ARTCC controller issues clearance meant for another aircraft with same last 2 number call sign and d...

Attributes
ACN	452318
Time
Date	199910
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : hvq.vor
State Reference	WV
Altitude	msl bound lower : 34000 msl bound upper : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	B777 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	cruise : enroute altitude change cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp pilot : multi engine
Experience	flight time last 90 days : 139 flight time total : 11000 flight time type : 170
ASRS Report	452318
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Gatwick (egkk) international airport for atl. At the time of incident we were on frequency 135.17 (ZOB). I was the PNF, the captain was PF with autoplt engaged. We were level at our cruising altitude of FL350. Center told us to descend to FL330 and to expedite this descent. I acknowledged this clearance and the captain immediately selected vertical speed as the pitch mode on the MCP. The aircraft began a 1500-2000 FPM rate of descent, whereupon the controller then modified the clearance to be level at FL330 in 2 1/2 mins or less. I also read back this clearance. Descending through FL340, the controller asked us to turn to a heading of 220 degrees, which I read back with the additional readback that we were passing FL340 for FL330. The controller then stated that he wanted us to maintain FL350. I read back and confirmed that he wanted us to return to FL350. The captain reversed the descent and we returned to FL350, as previously cleared. I have no idea what caused this incident. There was no reason for us to question the clearance, because of the urgency in the controller's tone of voice for us to expedite this descent. We assumed it was for traffic separation, but in retrospect, it probably was for traffic separation, but for another aircraft. In fact, after our descent and climb back to altitude, we heard what sounded like the same controller issue the same clearance (descend to FL330, be level in 2 1/2 mins or less) to another aircraft. We had a 2 digit call sign and there was another company aircraft on the frequency whose 4 digit call sign was the same as ours. This may have been a factor. Our company is heavily committed to an anti-altitude 'bust' campaign, which I wholeheartedly support. In this incident, the captain and I both confirmed that this clearance was for us, full readbacks were given (to my knowledge), including call sign and our 'double-point' technique was utilized to confirm that the internal communications (cockpit) were correct and set on the MCP and confirmed on the pfd. No TCASII event was triggered in our aircraft.

Original NASA ASRS Text

Title: ARTCC CTLR ISSUES CLRNC MEANT FOR ANOTHER ACFT WITH SAME LAST 2 NUMBER CALL SIGN AND DID NOT CATCH MISTAKE WHEN THE RPTR OF A B777 ACKNOWLEDGED WITH HIS FULL CALL SIGN.

Narrative: GATWICK (EGKK) INTL ARPT FOR ATL. AT THE TIME OF INCIDENT WE WERE ON FREQ 135.17 (ZOB). I WAS THE PNF, THE CAPT WAS PF WITH AUTOPLT ENGAGED. WE WERE LEVEL AT OUR CRUISING ALT OF FL350. CTR TOLD US TO DSND TO FL330 AND TO EXPEDITE THIS DSCNT. I ACKNOWLEDGED THIS CLRNC AND THE CAPT IMMEDIATELY SELECTED VERT SPD AS THE PITCH MODE ON THE MCP. THE ACFT BEGAN A 1500-2000 FPM RATE OF DSCNT, WHEREUPON THE CTLR THEN MODIFIED THE CLRNC TO BE LEVEL AT FL330 IN 2 1/2 MINS OR LESS. I ALSO READ BACK THIS CLRNC. DSNDING THROUGH FL340, THE CTLR ASKED US TO TURN TO A HDG OF 220 DEGS, WHICH I READ BACK WITH THE ADDITIONAL READBACK THAT WE WERE PASSING FL340 FOR FL330. THE CTLR THEN STATED THAT HE WANTED US TO MAINTAIN FL350. I READ BACK AND CONFIRMED THAT HE WANTED US TO RETURN TO FL350. THE CAPT REVERSED THE DSCNT AND WE RETURNED TO FL350, AS PREVIOUSLY CLRED. I HAVE NO IDEA WHAT CAUSED THIS INCIDENT. THERE WAS NO REASON FOR US TO QUESTION THE CLRNC, BECAUSE OF THE URGENCY IN THE CTLR'S TONE OF VOICE FOR US TO EXPEDITE THIS DSCNT. WE ASSUMED IT WAS FOR TFC SEPARATION, BUT IN RETROSPECT, IT PROBABLY WAS FOR TFC SEPARATION, BUT FOR ANOTHER ACFT. IN FACT, AFTER OUR DSCNT AND CLB BACK TO ALT, WE HEARD WHAT SOUNDED LIKE THE SAME CTLR ISSUE THE SAME CLRNC (DSND TO FL330, BE LEVEL IN 2 1/2 MINS OR LESS) TO ANOTHER ACFT. WE HAD A 2 DIGIT CALL SIGN AND THERE WAS ANOTHER COMPANY ACFT ON THE FREQ WHOSE 4 DIGIT CALL SIGN WAS THE SAME AS OURS. THIS MAY HAVE BEEN A FACTOR. OUR COMPANY IS HEAVILY COMMITTED TO AN ANTI-ALT 'BUST' CAMPAIGN, WHICH I WHOLEHEARTEDLY SUPPORT. IN THIS INCIDENT, THE CAPT AND I BOTH CONFIRMED THAT THIS CLRNC WAS FOR US, FULL READBACKS WERE GIVEN (TO MY KNOWLEDGE), INCLUDING CALL SIGN AND OUR 'DOUBLE-POINT' TECHNIQUE WAS UTILIZED TO CONFIRM THAT THE INTERNAL COMS (COCKPIT) WERE CORRECT AND SET ON THE MCP AND CONFIRMED ON THE PFD. NO TCASII EVENT WAS TRIGGERED IN OUR ACFT.

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.

ARTCC controller issues clearance meant for another aircraft with same last 2 number call sign and did not catch mistake when the reporter of a B777 acknowledged with his full call sign.