Narrative:

Controller was busy giving headings and speed restrictions for spacing. Gave us a heading. There was confusion amongst the crew whether the assigned heading was 170 degree or 270 degree. (Several other aircraft on the arrival were being given 270 degree). Captain attempted several times to verify heading with controller but was blocked and/or unable because of frequency congestion. First officer began turn to 270 degree. Finally controller verified the assigned heading was 170 degree. First officer changed direction of turn. No resulting conflicts are known. Classic example of a controller being overloaded causing a breakdown in communications. Supplemental information from acn 96734. Controller gave a vector of L-170, read back by the captain. First officer understood R-270 and started a right turn to 270. When finally acknowledging our calls, the controller gave us direct buj.

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Original NASA ASRS Text

Title: ACR LGT DEVIATED FROM CLRNC ROUTE.

Narrative: CTLR WAS BUSY GIVING HDGS AND SPD RESTRICTIONS FOR SPACING. GAVE US A HDG. THERE WAS CONFUSION AMONGST THE CREW WHETHER THE ASSIGNED HDG WAS 170 DEG OR 270 DEG. (SEVERAL OTHER ACFT ON THE ARR WERE BEING GIVEN 270 DEG). CAPT ATTEMPTED SEVERAL TIMES TO VERIFY HDG WITH CTLR BUT WAS BLOCKED AND/OR UNABLE BECAUSE OF FREQ CONGESTION. F/O BEGAN TURN TO 270 DEG. FINALLY CTLR VERIFIED THE ASSIGNED HDG WAS 170 DEG. F/O CHANGED DIRECTION OF TURN. NO RESULTING CONFLICTS ARE KNOWN. CLASSIC EXAMPLE OF A CTLR BEING OVERLOADED CAUSING A BREAKDOWN IN COMS. SUPPLEMENTAL INFO FROM ACN 96734. CTLR GAVE A VECTOR OF L-170, READ BACK BY THE CAPT. F/O UNDERSTOOD R-270 AND STARTED A R TURN TO 270. WHEN FINALLY ACKNOWLEDGING OUR CALLS, THE CTLR GAVE US DIRECT BUJ.

Data retrieved from NASA's ASRS site as of August 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.