FTW98LA360

NTSB accident investigation · Cessna 170 · Boulder, CO · August 16, 1998

Accident · Minor injuriesLimited investigationFinal report
Date
August 16, 1998, 16:30 local (22:30 UTC)
Place
Boulder, CO
Injuries
3 minor
Damage
Substantial damage
Phase of flight
Landing
Aircraft
N2574VCessna 170
Weather
Visual (VMC) · Day
Status
Completed · report January 28, 2000
Report
Approved by Office Director
FAA report
19980816021079A
Case key
43768

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

The pilot's intentional ground loop and his inadequate compensation for the wind condition. A contributng factor was crosswinds.

Sequence of events

NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.

On ground/water encounter with terrain/waterLanding - flare/touchdown
Weather condition - crosswindFactor
Compensation for wind conditions - inadequatePilot in commandCause
Ground loop/swerve - intentionalPilot in commandCause
Terrain condition - runway

Analysis

As the pilot approached the airport for a full stop landing, he heard the pilot of another airplane, which was landing on runway 8 report that he had a tail wind during his landing sequence. The pilot 'noticed the wind sock on the east end of the runway was standing straight out in a direction that appeared to be 180 degrees.' The pilot landed on runway 26, but reported having difficulty keeping the airplane aligned with the centerline. He said 'I didn't feel at the time I stood any chance of gaining airspeed to execute a climb.' He performed a ground loop rather then go in the lake on the west end of the runway. One witness reported that immediately after the accident they noticed that the wind was coming from the northeast. The winds at the nearest reporting station, 9 nautical miles southeast, were 180 degrees and 13 knots at 1549 and at 1655, the winds were 150 degrees and 11 knots gusting to 20 knots.

Factual narrative

On August 16, 1998, approximately 1630 mountain daylight time, a Cessna 170, N2574V, was substantially damaged following an intentional ground loop initiated by the pilot at Boulder Municipal Airport, Boulder, Colorado. The private pilot and his two passengers received minor injuries. The airplane was being operated by the pilot under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the personal cross-country flight which originated from Ogallala, Nebraska, approximately 2 hours before the accident. A VFR flight plan had been filed.

The pilot reported that as he approached Boulder Municipal Airport (elevation 5,288 feet, density altitude 7,807 feet) for a full stop landing, he heard the pilot of another airplane which was landing on runway 8 report that he had a tail wind during his landing. The pilot said that he "noticed the wind sock on the east end of the runway was standing straight out in a direction that appeared to be 180 degrees." The pilot landed on runway 26, but reported having difficulty keeping N2574V aligned with the centerline. He said, "I immediately determined to execute a go around. I had trimmed nose up for landing so I was attempting to get the nose down but was also buffeted by very turbulent winds [coming] over the hangers to the south." The pilot said that he believed it was safer to perform a ground loop then to go in the lake at the west end of the runway. He said, "I didn't feel at the time I stood any chance of gaining airspeed to execute a climb."

One witness reported that immediately after the accident, they noticed that the wind was coming from the northeast. The winds at Jefferson County Airport (BJC), which is 9 nm southeast of Boulder Municipal Airport, were 180 degrees and 13 knots at 1549. At 1655, the winds at BJC were 150 degrees and 11 knots gusting to 20 knots.

Aircraft

Registration
N2574V
Reported as
Cessna 170
Category
Airplane
Serial number
18111
Airframe hours
5,688
Engine
Continental C145-2, 145 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Registered owner
Eric D. Twombly
Airworthiness certificate
Standard, Normal
Last inspection
Annual · August 6, 1997 · 126 hours before
Departed
OGA · Ogallala, NE
Destination
1V5
Flight plan
VFR
Airport
1V5 · Boulder Municipal, runway 26, 4,100 × 75 ft, asphalt

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
47
Certificate
Private
Airplane ratings
Single-engine land
Medical
Class 3, Valid Medical--w/ waivers/lim
Seat
Left
Flight hours
1,068 total · 1,025 in this make and model · 1,003 as pilot in command · 47 in the last 90 days · 30 in the last 30 days · 6 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Wind
150° at 11 knots, gusting 20
Visibility
50 statute miles
Lowest ceiling
20,000 ft broken
Temperature
81 °F, dew point 52 °F
Altimeter
30.00 inHg
Observed at
BJC, 9 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.