Air carrier-mdt and an small aircraft have near midair collision.

Attributes
ACN	88178
Time
Date	198806
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : den
State Reference	CO
Altitude	msl bound lower : 15500 msl bound upper : 15500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Transport, Low Wing, 2 Turboprop Eng
Flight Phase	climbout : intermediate altitude
Route In Use	enroute airway : j60
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft, High Wing, 1 Eng, Retractable Gear
Flight Phase	cruise other
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 160 flight time total : 10000
ASRS Report	88178
Person 2
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	conflict : nmac
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 100 vertical : 0
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were climbing wbound on J60 from den to aspen. Approximately 20 mi west of den, climbing through approximately 15500' on our way to FL200, IFR under departure control for stapleton airport, we came within 100', and probably much less, of colliding with a VFR small aircraft. The aircraft came at us from out left side at a 90 degree angle to our flight path. We were in VFR conditions, but in spite of careful observation, never saw the aircraft until he was within 100' and converging. The small aircraft was in level flight and not in contact with any controling body. He evidently saw us at the last moment and swerved behind us passing very close, possibly less than 100'. I called departure control and they advised me they, in fact, did have a VFR target at our location. No advisory was issued. We should have collided except for pure luck. Both aircraft were legal to be in that airspace. We were IFR, he was in uncontrolled VFR. It would seem 15500' and uncontrolled within 20 mi of the fifth busiest airport is asking for a midair. The airspace is much too unrestricted.

Original NASA ASRS Text

Title: ACR-MDT AND AN SMA HAVE NMAC.

Narrative: WE WERE CLBING WBOUND ON J60 FROM DEN TO ASPEN. APPROX 20 MI W OF DEN, CLBING THROUGH APPROX 15500' ON OUR WAY TO FL200, IFR UNDER DEP CTL FOR STAPLETON ARPT, WE CAME WITHIN 100', AND PROBABLY MUCH LESS, OF COLLIDING WITH A VFR SMA. THE ACFT CAME AT US FROM OUT LEFT SIDE AT A 90 DEG ANGLE TO OUR FLT PATH. WE WERE IN VFR CONDITIONS, BUT IN SPITE OF CAREFUL OBSERVATION, NEVER SAW THE ACFT UNTIL HE WAS WITHIN 100' AND CONVERGING. THE SMA WAS IN LEVEL FLT AND NOT IN CONTACT WITH ANY CTLING BODY. HE EVIDENTLY SAW US AT THE LAST MOMENT AND SWERVED BEHIND US PASSING VERY CLOSE, POSSIBLY LESS THAN 100'. I CALLED DEP CTL AND THEY ADVISED ME THEY, IN FACT, DID HAVE A VFR TARGET AT OUR LOCATION. NO ADVISORY WAS ISSUED. WE SHOULD HAVE COLLIDED EXCEPT FOR PURE LUCK. BOTH ACFT WERE LEGAL TO BE IN THAT AIRSPACE. WE WERE IFR, HE WAS IN UNCTLED VFR. IT WOULD SEEM 15500' AND UNCTLED WITHIN 20 MI OF THE FIFTH BUSIEST ARPT IS ASKING FOR A MIDAIR. THE AIRSPACE IS MUCH TOO UNRESTRICTED.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.