Flight crew of an MD88 climbed in response to a TCASII RA during descent on a STAR arrival.

Attributes
ACN	368279
Time
Date	199705
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dca
State Reference	DC
Altitude	msl bound lower : 13000 msl bound upper : 13900
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	MD-88
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other arrival star : star enroute airway : dca
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 9000 flight time type : 200
ASRS Report	368279
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 5000 vertical : 450
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

We were level at 13000 ft on irons 3 arrival to dca. ATC (dca approach) called out VFR traffic 500 ft below us, 12 - 1 O'clock, opposite direction. Shortly thereafter, while looking for the traffic, we received an RA for a climb of at least 2000 FPM. We followed the RA until we were visual with the traffic. During the maneuver we deviated 800-900 ft. Problem: why does TCASII activate to resolve a situation where everybody involved was in compliance with regulations?

Original NASA ASRS Text

Title: FLC OF AN MD88 CLBED IN RESPONSE TO A TCASII RA DURING DSCNT ON A STAR ARR.

Narrative: WE WERE LEVEL AT 13000 FT ON IRONS 3 ARR TO DCA. ATC (DCA APCH) CALLED OUT VFR TFC 500 FT BELOW US, 12 - 1 O'CLOCK, OPPOSITE DIRECTION. SHORTLY THEREAFTER, WHILE LOOKING FOR THE TFC, WE RECEIVED AN RA FOR A CLB OF AT LEAST 2000 FPM. WE FOLLOWED THE RA UNTIL WE WERE VISUAL WITH THE TFC. DURING THE MANEUVER WE DEVIATED 800-900 FT. PROB: WHY DOES TCASII ACTIVATE TO RESOLVE A SIT WHERE EVERYBODY INVOLVED WAS IN COMPLIANCE WITH REGS?

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.