Near midair collision.

Attributes
ACN	238512
Time
Date	199304
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : bna
State Reference	TN
Altitude	msl bound lower : 6000 msl bound upper : 6500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute airway : bna
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 10000 flight time type : 2000
ASRS Report	238512
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : cfi pilot : atp
Experience	flight time last 90 days : 100 flight time total : 3500 flight time type : 500
ASRS Report	238935
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : nmac non adherence : far non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 0 vertical : 200
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Our aircraft was assigned and maintaining 6000 ft 10 NM east of bna VOR talking to bna approach on 127.17. ATC called VFR traffic at 11 O'clock level at 5500 ft. TCASII gave a 'traffic' aural and 'TA' display with altitude difference decreasing -9, -8, - 7. TCASII then gave us an RA with 'climb' aurals and commanded a vertical climb arc 2000-2500 FPM to which we responded appropriately. When immediate action allowed, we returned our scan to TCASII and both remember seeing a -2 (200 ft) and close to 0 lateral distance as traffic passed directly under us. We had climbed about 500 ft to 6500 ft and advised ATC of the TCASII RA and our altitude deviation. We were given a turn to north and northeast. I feel certain TCASII helped avoid a certain collision and want to emphasize that in this case immediate action in response to the RA was absolutely necessary. Delay would have resulted in collision. TCASII worked!

Original NASA ASRS Text

Title: NMAC.

Narrative: OUR ACFT WAS ASSIGNED AND MAINTAINING 6000 FT 10 NM E OF BNA VOR TALKING TO BNA APCH ON 127.17. ATC CALLED VFR TFC AT 11 O'CLOCK LEVEL AT 5500 FT. TCASII GAVE A 'TFC' AURAL AND 'TA' DISPLAY WITH ALT DIFFERENCE DECREASING -9, -8, - 7. TCASII THEN GAVE US AN RA WITH 'CLB' AURALS AND COMMANDED A VERT CLB ARC 2000-2500 FPM TO WHICH WE RESPONDED APPROPRIATELY. WHEN IMMEDIATE ACTION ALLOWED, WE RETURNED OUR SCAN TO TCASII AND BOTH REMEMBER SEEING A -2 (200 FT) AND CLOSE TO 0 LATERAL DISTANCE AS TFC PASSED DIRECTLY UNDER US. WE HAD CLBED ABOUT 500 FT TO 6500 FT AND ADVISED ATC OF THE TCASII RA AND OUR ALTDEV. WE WERE GIVEN A TURN TO N AND NE. I FEEL CERTAIN TCASII HELPED AVOID A CERTAIN COLLISION AND WANT TO EMPHASIZE THAT IN THIS CASE IMMEDIATE ACTION IN RESPONSE TO THE RA WAS ABSOLUTELY NECESSARY. DELAY WOULD HAVE RESULTED IN COLLISION. TCASII WORKED!

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.