# NTSB ATL99LA033: Robinson R-22B, N2321X, Lantana, FL, December 10, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 10, 1998, 14:00 local (19:00 UTC) - Place: Lantana, FL - Coordinates: 26.579698, -80.069839 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=26.5797&lon=-80.0698&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report March 31, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 45453 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL99LA033 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/45453/pdf - Page: https://openairdocs.org/ntsb/ATL99LA033 ## Probable cause The pilot's improper use of the flight controls during an attempted autorotation. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, approach - autorotation - attempted, pilot in command - flight controls - improper use of, pilot in command (cause) - In flight collision with terrain/water, emergency descent/landing - terrain condition - grass - object - other ## Analysis The flight instructor was demonstrating a 180-degree autorotation, with power recovery. As the helicopter descended through 200 feet, the low rotor RPM horn sounded. The tachometer was about 92 percent. The flight instructor then rolled on the throttle and went down on the collective simultaneously. The instructor stated that his descent rate was too great to arrest the sink. The instructor attempted a shallow flare, and cushioned with collective. The helicopter contacted the ground in a level attitude.. The aircraft slid in grass, the right skid dug into the ground and the helicopter rolled over. No mechanical problems with the airplane were discovered during the wreckage examination. ## Factual narrative On December 10, 1998, at 1400 eastern standard time, a Robinson R-22B, helicopter, N2321X, collided with the ground, during a practice autorotation, at the Lantana Airport, in Lantana, Florida. The instructional flight was operated by Aircoastal Helicopter under the provisions of Title 14 CFR Part 91 with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The helicopter sustained substantial damage. The flight instructor and the dual student were not injured. The flight departed Lantana, Florida, at 1350. The flight instructor reported that he and the dual student were conducting autorotation training. The dual student had completed several power recovery autorotations, and the session had progressed to the point where the dual student was ready for a 180-degree autorotation. The flight instructor was demonstrating a 180-degree autorotation, with power recovery, when the accident occurred. The flight instructor stated that "all airplane instruments were in the green, all warning lights were out, and the carburetor was heat on." Also the instructor noted that the carburetor air temperature gauge(CAT) was in the normal range. As the helicopter descended through two-hundred feet, the low rotor RPM horn sounded. The tachometer was at about ninety-two percent. The flight instructor then, "rolled on throttle and went down on the collective simultaneously." The flight instructor attempted a shallow flare, and attempted to cushioned the helicopter with the collective. At this point the flight instructor realized the rate of descent was too great to arrest. The helicopter contacted the ground in a level attitude with the skids aligned with the runway heading. The aircraft slid in the grass, the right skid dug into the ground, and the helicopter rolled over on the left side. The flight instructor turned off the battery as they exited the aircraft. Wreckage examination revealed that the carburetor heat was found in the on position, and the throttle linkage appeared to function normally. Examination of the helicopter and the engine assembly failed to disclose a mechanical malfunction or a component failure. A review of weather data disclosed that conditions were favorable for the formation of carburetor ice. ## Aircraft - Registration: [N2321X](https://openairdocs.org/deregistered/N2321X-2000-12-08), registration cancelled 2000-12-08, S/N 1976 (OpenAirDocs) - Reported make and model: Robinson R-22B - Registry model: [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta) (registry code 7640110) (OpenAirDocs) - Category: Helicopter - Serial number: 1976 - Airframe hours: 2398 - Engines: Lycoming O-320-B2C 124 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Aircoastal Helicopter Inc., - Registered owner: R.W. Helicopters - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, October 8, 1998, 85 hours before - Departed: LNA - Airport: LNA, Palm Beach County Park, runway 9, 3,489 × 75 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 31; commercial, flight instructor; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 320 total, 260 in this make and model, 220 as pilot in command, 45 in the last 90 days, 40 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 100° at 11 knots, gusting 5 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 63 °F - Altimeter: 30.00 inHg - Observed at: PBI, 10 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 19981210044229A](https://openairdocs.org/incident/19981210044229A), Dec 10, 1998: Robsin R22BETA, West Palm Beach, FL, Substantial damage. (.19)On December 10, 1998, at 1400 eastern standard time, a Robinson R-22, helicopter, N2321X, collided with the ground, according to the flight instructor,… ## Other investigations on N2321X (2) 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 MIA95LA128](https://openairdocs.org/ntsb/MIA95LA128), May 7, 1995: Robinson R22 Beta (N2321X), Miami, FL, substantial damage. Probable cause: INADEQUATE SUPERVISION BY THE CFI FOR ALLOWING THE STUDENT TO INITIATE INITIAL FLARE AND POWER RECOVERY AT 100 FEET INSTEAD OF 40 FEET AND 40 FEET INSTEAD OF 8-10 FEET RESPECTIVELY. ADDITIONALLY,… - [NTSB MIA93LA004](https://openairdocs.org/ntsb/MIA93LA004), Oct 5, 1992: Robinson R22 Beta (N2321X), Naples, FL, substantial damage. Probable cause: INCORRECT AIRSPEED, INSUFFICIENT AIRSPEED, AND FAILURE OF THE PILOT IN COMMAND TO PERFORM THE CORRECT EMERGENCY PROCEDURE FOLLOWING THE IN FLIGHT LOSS OF CONTROL. CONTRIBUTING TO THE ACCIDENT WAS… 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.