TCASII is credited with preventing an near midair collision caused by a TRACON approach controller e...

Attributes
ACN	281649
Time
Date	199408
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : arm airport : iad
State Reference	VA
Altitude	msl bound lower : 8000 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : iad
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent other
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Flight Phase	cruise other
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer pilot : cfi
Experience	flight time last 90 days : 200 flight time total : 8000 flight time type : 200
ASRS Report	281649
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 220 flight time total : 13000 flight time type : 8000
ASRS Report	281898
Events
Anomaly	conflict : nmac non adherence : required legal separation other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

While descending for approach into iad we were cleared to 7000 ft. At 9000 ft we were issued a TA from our TCASII and began our search for the traffic approximately 1000 ft below our altitude. The TA changed to an RA and commanded a level off. The captain (PF) began the level off and simultaneously spotted the traffic at 10 O'clock low. We leveled at 8500 ft and asked approach if they had 10 O'clock traffic for us at 8000 ft. The controller acknowledged the traffic and assigned us 8000 ft. We stayed at 8500 ft until the traffic passed under us and were soon reclred to 7000 ft. The rest of the arrival went smoothly. The controller apologized for the error and gave us a phone number to call. TCASII worked fine in this case. Without it this could have been a very close call if not an accident.

Original NASA ASRS Text

Title: TCASII IS CREDITED WITH PREVENTING AN NMAC CAUSED BY A TRACON APCH CTLR ERROR.

Narrative: WHILE DSNDING FOR APCH INTO IAD WE WERE CLRED TO 7000 FT. AT 9000 FT WE WERE ISSUED A TA FROM OUR TCASII AND BEGAN OUR SEARCH FOR THE TFC APPROX 1000 FT BELOW OUR ALT. THE TA CHANGED TO AN RA AND COMMANDED A LEVEL OFF. THE CAPT (PF) BEGAN THE LEVEL OFF AND SIMULTANEOUSLY SPOTTED THE TFC AT 10 O'CLOCK LOW. WE LEVELED AT 8500 FT AND ASKED APCH IF THEY HAD 10 O'CLOCK TFC FOR US AT 8000 FT. THE CTLR ACKNOWLEDGED THE TFC AND ASSIGNED US 8000 FT. WE STAYED AT 8500 FT UNTIL THE TFC PASSED UNDER US AND WERE SOON RECLRED TO 7000 FT. THE REST OF THE ARR WENT SMOOTHLY. THE CTLR APOLOGIZED FOR THE ERROR AND GAVE US A PHONE NUMBER TO CALL. TCASII WORKED FINE IN THIS CASE. WITHOUT IT THIS COULD HAVE BEEN A VERY CLOSE CALL IF NOT AN ACCIDENT.

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.

TCASII is credited with preventing an near midair collision caused by a TRACON approach controller error.