# NTSB GAA17CA526: Cessna 172, N5703A, Coolin, ID, September 10, 2017 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Data collection · Final report - Date: September 10, 2017, 14:44 local (21:44 UTC) - Place: Coolin, ID - Coordinates: 48.518611, -116.822219 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=48.5186&lon=-116.8222&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Loss of lift](https://openairdocs.org/ntsb-events/500) - Highest injury: Serious injuries - Injuries: 1 serious, 3 uninjured - Status: Completed, report November 27, 2017 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA/ FSDO - NTSB case key (mKey): 95979 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA17CA526 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95979/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95979 - Page: https://openairdocs.org/ntsb/GAA17CA526 ## Probable cause The pilot's decision to take off in high-density altitude and gusting quartering tailwind conditions, which resulted in a loss of lift and an inability to gain altitude during the initial climb. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Cessna 172, 19 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=2072402), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Performance/control parameters: altitude](https://openairdocs.org/ntsb-findings/01062012): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Cessna 172, 8 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=2072402), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md) - [Wind: tailwind](https://openairdocs.org/ntsb-findings/03034015): Environmental issues › Conditions/weather/phenomena · Decision related to condition; cases with it: [Cessna 172, 3 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md?model=2072402), [All aircraft, 594 cases](https://openairdocs.org/ntsb-findings/03034015/cases.md) - [Wind: crosswind](https://openairdocs.org/ntsb-findings/03034040): Environmental issues › Conditions/weather/phenomena · Decision related to condition; cases with it: [Cessna 172, 3 cases](https://openairdocs.org/ntsb-findings/03034040/cases.md?model=2072402), [All aircraft, 1,008 cases](https://openairdocs.org/ntsb-findings/03034040/cases.md) - [Wind: gusts](https://openairdocs.org/ntsb-findings/03034045): Environmental issues › Conditions/weather/phenomena · Decision related to condition; cases with it: [Cessna 172, 2 cases](https://openairdocs.org/ntsb-findings/03034045/cases.md?model=2072402), [All aircraft, 1,199 cases](https://openairdocs.org/ntsb-findings/03034045/cases.md) - [Temp/humidity/pressure: high density altitude](https://openairdocs.org/ntsb-findings/03031020): Environmental issues › Conditions/weather/phenomena · Decision related to condition; cases with it: [Cessna 172, 1 case](https://openairdocs.org/ntsb-findings/03031020/cases.md?model=2072402), [All aircraft, 278 cases](https://openairdocs.org/ntsb-findings/03031020/cases.md) - [Object/animal/substance: tree(s)](https://openairdocs.org/ntsb-findings/03022020): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Cessna 172, 8 cases](https://openairdocs.org/ntsb-findings/03022020/cases.md?model=2072402), [All aircraft, 933 cases](https://openairdocs.org/ntsb-findings/03022020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Other weather encounter](https://openairdocs.org/ntsb-events/400); cases with it: [Cessna 172, 4 cases](https://openairdocs.org/ntsb-events/400/sequence.md?model=2072402), [All aircraft, 1,127 cases](https://openairdocs.org/ntsb-events/400/sequence.md) - [Initial climb: Loss of lift](https://openairdocs.org/ntsb-events/500) (defining event); cases with it: [Cessna 172, 2 cases](https://openairdocs.org/ntsb-events/500/sequence.md?model=2072402), [All aircraft, 252 cases](https://openairdocs.org/ntsb-events/500/sequence.md) - [Initial climb: Abnormal runway contact](https://openairdocs.org/ntsb-events/090); cases with it: [Cessna 172, 4 cases](https://openairdocs.org/ntsb-events/090/sequence.md?model=2072402), [All aircraft, 1,506 cases](https://openairdocs.org/ntsb-events/090/sequence.md) - [Landing-landing roll: Runway excursion](https://openairdocs.org/ntsb-events/300); cases with it: [Cessna 172, 10 cases](https://openairdocs.org/ntsb-events/300/sequence.md?model=2072402), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) ## Analysis The pilot reported that he completed a normal landing to the south at a grass airstrip near a lake that was surrounded by 75-ft-tall pine trees. He added that he and his passengers ate lunch at the airstrip, and during that time, he noticed "mostly calm" wind with an "occasional gust from the south." The pilot further reported that, due to the runway gradient, he decided to take off downhill to the north because the wind sock was indicating a calm wind. He reported that, during the soft field takeoff, the takeoff roll was normal, but that, about 100 ft above ground level, he noticed that the "climb had slowed" and the "airspeed was dropping." The pilot lowered the nose, the airplane "descended quickly," and then touched down on the runway with about 30 ft remaining. Subsequently, the airplane overran the runway, crossed a road, and impacted a dumpster and trees. The fuselage and both wings sustained substantial damage. The pilot reported that the airplane was 25 lbs under maximum gross weight. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. An automated weather observation station (AWOS) 13 nautical miles from the accident site, reported, about the time of the accident, wind from 240° at 6 knots. A review of four hourly AWOS recordings, south and east of the accident site, around the time of the accident, revealed that the wind was variable from the southwest to west at 5 to 10 knots, gusting 15 to 18 knots. The pilot reported that the takeoff was on runway 33. The calculated density altitude was 3,700 ft. According to the Federal Aviation Administration (FAA) density altitude Koch Chart, the airplane would have likely experienced a 32% decrease in the normal climb rate and a 50% increase in the normal takeoff distance. The FAA's Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25B, contained a section titled, "Effect of Obstructions on Wind," which stated in part: "Another atmospheric hazard exists that can create problems for pilots. Obstructions on the ground affect the flow of wind and can be an unseen danger. Ground topography and large buildings can break up the flow of the wind and create wind gusts that change rapidly in direction and speed. These obstructions range from man-made structures, like hangars, to large natural obstructions, such as mountains, bluffs, or canyons. It is especially important to be vigilant when flying in or out of airports that have large buildings or natural obstructions located near the runway. The intensity of the turbulence associated with ground obstructions depends on the size of the obstacle and the primary velocity of the wind. This can affect the takeoff and landing performance of any aircraft and can present a very serious hazard." It is likely that, during the initial climb in high-density altitude conditions, the airplane encountered a quartering tailwind gust as the airplane climbed above thetrees, which resulted in a loss of lift and an inability to gain altitude during the initial climb. ## Factual narrative The pilot reported that he completed a normal landing to the south at a grass airstrip, near a lake and surrounded by 75 ft. tall pine trees. He added that he and his passengers ate lunch at the airstrip, and during that time, he noticed "mostly calm" wind with an "occasional gust from the south." The pilot further reported that, due to the runway gradient, he decided to takeoff downhill to the north, as the wind sock was indicating a calm wind. During the soft field takeoff, he reported that the take-off roll was normal, but about 100 ft. above ground he noticed that the "climb had slowed" and the "airspeed was dropping." The pilot lowered the nose, the airplane "descended quickly," and touched down on the runway with about 30 ft. remaining. Subsequently, the airplane overran the runway, crossed a road, and impacted a dumpster and trees. The fuselage and both wings sustained substantial damage. The pilot reported that the airplane was 25 lbs. under maximum gross weight. The pilot did not report that there were any preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. An automated weather observation station (AWOS), about the time of the accident, 13 nautical miles from the accident site, reported wind from 240° at 6 knots. A review of four, hourly AWOSs, south and east of the accident site, around the time of the accident, recorded wind variable from the southwest to westerly direction, at 5 to 10 knots, gusting 15 to 18 knots. The pilot reported that the takeoff was on runway 33. The calculated density altitude was 3,700 ft. According to the Federal Aviation Administration density altitude Koch Chart, the airplane would have likely experienced a 32% decrease to the normal climb rate, and a 50% increase to the normal takeoff distance. The Federal Aviation Administration's Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25B, contains a section titled "Effect of Obstructions on Wind" which stated in part: "Another atmospheric hazard exists that can create problems for pilots. Obstructions on the ground affect the flow of wind and can be an unseen danger. Ground topography and large buildings can break up the flow of the wind and create wind gusts that change rapidly in direction and speed. These obstructions range from man-made structures, like hangars, to large natural obstructions, such as mountains, bluffs, or canyons. It is especially important to be vigilant when flying in or out of airports that have large buildings or natural obstructions located near the runway. The intensity of the turbulence associated with ground obstructions depends on the size of the obstacle and the primary velocity of the wind. This can affect the takeoff and landing performance of any aircraft and can present a very serious hazard." ## Aircraft - Registration: [N5703A](https://openairdocs.org/deregistered/N5703A-2020-05-01), registration cancelled 2020-05-01, S/N 28303, built 1956 (OpenAirDocs) - Reported make and model: CESSNA 172 (UNDESIGNAT) - Registry model: [Cessna 172](https://openairdocs.org/model/cessna-172) (registry code 2072402) (OpenAirDocs) - Registry engine: [Continental 0-300 series](https://openairdocs.org/engine/continental-0-300-series) (registry code 17022, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 28303 - Year built: 1956 - Airframe hours: 2810 - Engines: CONT MOTOR O-300 145 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 8, 2017 - Departed: 66S, Coolin, ID - Destination: SFF, SPOKANE, WA - Airport: 66S, Cavanaugh Bay, runway 33, 3,100 × 120 ft, grass/turf - Equipment: Stall warning system, Electronic flight bag or handheld device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 63; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review April 5, 2016; seat: left; restraint: 4-point; flight hours: 325 total, 176 in this make and model, 289 as pilot in command, 21 in the last 90 days, 9 in the last 30 days, 3 in the last 24 hours - Pilot-rated passenger; age 71; injuries: none; private; last flight review January 1, 1987; seat: right; restraint: 4-point; flight hours: 1,008 total, 115 in this make and model, 945 as pilot in command, 0 in the last 90 days, 0 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 37 °F - Altimeter: 30.20 inHg - Observed at: KSZT, 16 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 20170910011269A](https://openairdocs.org/incident/20170910011269A), Sep 10, 2017: Cessna 172, Coolin, ID, Substantial damage. Pilot attempted take off on runway 33. Pilot stated when aircraft was approximately 100' AGL, the aircraft stopped climbing and decended back towards the… ## Docket (3 files) The files NTSB released with the investigation on November 6, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95979. 888 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 497 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457751&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Meteorological Information (item 2, .PDF, 183 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457752&FileExtension=.PDF&FileName=Meteorological%20Information-Master.PDF - Accident Photo (Courtesy of FAA) (item 3, .PDF, 1 photo, 207 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457753&FileExtension=.PDF&FileName=Accident%20Photo%20(Courtesy%20of%20FAA)-Master.PDF 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.