Narrative:

We had just leveled at FL330 with ZHU and were given a left turn direct to szw. I advised the first officer who was the PF that I would be off the radio momentarily to make a PA. Approximately 5 seconds after I had turned off my speaker switch to make the PA, we got a threat advisory. I immediately went to the 5 mi scale on TCASII and observed a target at my altitude at approximately 4 mi going from my right to left. At the same time, the autoplt was disconnected and we descended to FL310 as per the ATC controller's frantic instructions which I did not hear due to the speaker switch being momentarily off. We did not receive an RA. I asked the houston controller immediately what had happened and the controller advised that separation had been compromised down to 4 mi. No further explanation as to how we got into this situation was offered by the controller. The controller had given us the left turn direct to szw after I had requested direct downline somewhere due to us running behind schedule. Controller was trying to help us out.

Related reports:

Google
 

Original NASA ASRS Text

Title: TFC SEPARATION LOST WHEN A DIRECT VECTOR IS GIVEN AT AN ACR'S REQUEST AT CRUISE ALT.

Narrative: WE HAD JUST LEVELED AT FL330 WITH ZHU AND WERE GIVEN A L TURN DIRECT TO SZW. I ADVISED THE FO WHO WAS THE PF THAT I WOULD BE OFF THE RADIO MOMENTARILY TO MAKE A PA. APPROX 5 SECONDS AFTER I HAD TURNED OFF MY SPEAKER SWITCH TO MAKE THE PA, WE GOT A THREAT ADVISORY. I IMMEDIATELY WENT TO THE 5 MI SCALE ON TCASII AND OBSERVED A TARGET AT MY ALT AT APPROX 4 MI GOING FROM MY R TO L. AT THE SAME TIME, THE AUTOPLT WAS DISCONNECTED AND WE DSNDED TO FL310 AS PER THE ATC CTLR'S FRANTIC INSTRUCTIONS WHICH I DID NOT HEAR DUE TO THE SPEAKER SWITCH BEING MOMENTARILY OFF. WE DID NOT RECEIVE AN RA. I ASKED THE HOUSTON CTLR IMMEDIATELY WHAT HAD HAPPENED AND THE CTLR ADVISED THAT SEPARATION HAD BEEN COMPROMISED DOWN TO 4 MI. NO FURTHER EXPLANATION AS TO HOW WE GOT INTO THIS SIT WAS OFFERED BY THE CTLR. THE CTLR HAD GIVEN US THE L TURN DIRECT TO SZW AFTER I HAD REQUESTED DIRECT DOWNLINE SOMEWHERE DUE TO US RUNNING BEHIND SCHEDULE. CTLR WAS TRYING TO HELP US OUT.

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.