ANC20LA065

NTSB accident investigation · Cessna 180 · Anchorage, AK · July 5, 2020

Accident · No injuriesClass 3 · LimitedFinal report
Date
July 5, 2020, 11:15 local (19:15 UTC)
Place
Anchorage, AK
Injuries
2 uninjured
Damage
Substantial damage
Phase of flight
Landing
Aircraft
N9185TCessna 180
Defining event
Landing-flare/touchdown: Loss of control on ground
Weather
Visual (VMC) · Day
Status
Completed
Report
Approved by Office Director
Investigation class
Class 3
NTSB office
Alaska Regional Office
FAA report
20200705007549A
Case key
101546

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

On this page

Probable cause

The failure of the left float bottom due to corrosion, which resulted in a loss of control during the water landing.

Findings · 1

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Landing gear system: wheel/ski/floatAircraft › Aircraft systems · Fatigue/wear/corrosionCessna 180C: 1 caseAll aircraft: 48 casesProbable cause

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Analysis

According to the pilot, and corroborated by video capturing the accident, during a normal touchdown in a float-equipped airplane, the left float dug into the water and the airplane veered abruptly and nosed over. A postaccident examination revealed a large hole in the bottom of the left float just forward of the step. Corrosion was present around the hole and no impact signatures were present on the bottom of the float. The circumstances of the accident are consistent with a loss of control during the water landing due to the failure of the left float due to corrosion.

Factual narrative

On July 5, 2020, about 1115 Alaska daylight time, a Cessna 180C airplane, N9185T, sustained substantial damage when it was involved in an accident near Anchorage, Alaska. The private pilot and one passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, they were returning from a remote lake to Lake Hood Airport (PALH) in the float-equipped airplane. The pilot stated that the departure was normal, with about 10 to 12 mph of wind on the lake, creating a light chop on the water's surface. Upon touchdown at PALH, the left float dug into the water and the airplane veered abruptly and nosed over. He stated that they quickly exited the sinking wreckage. A video captured the accident sequence and revealed that the airplane touched down on about the step of the floats before abruptly veering to the left. The right wing contacted the water and the airplane veered back to the right, and then to the left, before the airplane nosed over. A postaccident examination of the left float revealed a large hole in the bottom of the float just forward of the step. (See Figure 1.) Corrosion was present around the hole and no impact signatures were present on the bottom of the float. Figure 1 - Accident airplane at accident site, hole visible in left float. Photo courtesy of KTVA.

Aircraft

Registration
N9185T
Reported as
Cessna 180
Category
Airplane
Serial number
50685
Built
1960
Airframe hours
5,608
Engine
Continental O-470R, 230 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Airworthiness certificate
Standard, Normal
Last inspection
Annual · July 30, 2019
Departed
LHD · Anchorage, AK
Destination
LHD · Anchorage, AK
Airport
LHD · Lake Hood

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
81
Injuries
None
Certificate
Private
Airplane ratings
Single-engine land, Single-engine sea
Medical
BasicMed, Unknown
Seat
Left
Restraint
3-point
Flight hours
1,500 total · 1,441 in this make and model · 1,500 as pilot in command · 7 in the last 90 days · 7 in the last 30 days

Weather

Conditions
Visual (VMC) · Day
Wind
220° at 13 knots, gusting 21
Visibility
10 statute miles
Lowest ceiling
10,000 ft broken
Temperature
64 °F, dew point 52 °F
Observed at
LHD

Docket · 2

The files NTSB released with the investigation on January 19, 2022, on NTSB’s docket system: statements, records, photos and specialists’ reports. 1.6 MB in all.

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.