Aircraft Accident/Incident Report

Boulder, Colorado 80301
Saturday, February 6, 2010 13:27 MST

NTSB Narrative Summary Released at Completion of Accident

While conducting glider-tow operations, the right wing of a Piper PA-25 was struck at a 90 degree angle by a Cirrus SR20. Analysis of the radar information, the flight condition of both airplanes, and the pilots' visibility in their respective cockpit configurations, suggests that until just prior to the impact, the Piper would have been located below the horizon and against the background of the surrounding terrain and city, between the 10 and 11 o’clock position of the Cirrus pilot. The Piper remained in this same relative position in the windscreen of the Cirrus pilot for the entire duration of its 7 minute flight. The Cirrus would have been above the horizon, against the white overcast sky, in about the 1 to 2 o’clock position of the Piper pilot. The Cirrus would have only appeared in this position after the Piper pilot completed the last turn and was headed to the west, which would have been (at most) the last 3 minutes of the flight. Visual meteorological conditions existed at the time of the accident with an overcast layer and visibility of 8 miles. The overcast sky conditions likely made it difficult for the Piper pilot to detect the primarily white-colored Cirrus. The lack of maneuvering, as observed by the glider pilot prior to the accident, suggests that neither the pilot of the Cirrus nor the pilot of the Piper observed the other airplane prior to the accident. If the Piper pilot had observed the Cirrus prior to the impact, his ability to maneuver to avoid an impact would have been severely limited due to the glider in tow. A postaccident examination of the engine and flight control systems on both airplanes revealed no mechanical anomalies that would have prevented either pilot from maneuvering to avoid an impact. Medical and pathological examination of both pilots revealed no medical or toxicological issues that would have precluded either pilot from operating their airplane in a safe manner prior to the accident.

NTSB Probable Cause Narrative

The failure of both pilots to see and avoid the other resulting in a midair collision. Contributing to the accident was the lack of perceived visual relative motion of the Piper and the Cirrus to the pilot of each airplane, the terrain background, and the overcast weather conditions making it difficult for either pilot to visually acquire the other aircraft.

Event Information

Type of Event Accident
Event Date 2/6/2010
Event Day of the Week Saturday
Time of Event 1327
Event Time Zone Mountain Standard Time
Event City Boulder
Event State COLORADO
Event Country --
Zipcode of the event site 80301
Event Date Year 2010
Event Date Month 2
MidAir Collision Indicator Yes
On Ground Collision occurred ? --
Event Location Latitude 400436N
Event Location Longitude 1051614W
Event Location Airport --
Event Location Nearest Airport ID --
Indicates whether the acc/inc occurred off or on an airport Off Airport/Airstrip
Distance from airport in statute miles --
Degrees magnetic from airport --
Airport Elevation --
Weather Briefing Completeness --
Investigator's weather source Weather Observation Facility
Time of the weather observation 1247 Mountain Standard Time
Direction of event from weather observation facility (degrees) --
Weather Observation Facility ID KBJC
Elevation of weather observation facility 5673
Distance of event from weather observation facility (units?) --
Time Zone of the weather observation MST
Lighting Conditions Day
Lowest Ceiling Height 12000
Lowest Non-Ceiling Height 8000
Sky/Lowest/Cloud Conditions Scattered
Sky Condition for Lowest Ceiling Overcast
Visibility Runway Visual Range (Feet) --
Visibility Runway Visual Value (Statute Miles) --
Visibility (Statute Miles) 8
Air Temperature at event time (in degrees celsius) 4
Dew Point at event time (in degress fahrenheit) -6
Wind Direction (degrees magnetic) --
Variable Wind Indicator --
Wind Speed (knots) --
Wind Velocity Indicator Calm
Wind Gust Indicator --
Wind Gust (knots) --
Altimeter Setting at event time (in. Hg) 29.89
Density Altitude (feet) --
Intensity of Precipitation --
METAR weather report --
Event Highest Injury Fatal
On Ground, Fatal Injuries --
On Ground, Minor Injuries --
On Ground, Serious Injuries --
Injury Total Fatal 3
Injury Total Minor --
Injury Total None 3
Injury Total Serious --
Injury Total All 3
Investigating Agency NTSB
NTSB Docket Number (internal use) 27971
NTSB Notification Source Mile High Gliders
NTSB Notification Date --
NTSB Notification Time --
Fiche Number and/or location -used to find docket information --
Date of most recent change to record Apr 28 2011 11:41AM
User who most recently changed record rows
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft #2

Aircraft #3

Aircraft Registration Number N8718L N825BC N2472W
NTSB Number CEN10FA115A CEN10FA115B CEN10FA115C
Missing Aircraft Indicator -- -- --
Federal Aviation Reg. Part Part 91: General Aviation Part 91: General Aviation Part 91: General Aviation
Type of Flight Plan filed None None None
Flight plan Was Activated? No No No
Damage Substantial Substantial None
Aircraft Fire None Ground and In-flight None
Aircraft Explosion None None None
Aircraft Manufacturer's Full Name PIPER CIRRUS DESIGN CORP SCHWEIZER
Aircraft Model PA-25-235 SR20 SGS 2-32
Aircraft Series Identifier -- -- --
Aircraft Serial Number 17256378 1655 47
Certified Max Gross Weight -- -- 1340
Aircraft Category Airplane Airplane Glider
Aircraft Registration Class -- -- --
Aircraft is a homebuilt? No No No
Flight Crew Seats -- -- --
Cabin Crew Seats -- -- --
Passenger Seats -- -- --
Total number of seats on the aircraft 1 4 3
Number of Engines 1 1 0
Fixed gear or retractable gear Fixed Fixed Fixed
Aircraft, Type of Last Inspection Continuous Airworthiness Annual Annual
Date of Last Inspection Feb 1 2010 12:00AM Apr 8 2009 12:00AM Aug 24 2009 12:00AM
Airframe hours since last inspection -- -- --
Airframe Hours 9929 319 6107
ELT Installed No Yes No
ELT Activated No Unknown No
ELT Aided Location of Event Site No No No
ELT Type -- -- --
Aircraft Owner Name Mile High Gliding Inc MATTHEWS ROBERT L MILE HIGH GLIDING INC
Aircraft Owner Street Address 5534 Independence Road 6725 WHALEY DR 5534 INDEPENDENCE RD
Aircraft Owner City Boulder BOULDER BOULDER
Aircraft Owner State CO CO CO
Aircraft Owner Country USA USA USA
Aircraft Owner Zipcode 80301 80303-4328 80301-3070
Operator is an individual? No Yes No
Operator Name Mile High Gliding Inc MATTHEWS ROBERT L MILE HIGH GLIDING INC
Operator Same as Owner? Yes Yes Yes
Operator Is Doing Business As -- -- --
Operator Address Same as Owner? Yes Yes Yes
Operator Street Address 5534 Independence Road 6725 WHALEY DR 5534 INDEPENDENCE RD
Operator City Boulder BOULDER BOULDER
Operator State CO CO CO
Operator Country USA USA USA
Operator Zip code 80301 80303-4328 80301-3070
Operator Code -- -- --
Owner has at least one certificate None None None
Other Operator of large aircraft? No No No
Certified for Part 133 or 137 Operation -- -- --
Operator Certificate Number -- -- --
Indicates whether an air carrier operation was scheduled or not -- -- --
Indicates Domestic or International Flight -- -- --
Operator carrying Pax/Cargo/Mail -- -- --
Type of Flying (Per_Bus / Primary) Glider Tow Personal Glider Tow
Second Pilot on Board No No No
Departure Point Same as Event No No No
Departure Airport Code KBDU KEIK KBDU
Departure City Boulder Erie Boulder
Departure State CO CO CO
Departure Country USA USA USA
Departure Time 1320 1300 1320
Departure Time Zone MST MST MST
Destination Same as Local Flt dest & departure same, accident can occur anywhere dest & departure same, accident can occur anywhere dest & departure same, accident can occur anywhere
Destination Airport Code KBDU KEIK KBDU
Destination City Boulder Erie Boulder
Destination State CO CO CO
Destination Country USA USA USA
Specific Phase of Flight -- -- --
Report sent to ICAO? -- -- --
Evacuation occurred -- -- --
Date of most recent change to record Jan 25 2011 10:06AM Jan 25 2011 10:06AM Jan 25 2011 10:33AM
User who most recently changed record kaij kaij kaij
Since inspection or accident Last Inspection Last Inspection Last Inspection
Event Location Runway Number and Location N/A N/A N/A
Runway Length -- -- --
Runway Width -- -- --
Sight Seeing flight No No No
Air Medical Flight No No No
Medical Flight -- -- --