Narrative:

While on williamsport 1 arrival inbound to ewr and being controled by ZNY, received clearance to FL190 by the hayed intersection. Approaching FL190 (approximately 10 mi from hayed) received clearance to first slow to 250 KTS then continue descent. Captain and first officer (flying) heard descent limit to be 10000 ft (frequency very busy) and captain read back clearance of 10000 ft to ATC. First officer set 10000 ft in altitude alert window, and verbalized new altitude. After captain's readback, no further acknowledgement/correction was received from ATC. The so was not monitoring radio xmissions at this time due to difficulty receiving ATIS information at ewr. Crew deemed timing of ATIS information important, so appropriate brief at unfamiliar airport could commence. At approximately 13000 ft, ATC called out traffic at our 12 O'clock position. Almost simultaneously crew verified traffic on TCASII (advisory) and visually sighted small aircraft. Descent was shallowed, and leveloff commenced at 12500 ft. Our aircraft leveled off at 12200 ft. Passing 12500 ft, ATC asked 'what altitude are you at?' we did not immediately respond because of reacting to sighted aircraft. Our closest proximity to sighted aircraft was never less than 2.5 mi. ATC stated we should be at 13000 ft. While climbing back (800 ft) to 13000 ft, captain transmitted that 10000 ft had been read back during earlier transmission and that 10000 ft was what was set in the altitude alert window. ATC stated that the alarm had triggered, and that the tapes would be pulled. After arriving at ewr, captain phoned ZNY supervisor. The supervisor verified that the tapes revealed that the controller cleared us to 13000 ft, but our readback had been 10000 ft. The controller had failed to acknowledge/correct our readback transmission. The supervisor stated, 'it was our (ATC) fault.' contributing factors: extremely busy frequency with like-sounding call sign to our own. Suspect 10000 ft call may have been transmitted to other aircraft. Could not receive ATIS inside of 50 mi at ewr, causing so to be out of the ATC loop. No controller acknowledgement/correction of our altitude readback. Arrival chart expect altitude of 7000 ft at sweet intersection (in front of us) contributed to acceptance of 10000 ft as appropriate altitude. Correction of 250 KT slow down and 10000 ft tended to validate crew's readback. How to prevent recurrence: ATC acknowledgement/corrections to all aircraft altitude readbacks, especially in busy radio transmission environment. ACARS on all aircraft to receive ATIS information in order to keep so in loop during critical phases of flight.

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Original NASA ASRS Text

Title: B727 FLC DSNDED THROUGH CLRED ALT APCHING EWR.

Narrative: WHILE ON WILLIAMSPORT 1 ARR INBOUND TO EWR AND BEING CTLED BY ZNY, RECEIVED CLRNC TO FL190 BY THE HAYED INTXN. APCHING FL190 (APPROX 10 MI FROM HAYED) RECEIVED CLRNC TO FIRST SLOW TO 250 KTS THEN CONTINUE DSCNT. CAPT AND FO (FLYING) HEARD DSCNT LIMIT TO BE 10000 FT (FREQ VERY BUSY) AND CAPT READ BACK CLRNC OF 10000 FT TO ATC. FO SET 10000 FT IN ALT ALERT WINDOW, AND VERBALIZED NEW ALT. AFTER CAPT'S READBACK, NO FURTHER ACKNOWLEDGEMENT/CORRECTION WAS RECEIVED FROM ATC. THE SO WAS NOT MONITORING RADIO XMISSIONS AT THIS TIME DUE TO DIFFICULTY RECEIVING ATIS INFO AT EWR. CREW DEEMED TIMING OF ATIS INFO IMPORTANT, SO APPROPRIATE BRIEF AT UNFAMILIAR ARPT COULD COMMENCE. AT APPROX 13000 FT, ATC CALLED OUT TFC AT OUR 12 O'CLOCK POS. ALMOST SIMULTANEOUSLY CREW VERIFIED TFC ON TCASII (ADVISORY) AND VISUALLY SIGHTED SMALL ACFT. DSCNT WAS SHALLOWED, AND LEVELOFF COMMENCED AT 12500 FT. OUR ACFT LEVELED OFF AT 12200 FT. PASSING 12500 FT, ATC ASKED 'WHAT ALT ARE YOU AT?' WE DID NOT IMMEDIATELY RESPOND BECAUSE OF REACTING TO SIGHTED ACFT. OUR CLOSEST PROX TO SIGHTED ACFT WAS NEVER LESS THAN 2.5 MI. ATC STATED WE SHOULD BE AT 13000 FT. WHILE CLBING BACK (800 FT) TO 13000 FT, CAPT XMITTED THAT 10000 FT HAD BEEN READ BACK DURING EARLIER XMISSION AND THAT 10000 FT WAS WHAT WAS SET IN THE ALT ALERT WINDOW. ATC STATED THAT THE ALARM HAD TRIGGERED, AND THAT THE TAPES WOULD BE PULLED. AFTER ARRIVING AT EWR, CAPT PHONED ZNY SUPVR. THE SUPVR VERIFIED THAT THE TAPES REVEALED THAT THE CTLR CLRED US TO 13000 FT, BUT OUR READBACK HAD BEEN 10000 FT. THE CTLR HAD FAILED TO ACKNOWLEDGE/CORRECT OUR READBACK XMISSION. THE SUPVR STATED, 'IT WAS OUR (ATC) FAULT.' CONTRIBUTING FACTORS: EXTREMELY BUSY FREQ WITH LIKE-SOUNDING CALL SIGN TO OUR OWN. SUSPECT 10000 FT CALL MAY HAVE BEEN XMITTED TO OTHER ACFT. COULD NOT RECEIVE ATIS INSIDE OF 50 MI AT EWR, CAUSING SO TO BE OUT OF THE ATC LOOP. NO CTLR ACKNOWLEDGEMENT/CORRECTION OF OUR ALT READBACK. ARR CHART EXPECT ALT OF 7000 FT AT SWEET INTXN (IN FRONT OF US) CONTRIBUTED TO ACCEPTANCE OF 10000 FT AS APPROPRIATE ALT. CORRECTION OF 250 KT SLOW DOWN AND 10000 FT TENDED TO VALIDATE CREW'S READBACK. HOW TO PREVENT RECURRENCE: ATC ACKNOWLEDGEMENT/CORRECTIONS TO ALL ACFT ALT READBACKS, ESPECIALLY IN BUSY RADIO XMISSION ENVIRONMENT. ACARS ON ALL ACFT TO RECEIVE ATIS INFO IN ORDER TO KEEP SO IN LOOP DURING CRITICAL PHASES OF FLT.

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.