Narrative:

Approximately 45 mi west of delancey VOR, descending, boston ARTCC issued the flight a further descent clearance. The controller's transmission was partly broken. I had received 'large transport X cross-??- at 11000'.' the captain was making a PA announcement. I requested the controller to repeat the crossing point stating that I had heard the altitude of 11000'. The controller stated: 'large transport X cross five mi southeast of delancey at one one thousand.' I read back the clearance: 'cross five mi southeast of delancey at 11000', large transport X.' the controller made a couple xmissions to other flts. The controller then requested a verification of our readback. I then repeated the clearance as before: 'cross five mi southeast of delancey at 11000', large transport X.' the captain finished his PA announcement and I advised him of the clearance. About six mi west of delancey descending through 12000', I heard another clearance from the controller; 'large transport X ten mi out at one zero thousand.' the captain read back the clearance: 'delancey, cross ten out at 10000', large transport X.' believing the flight was now cleared to 10000' 10 mi southeast of delancey, I continued descending to comply with the revised clearance. Overhead delancey in a turn down the arwy toward flips intersection the controller requested our altitude. The captain again requested our cleared altitude. The response after a few seconds was: 'I think you were involved in an altitude deviation.' the captain obtained a phone number to contact boston ARTCC. The flight was then handed over to new york approach and landed at the destination. The captain briefed me on the ensuing conversation with boston ARTCC. Evidently the revised clearance had not been a clearance but a traffic advisory. My conclusion is the traffic advisory was misunderstood as a revised crossing clearance with the clearance readback as being accepted as a traffic advisory acknowledgement. In closing I must say the revised clearance and readback would fit in with standard, everyday operations, whereas I cannot recall ever using or hearing another pilot acknowledge a traffic advisory by stating said traffic's position. A more standard acknowledgement would be: 'traffic not in sight', 'in sight', 'no joy', 'looking', 'keep us advised' etc.

Google
 

Original NASA ASRS Text

Title: FLC TOOK TRAFFIC ADVISORY AS A DESCENT CLRNC WHICH RESULTED IN LESS THAN STANDARD SEPARATION.

Narrative: APPROX 45 MI W OF DELANCEY VOR, DSNDING, BOSTON ARTCC ISSUED THE FLT A FURTHER DSNT CLRNC. THE CTLR'S XMISSION WAS PARTLY BROKEN. I HAD RECEIVED 'LGT X CROSS-??- AT 11000'.' THE CAPT WAS MAKING A PA ANNOUNCEMENT. I REQUESTED THE CTLR TO REPEAT THE XING POINT STATING THAT I HAD HEARD THE ALT OF 11000'. THE CTLR STATED: 'LGT X CROSS FIVE MI SE OF DELANCEY AT ONE ONE THOUSAND.' I READ BACK THE CLRNC: 'CROSS FIVE MI SE OF DELANCEY AT 11000', LGT X.' THE CTLR MADE A COUPLE XMISSIONS TO OTHER FLTS. THE CTLR THEN REQUESTED A VERIFICATION OF OUR READBACK. I THEN REPEATED THE CLRNC AS BEFORE: 'CROSS FIVE MI SE OF DELANCEY AT 11000', LGT X.' THE CAPT FINISHED HIS PA ANNOUNCEMENT AND I ADVISED HIM OF THE CLRNC. ABOUT SIX MI W OF DELANCEY DSNDING THROUGH 12000', I HEARD ANOTHER CLRNC FROM THE CTLR; 'LGT X TEN MI OUT AT ONE ZERO THOUSAND.' THE CAPT READ BACK THE CLRNC: 'DELANCEY, CROSS TEN OUT AT 10000', LGT X.' BELIEVING THE FLT WAS NOW CLRED TO 10000' 10 MI SE OF DELANCEY, I CONTINUED DSNDING TO COMPLY WITH THE REVISED CLRNC. OVERHEAD DELANCEY IN A TURN DOWN THE ARWY TOWARD FLIPS INTXN THE CTLR REQUESTED OUR ALT. THE CAPT AGAIN REQUESTED OUR CLRED ALT. THE RESPONSE AFTER A FEW SECS WAS: 'I THINK YOU WERE INVOLVED IN AN ALT DEV.' THE CAPT OBTAINED A PHONE NUMBER TO CONTACT BOSTON ARTCC. THE FLT WAS THEN HANDED OVER TO NEW YORK APCH AND LANDED AT THE DEST. THE CAPT BRIEFED ME ON THE ENSUING CONVERSATION WITH BOSTON ARTCC. EVIDENTLY THE REVISED CLRNC HAD NOT BEEN A CLRNC BUT A TFC ADVISORY. MY CONCLUSION IS THE TFC ADVISORY WAS MISUNDERSTOOD AS A REVISED XING CLRNC WITH THE CLRNC READBACK AS BEING ACCEPTED AS A TFC ADVISORY ACKNOWLEDGEMENT. IN CLOSING I MUST SAY THE REVISED CLRNC AND READBACK WOULD FIT IN WITH STANDARD, EVERYDAY OPS, WHEREAS I CANNOT RECALL EVER USING OR HEARING ANOTHER PLT ACKNOWLEDGE A TFC ADVISORY BY STATING SAID TFC'S POS. A MORE STANDARD ACKNOWLEDGEMENT WOULD BE: 'TFC NOT IN SIGHT', 'IN SIGHT', 'NO JOY', 'LOOKING', 'KEEP US ADVISED' ETC.

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.