Narrative:

Air carrier X departed dulles on runway 1L, instructed to fly heading 360 degrees, maintain 4000'. Captain was fling. Prior to reaching 4000' we were reclred to 6000'. There was heavy radio traffic and ATC requested a readback twice. We accelerated to 250 KIAS and with a light gross weight we were climbing in excess of 2500 FPM. The WX was VFR with a high overcast, late afternoon and gray day, with snow covered ground. As I called out of 5000' for 6000' we got the altitude alert, and the first officer called traffic and pointed about 10 O'clock, all in a matter of seconds. I immediately acquired the traffic and was shocked that he was so close (estimate about 1 mi). He was near the left post of the captain's forward windshield. The traffic was a small white small aircraft Y aircraft. He was in a left turn, and in our climbing attitude. I could not determine if he was climbing or level. His turn may have been an evasive maneuver, but it was taking him into our flight path. I immediately started a right turn of about 30 degree bank and realized he was still closing, so I increased the bank to approximately 45 degrees. The aircraft passed to our left (approximately 1/2-1/4 mi) and about 100' below us. We reported to ATC. The first officer told me we had been reclred to 5000' as we were in the evasive maneuver. ATC then told us we could maintain 5000' on heading 040 degrees. I commend the first officer for maintaining a traffic watch as we had briefed. I feel the aircraft being white against a white background was a definite factor. I also question an altitude change by ATC in such proximity of traffic west/O an urgent traffic alert. It could have been distracting. I also feel that TCAS could have been very helpful in this case. On debriefing the first officer recalled we had acquired the traffic at 5300' and passed him at about 5700' our heading of 030 degrees. Post discussion with ATC, they question why we had not maintained 5000' as we had been instructed. I did not hear the clearance to maintain 5000' and the first officer said we got this clearance during the evasive maneuver approximately 5500' and he had acknowledged, but it came too late. I assume I didn't hear the reclrnc because my concentration was on avoiding the traffic.

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Original NASA ASRS Text

Title: ACR X HAD LESS THAN STANDARD SEPARATION FROM SMA Y.

Narrative: ACR X DEPARTED DULLES ON RWY 1L, INSTRUCTED TO FLY HDG 360 DEGS, MAINTAIN 4000'. CAPT WAS FLING. PRIOR TO REACHING 4000' WE WERE RECLRED TO 6000'. THERE WAS HEAVY RADIO TFC AND ATC REQUESTED A READBACK TWICE. WE ACCELERATED TO 250 KIAS AND WITH A LIGHT GROSS WT WE WERE CLBING IN EXCESS OF 2500 FPM. THE WX WAS VFR WITH A HIGH OVCST, LATE AFTERNOON AND GRAY DAY, WITH SNOW COVERED GND. AS I CALLED OUT OF 5000' FOR 6000' WE GOT THE ALT ALERT, AND THE F/O CALLED TFC AND POINTED ABOUT 10 O'CLOCK, ALL IN A MATTER OF SECS. I IMMEDIATELY ACQUIRED THE TFC AND WAS SHOCKED THAT HE WAS SO CLOSE (ESTIMATE ABOUT 1 MI). HE WAS NEAR THE LEFT POST OF THE CAPT'S FORWARD WINDSHIELD. THE TFC WAS A SMALL WHITE SMA Y ACFT. HE WAS IN A LEFT TURN, AND IN OUR CLBING ATTITUDE. I COULD NOT DETERMINE IF HE WAS CLBING OR LEVEL. HIS TURN MAY HAVE BEEN AN EVASIVE MANEUVER, BUT IT WAS TAKING HIM INTO OUR FLT PATH. I IMMEDIATELY STARTED A RIGHT TURN OF ABOUT 30 DEG BANK AND REALIZED HE WAS STILL CLOSING, SO I INCREASED THE BANK TO APPROX 45 DEGS. THE ACFT PASSED TO OUR LEFT (APPROX 1/2-1/4 MI) AND ABOUT 100' BELOW US. WE RPTED TO ATC. THE F/O TOLD ME WE HAD BEEN RECLRED TO 5000' AS WE WERE IN THE EVASIVE MANEUVER. ATC THEN TOLD US WE COULD MAINTAIN 5000' ON HDG 040 DEGS. I COMMEND THE F/O FOR MAINTAINING A TFC WATCH AS WE HAD BRIEFED. I FEEL THE ACFT BEING WHITE AGAINST A WHITE BACKGROUND WAS A DEFINITE FACTOR. I ALSO QUESTION AN ALT CHANGE BY ATC IN SUCH PROX OF TFC W/O AN URGENT TFC ALERT. IT COULD HAVE BEEN DISTRACTING. I ALSO FEEL THAT TCAS COULD HAVE BEEN VERY HELPFUL IN THIS CASE. ON DEBRIEFING THE FO RECALLED WE HAD ACQUIRED THE TFC AT 5300' AND PASSED HIM AT ABOUT 5700' OUR HDG OF 030 DEGS. POST DISCUSSION WITH ATC, THEY QUESTION WHY WE HAD NOT MAINTAINED 5000' AS WE HAD BEEN INSTRUCTED. I DID NOT HEAR THE CLRNC TO MAINTAIN 5000' AND THE F/O SAID WE GOT THIS CLRNC DURING THE EVASIVE MANEUVER APPROX 5500' AND HE HAD ACKNOWLEDGED, BUT IT CAME TOO LATE. I ASSUME I DIDN'T HEAR THE RECLRNC BECAUSE MY CONCENTRATION WAS ON AVOIDING THE TFC.

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.