- Date
- November 7, 2020, 12:51 local (20:51 UTC)
- Place
- Clayton, CA · Mt. Diablo State Park
- Injuries
- 2 serious
- Phase of flight
- Maneuvering
- Defining events
- Maneuvering: Midair collisionManeuvering: Midair collision
- Weather
- Visual (VMC) · Day
- Status
- Completed
- Report
- Approved by Office Director
- Investigation class
- Class 4 - Basic report with no Prelim publish
- NTSB office
- Western Pacific Region
- Parties
- FAA
- FAA reports
- 20201107020572A20201107020582A
- Case key
- 102252
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 both pilots of each glider to see an avoid one another while maneuvering, which resulted in a mid-air collision.
Findings · 4
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.
N18MA · Schleicher ASW20C
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.
N18MA · Schleicher ASW20C
N81KP · Schleicher ASW27
Analysis
The pilot of an ASW-20C glider reported that, while following lift under cumulus clouds, he observed another glider, an ASW-27 traversing from right to left. He entered into a steep dive in an attempt to avoid the other glider, however, the ASW-20C impacted the ASW-27 glider. Following the collision, the ASW-20C entered a steep descent and rolled inverted before the pilot elected to bail out and parachute to safety. The ASW-20C pilot added that the glider was equipped with a FLARM collision system, and prior to the collision, did not receive any alerts of additional traffic. The pilot of an ASW-27 glider reported that while maneuvering, another glider suddenly appeared to his left and followed by a collision. The pilot stated that his glider immediately entered a descent and was out of control. The pilot of the ASW-27 subsequently bailed out and parachuted to safety. The glider was equipped with a FLARM collision system but was inoperative awaiting an annual software update. The ASW-20C glider sustained substantial damage to the left wing. The ASW-27 glider sustained substantial damage to the left wing and aft fuselage. Both glider pilots reported that there were no preaccident mechanical failures or malfunctions with the gliders that would have precluded normal operation.
Aircraft · 2
- Registration
- N18MA
- Reported as
- Schleicher ASW20C
- Category
- Glider
- Serial number
- 20844
- Built
- 1986
- Airframe hours
- 1,431.7
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Registered owner
- Paul N Loewenstine
- Airworthiness certificate
- Special, Experimental (Special)
- Last inspection
- Annual · February 22, 2020
- Departed
- C83 · Byron, CA
- Equipment
- ADS-B, Satellite tracking device, Data recorder, Electronic flight bag or handheld device
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.
- Registration
- N81KP
- Reported as
- Schleicher ASW27
- Category
- Glider
- Serial number
- 27041
- Built
- 1997
- Airframe hours
- 4,245
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Registered owner
- Laurance J Suter
- Airworthiness certificate
- Standard, Normal; Standard, Utility
- Last inspection
- Annual · March 3, 2020
- Departed
- C83 · Byron, CA
- Equipment
- Handheld GPS
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 · 2
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot, aircraft N18MA
- Age
- 71
- Injuries
- Minor
- Certificate
- Private
- Airplane ratings
- Single-engine land
- Instrument ratings
- Airplane
- Medical
- BasicMed, With waivers/limitations
- Last flight review
- February 7, 2020
- Seat
- Single
- Restraint
- 4-point
- Flight hours
- 1,847 total · 186 in this make and model · 1,800 as pilot in command · 31 in the last 90 days · 10 in the last 30 days · 5 in the last 24 hours
- Role
- Pilot, aircraft N81KP
- Age
- 73
- Injuries
- Serious
- Certificate
- Commercial
- Airplane ratings
- Single-engine land
- Instrument ratings
- Airplane
- Medical
- BasicMed, With waivers/limitations
- Last flight review
- February 9, 2020
- Seat
- Center
- Restraint
- 4-point
- Flight hours
- 2,794 total · 2,723 as pilot in command · 31 in the last 90 days · 7 in the last 30 days · 1 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- Variable at 5 knots
- Visibility
- 10 statute miles
- Temperature
- 61 °F, dew point 32 °F
- Altimeter
- 29.73 inHg
- Turbulence
- Moderate
- Observed at
- KLVK, 11 nm away
Docket · 4
The files NTSB released with the investigation on August 20, 2021, on NTSB’s docket system: statements, records, photos and specialists’ reports. 7.3 MB in all.
FAA reports on this event · 2
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.