Air carrier X had less than standard separation with small aircraft in arsa. System error.

Attributes
ACN	170141
Time
Date	199102
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : cos
State Reference	CO
Altitude	msl bound lower : 9200 msl bound upper : 9200
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : cos
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	approach : visual
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 190 flight time total : 7900
ASRS Report	170141
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 1500 vertical : 100
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X had just entered a left downwind for runway 17 at cos after being cleared for visibility approach. As I rolled out on a 350 degree heading the captain took control of the aircraft, exclaiming, 'I've got the airplane.' I looked out the window and saw a white small aircraft Y with blue stripes conducting a steep left hand descending turn trying to get out of our way. The captain had immediately placed air carrier X in a steep left turn to avoid the oncoming traffic. After landing the captain talked to the control tower supervisor and found that small aircraft Y was receiving flight following from approach control and had not been told of our presences in the pattern. We had not been told to look for traffic either. The FAA said we passed each other with 1/4 mi horizontal and 100' vertical sep.

Original NASA ASRS Text

Title: ACR X HAD LESS THAN STANDARD SEPARATION WITH SMA IN ARSA. SYSTEM ERROR.

Narrative: ACR X HAD JUST ENTERED A L DOWNWIND FOR RWY 17 AT COS AFTER BEING CLRED FOR VIS APCH. AS I ROLLED OUT ON A 350 DEG HDG THE CAPT TOOK CTL OF THE ACFT, EXCLAIMING, 'I'VE GOT THE AIRPLANE.' I LOOKED OUT THE WINDOW AND SAW A WHITE SMA Y WITH BLUE STRIPES CONDUCTING A STEEP L HAND DSNDING TURN TRYING TO GET OUT OF OUR WAY. THE CAPT HAD IMMEDIATELY PLACED ACR X IN A STEEP L TURN TO AVOID THE ONCOMING TFC. AFTER LNDG THE CAPT TALKED TO THE CTL TWR SUPVR AND FOUND THAT SMA Y WAS RECEIVING FLT FOLLOWING FROM APCH CTL AND HAD NOT BEEN TOLD OF OUR PRESENCES IN THE PATTERN. WE HAD NOT BEEN TOLD TO LOOK FOR TFC EITHER. THE FAA SAID WE PASSED EACH OTHER WITH 1/4 MI HORIZ AND 100' VERT SEP.

Data retrieved from NASA's ASRS site as of July 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.