LAX98LA084

NTSB accident investigation · Let Blanik L-13 · Prescott Valley, AZ · January 25, 1998

Accident · No injuriesLimited investigationFinal report
Date
January 25, 1998, 12:00 local (19:00 UTC)
Place
Prescott Valley, AZ
Injuries
1 uninjured
Damage
Substantial damage
Phase of flight
Takeoff
Aircraft
N3463Let Blanik L-13
Weather
Visual (VMC) · Day
Status
Completed · report February 15, 2001
Report
Approved by Office Director
FAA report
19980125003549A
Case key
30031

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 failure of the ground crew to correctly attach the tow bridle, which resulted in the pilot's loss of directional control.

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.

Loss of control - on ground/waterTakeoff - roll/run
Glider launch/tow equipment - disconnectedCause
Glider/tow release - improperGround personnelCause
Directional control - not possiblePilot in command
On ground/water collision with objectTakeoff - roll/run
Object - vehicle
Object - pole

Analysis

The glider uses two attachment points on its bridle, one on either side of the fuselage, and has a single retractable wheel in the center of the fuselage. The left side bridle attachment point for the glider became unattached as the glider began the winch tow. The asymmetrical force then pulled the glider to the left, and the left wing struck a parked truck. The glider then proceeded in a sharp angle away from the runway towards the windsock pole, still under tow on only the right side and still accelerating. The glider launched into the air and struck the top of the windsock pole with the inboard portion of the right wing. The pilot reported that he then pulled the release to disconnect the tow wire from the glider. The right wingtip then struck the ground and the glider swung around approximately 270 degrees as the fuselage and tail struck the ground and came to a stop. According to an FAA inspector, the bridle was incorrectly attached at the time of the accident by the ground crew.

Factual narrative

On January 25, 1998, at 1200 hours mountain standard time, a Let Blanik L-13, N3463, veered off the runway and collided with parked vehicles during a winch launch at the Coyote Run Gliderport, Prescott Valley, Arizona. The glider sustained substantial damage and the commercial pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed at the time of the accident and no flight plan was filed for the intended local area personal flight.

In his report, the pilot explained that the Blanik L-13 uses two attachment points on its tow bridle, instead of the usual single attachment point, with one attach point on either side of the fuselage about half way up the side. The glider has a single retractable wheel in the center of the fuselage. He reported that during this particular launch, the left hook of the bridle became unattached almost immediately as the glider lurched forward under the winch tow. With only the right hook attached, "the one attachment point now worked as a lever, rotating the glider about the center wheel, and resulting in the glider being pulled off to the left side of the runway as it shot forward." The pilot further stated that before he had time to react and pull the release, the left wingtip of the glider struck the tailgate of a pickup truck parked off the left side of the runway, and approximately 6 feet of the outer portion of the wingtip separated at the leading edge. The glider then proceeded in a sharp angle away from the runway towards the windsock pole still under tow on only the right side and still accelerating. The glider then launched into the air and struck the top of the windsock pole with the inboard portion of the right wing. The pilot reported that at that time he pulled the release to disconnect the tow wire from the glider. The right wingtip then struck the ground and the glider swung around approximately 270 degrees as the fuselage and tail struck the ground and came to a stop.

According to a Federal Aviation Administration inspector from the Scottsdale Flight Standards District Office, the bridle was incorrectly attached at the time of the accident by the ground crew.

Aircraft

Registration
N3463
Reported as
Let Blanik L-13 (BLANIK L-1)
Category
Glider
Serial number
173921
Airframe hours
2,017
Engine
unknown
Damage
Substantial damage
Flight
Personal · Part 91
Registered owner
Prescott Soaring Association
Airworthiness certificate
Standard, Normal
Last inspection
Annual · June 1, 1997 · 85 hours before
Airport
Coyote Run Glider Port, runway 21, 2,500 × 10 ft, dirt

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
39
Certificate
Commercial
Medical
Unknown
Seat
Front
Flight hours
223 total · 19 in this make and model · 199 as pilot in command · 1 in the last 90 days

Weather

Conditions
Visual (VMC) · Day
Wind
290° at 5 knots
Visibility
50 statute miles
Temperature
61 °F
Altimeter
29.00 inHg

FAA reports on this event · 1

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

Other investigations on N3463 · 1

Matched to the same aircraft by N-number and date.