of steep, snow-covered terrain. The helicopter then rolled downhill multiple times before coming to rest in an area of steep, snow-covered terrain.
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
- Simulated/training event during landing
- Miscellaneous/other during landing defining event
- Attempted remediation/recovery during landing
- Loss of control in flight during landing
- Collision with terrain or object (not controlled flight into terrain) during landing
The NTSB's findings
- cause Personnel issues › Action/decision › Action › Delayed action › Instructor/check pilot
- cause Personnel issues › Task performance › Use of equip/info › Aircraft control › Student/instructed pilot
- cause Personnel issues › Action/decision › Action › Incorrect action performance › Student/instructed pilot
- cause Personnel issues › Psychological › Attention/monitoring › Task monitoring/vigilance › Instructor/check pilot
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Prop/rotor parameters › Not attained/maintained
Flight instructor
- Certificate: flight instructor, commercial pilot
- Ratings: instructor: helicopter; instructor: instrument helicopter; instrument: helicopter; rotorcraft: helicopter
- Flight time: 257.8 hours in all; 161.1 in this make and model; 32.5 in the last 90 days; 7.8 in the last 30 days; 188.3 as pilot in command; 38 on instruments
- Last flight review: June 24, 2016
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: left
- Injury: minor injuries
Pilot
- Certificate: private
- Ratings: rotorcraft: helicopter
- Flight time: 82.4 hours in all; 82.4 in this make and model; 20 as pilot in command
- Medical certificate: Class 3 (without waivers/limitations)
- Seat: rgt
- Injury: minor injuries
The aircraft
- Airframe total time: 3,417.4 hours
- Last inspection: 100-hour inspection, September 16, 2016
- Maximum gross weight: 1,370 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O-320-B2C (piston); 3,445 hours total
- Operator: Castor Aviation LTD
The flight
- Departed from: 4AK6 Palmer AK
- Destination: 4AK6 Palmer AK
- Flight plan: none
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 020° at 18 knots, gusting 24
- Visibility: 10 statute miles
- Sky: broken clouds at 14,000 ft; scat at 8,000 ft
- Temperature: 34°F (1°C), dew point 14°F (-10°C)
- Altimeter: 28.86 inHg
- Observation at 7:53 pm from PAAQ, 10 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 2 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
3 documents, released by the NTSB on August 29, 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, 11 pages | View Download |
| 2 | Flight Instructor Statement | PDF, 1 page | View Download |
| 3 | Photos (Courtesy of Flight Instructor) | 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.
Other NTSB records under N121MR the same tail number, which may have belonged to a different aircraft at the time
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.