# NTSB ANC99LA068: Robinson R22, N1929T, Glennallen, AK, June 2, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 1, 1999, 18:00 local (Jun 2, 1999, 02:00 UTC) - Place: Glennallen, AK - Coordinates: 62.099506, -145.529312 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=62.0995&lon=-145.5293&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report June 22, 2000 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 46531 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC99LA068 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46531/pdf - Page: https://openairdocs.org/ntsb/ANC99LA068 ## Probable cause The pilot's failure to maintain rotor RPM during takeoff. Factors associated with the accident were a downdraft, and uneven terrain. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, takeoff - weather condition - downdraft (contributing factor) - rotor rpm - not maintained, pilot in command (cause) - In flight collision with terrain/water, takeoff - terrain condition - rough/uneven (contributing factor) - Roll over, takeoff ## Analysis The certificated commercial helicopter pilot reported that during a northerly departure from atop a 4,200 feet msl mountain, the rotor rpm dropped, and the low rotor warning horn sounded. He said that in an attempt to regain rotor rpm and arrest the decent, he rolled the throttle to the high position, increased collective pitch, and lowered the nose to gain airspeed. He said that the rotor rpm continued to decay, the helicopter impacted uneven terrain, and rolled over. The pilot stated: 'I just got into a downdraft on takeoff.' He added that there were no preaccident mechanical anomalies with the helicopter. The helicopter sustained substantial damage to the rotor system, and fuselage. ## Factual narrative On June 1, 1999, about 1800 Alaska daylight time, a skid equipped Robinson R22 helicopter, N1929T, sustained substantial damage during takeoff, about 35 miles west of Glennallen, Alaska. The helicopter was being operated under Title 14, CFR Part 135, when the accident occurred. The certificated commercial pilot, and the sole passenger aboard, were not injured. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The flight originated about 0930 from a private airfield approximately 35 miles west of Glennallen. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on June 2, the pilot reported that he was conducting an on-demand charter flight for the State of Alaska, and that the passenger was a wildlife biologist employed by the State of Alaska. The pilot added that the purpose of this particular flight was to locate and retrieve electronic tracking collars that had been dropped by previously tagged moose. He said that the wildlife biologist had electronically tracked a collar located atop a 4,200 feet msl mountain. An uneventful landing and engine shutdown was made, and the biologist recovered the radio collar. The pilot stated that during a northerly departure, the rotor rpm dropped, and the low rotor warning horn sounded. He said that in an attempt to regain rotor rpm and arrest the decent, he rolled the throttle to the high position, increased collective pitch, and lowered the nose to gain airspeed. He said that the rotor rpm continued to decay, the helicopter impacted uneven terrain, and rolled over. The pilot stated: "I just got into a downdraft on takeoff." He added that there were no preaccident mechanical anomalies with the helicopter. The helicopter sustained substantial damage to the rotor system, and fuselage. ## Aircraft - Registration: [N1929T](https://openairdocs.org/deregistered/N1929T-2000-05-05), registration cancelled 2000-05-05, S/N 1929M (OpenAirDocs) - Reported make and model: Robinson R22 - Registry model: [Robinson Helicopter R22 MARINER](https://openairdocs.org/model/robinson-helicopter-r22-mariner) (registry code 7640115) (OpenAirDocs) - Category: Helicopter - Serial number: 1929M - Airframe hours: 1811 - Engines: Lycoming O-320-B2C 160 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Registered owner: Josh Johnson - Airworthiness certificate: Standard, Normal - Last inspection: Annual, May 1, 1999 - Departed: 3Z5, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 38; flight instructor, commercial; instrument ratings: helicopter; medical: class 2, unknown; seat: right; flight hours: 2,373 total, 1,806 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 300° at 5 knots - Visibility: 50 statute miles - Lowest ceiling: 10,000 ft overcast - Temperature: 48 °F, dew point 19 °F - Altimeter: 29.00 inHg ## 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 19990601006239A](https://openairdocs.org/incident/19990601006239A), Jun 1, 1999: Robsin R22MARINER, Glenallen, AK, Substantial damage. Crashed on takeoff. Other circumstance unknown. (-23) the airman picked the helicopter into a hover and pointed the ship into the light and variable wind.… 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.