# NTSB SEA99LA079: Snow S2C, N1665S, Paul, ID, June 1, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 1, 1999, 12:00 local (18:00 UTC) - Place: Paul, ID - Coordinates: 42.659557, -113.809951 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=42.6596&lon=-113.8100&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report August 3, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46607 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA99LA079 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46607/pdf - Page: https://openairdocs.org/ntsb/SEA99LA079 ## Probable cause The pilot's inaccurate weight and balance calculations, and his delay in jettisoning the load which resulted in his failure to clear rising terrain. Contributing to the accident was the high density altitude, and the pilot's intentional operation with known deficiencies in equipment. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with terrain/water, takeoff - aircraft weight and balance - inaccurate, pilot in command (cause) - load jettison - delayed, pilot in command (cause) - altitude - inadequate, pilot in command (cause) - terrain condition - rising - operation with known deficiencies in equipment - intentional, pilot in command (contributing factor) - weather condition - high density altitude (contributing factor) ## Analysis The pilot reported that after the airplane lifted off, it was not flying as well as it had on the previous six flights that morning. The pilot immediately opened the emergency dump which also controls the rate of application. The pilot reported that as he flipped the metal tab out of the way of the dump handle, the tab would not flip clear of the handle because of interference with the seat frame. The pilot was aware of this problem, however, he stated that he could hold the stop up with one finger and force the handle around the stop. The airplane continued to fly in ground effect as the pilot continued to try to dump the load. About one mile off the end of the airstrip, the airplane collided with a slight rise in the terrain. The pilot stated that he thought that he could have cleared the rise if he could have dumped the load more quickly. The type certificate data sheet for this aircraft indicates a gross weight of 4,400 pounds. The pilot reported that he was not aware of the requirement, and had not demonstrated the maximum set gross weight for the conditions to the FAA per Part 137 certification. The pilot reported that he estimated the weight of the load based on visual volume that had been previously weighed (approximately 1,000 to 1,100 pounds). The density altitude was estimated and determined to be approximately 5,684 feet at the time of the accident which utilized the pilot's estimated temperature. The weather reporting facility closest to the accident site reported a temperature 10 degrees warmer than the pilot's estimate. Utilizing the weather reporting facility, the density altitude would have been about 6,277 feet. ## Factual narrative On June 1, 1999, at 1200 mountain daylight time, a Snow S2C, N1665S, registered to and operated by Mustang Aviation as a 14 CFR Part 137, aerial application flight, collided with the terrain shortly after takeoff from a private airstrip near Paul, Idaho. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local flight. The airplane was substantially damaged and the commercial pilot, the sole occupant, was not injured. During a telephone interview and subsequent written statement, the pilot reported that this was the seventh flight of the day, and that the load (approximately 1,000 to 1,100 pounds of dry fertilizer), was based on visual volume that had been previously weighed the day before. The pilot reported that he had flown 18 flights the day before under similar temperature conditions (62 degrees F) and load volume without incident. The pilot reported that after the airplane lifted off, he felt that the airplane was not flying as well as it had on the previous flights that day. The pilot stated that he immediately opened the emergency dump which also controls the rate of application. The pilot reported that as he flipped the metal tab out of the way of the dump handle, the tab would not flip clear of the handle because of interference with the seat frame. The pilot reported that at the rate that was set for the application, it would take about three miles to empty the hopper. The pilot reported that he was aware of this problem, but he could hold the stop up with one finger and force the handle around the stop. The pilot reported that he was flying the airplane in ground effect and trying to move the dump handle around the stop, when the airplane collided with a rise in the terrain. The main landing gear contacted the ground first, followed by the left wing. The main landing gear collapsed and the airplane came to rest 90 degrees from the direction of travel, and about 50 yards from the initial impact point. The accident site was about one mile from the end of the airstrip. The pilot stated that if he could have dumped more of the load more quickly, he probably could have flown over the rising terrain. The type certificate data sheet for this aircraft's serial number indicates a gross weight of 4,400 pounds. The pilot reported that he was not aware of the requirement, and had not demonstrated the maximum set gross weight for the conditions to the Federal Aviation Administration per Part 137 certification. A Federal Aviation Administration Inspector from the Boise, Idaho, Flight Standards District Office, responded to the accident site and documented the aircraft's emergency dump system. The inspector reported that the design of the system in the aircraft is different than the manufacturers drawings. At 1153, the Twin Falls airport, located 36 miles west of Paul, was reporting a temperature of 72 degrees F, and 29.81" Hg. The elevation at Twin Falls is 4,151 feet. Utilizing the temperature and pressure altitude from Twin Falls, the density altitude at Paul would have been approximately 6,277 feet. Utilizing the pilot's estimated temperature of 62 degrees, the density altitude would have been approximately 5,684 feet. The elevation at Paul is 4,300 feet. ## Aircraft - Registration: [N1665S](https://openairdocs.org/deregistered/N1665S-2013-04-30), registration cancelled 2013-04-30, S/N 1238C, built 1964 (OpenAirDocs) - Reported make and model: Snow S2C - Registry model: [Snow S2C](https://openairdocs.org/model/snow-s2c) (registry code 8380206) (OpenAirDocs) - Registry engine: [Pratt & Whitney R-985 series](https://openairdocs.org/engine/pratt-whitney-r-985-series) (registry code 52008, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 1238C - Engines: P&W R-985 450 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Spaulding Aerial Application - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, January 3, 1999, 20 hours before ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 456 total, 20 in this make and model, 384 as pilot in command, 83 in the last 90 days, 56 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 270° at 4 knots - Visibility: 15 statute miles - Lowest ceiling: none - Temperature: 63 °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 19990601005939A](https://openairdocs.org/incident/19990601005939A), Jun 1, 1999: Ayres S2C, Paul, ID, Substantial damage. Acft was departig private strip when acft lost lift. Pilot dumped most of the liquid fertilizer but crashed in sage brush. (-23) pilot had been spreading… ## Other investigations on N1665S (1) 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 SEA83LA136](https://openairdocs.org/ntsb/SEA83LA136), Jun 3, 1983: Snow S2C (N1665S), Hepner, OR, substantial damage 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.