# NTSB SEA98LA185: Duncan DX4, N4DX, Priest River, ID, September 22, 1998 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: September 21, 1998, 17:00 local (Sep 22, 1998, 00:00 UTC) - Place: Priest River, ID - Coordinates: 48.129379, -116.990974 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=48.1294&lon=-116.9910&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report January 11, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 44001 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA98LA185 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/44001/pdf - Page: https://openairdocs.org/ntsb/SEA98LA185 ## Probable cause The pilot's failure to maintain adequate airspeed which resulted in a stall/mush. Factors include allowing his attention to be diverted by what he perceived to be a lateral control problem. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with terrain/water, approach - vfr pattern - base turn - airspeed(vs) - inadequate, pilot in command (cause) - stall/mush - inadvertent, pilot in command (cause) - diverted attention, pilot in command (contributing factor) - terrain condition - ground ## Analysis After turning downwind in the experimental aircraft, the pilot sensed that the lateral flight controls were not responding to his inputs as he thought they would. He therefore elected to continue around the pattern and land. Because he felt that a reduction in power positively effected the perceived control problem, he reduced power on downwind and then attempted to turn base. Witnesses said that the aircraft was going very slow prior to turning base, and that as it entered a left bank, it fell out of the sky. Just prior to impacting the ground, the aircraft rolled wings-level. No problem with the lateral flight control system was able to be identified, and no reason for the perceived lateral control anomaly was determined. ## Factual narrative On September 21, 1998, approximately 1700 Pacific daylight time, an experimental Duncan DX4, N4DX, impacted the terrain just after the pilot initiated the turn from downwind to base at Priest River Municipal Airport, Priest River, Idaho. The private pilot, who was the sole occupant, received serious injuries, and the aircraft, which was owned and operated by the pilot, sustained substantial damage. The 14 CFR Part 91 personal pleasure flight, which was being conducted in the VFR traffic pattern, had been initiated less than five minutes prior to the accident. No flight plan had been filed, and there was no report of an ELT activation. According to the FAA Inspector who interviewed the pilot, while on downwind he thought that the aircraft was not responding to his lateral control inputs in the manner he expected it to. He therefore decided to continue around the pattern and make a full-stop landing. Because it seemed to the pilot that a reduction in engine power positively effected the perceived control problem, he reduced power on downwind and then attempted to turn base. Witnesses said that just prior to the base turn, the aircraft appeared to be going very slow. They also reported that as the aircraft entered a left bank, it appeared to fall out of the sky. Just prior to impacting the ground, the aircraft rolled back to a near wings-level position. According to the pilot/owner, no problem with the lateral flight control system was able to be identified, and no reason for the perceived lateral control anomaly was determined. ## Aircraft - Registration: [N4DX](https://openairdocs.org/deregistered/N4DX-2000-10-27), registration cancelled 2000-10-27, S/N 1 (OpenAirDocs) - Reported make and model: Duncan DX4 - Registry model: [Duncan BABY HORNET DX4](https://openairdocs.org/model/duncan-baby-hornet-dx4) (registry code 0565810) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 1 - Engines: Volkswagen 65 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Robert M. Suarez - Airworthiness certificate: Special, Experimental (Special) - Departed: 1S6 - Airport: 1S6, Priest River Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: front; flight hours: 400 total, 200 in this make and model, 350 as pilot in command, 54 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 50 statute miles - Lowest ceiling: none - Temperature: 70 °F ## 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 19980921025669A](https://openairdocs.org/incident/19980921025669A), Sep 21, 1998: Priest River, ID, Substantial damage. Acft was experienceing aileron trouble, pilot added power, acft went up, crashed and was destroyed.(-23) after take off, Mr. Suarez stated that the aircraft… 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.