Air carrier flight crew heard altitude assignment as 12000 and readback that altitude. Departure con...

Attributes
ACN	87997
Time
Date	198805
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : phl
State Reference	PA
Altitude	msl bound lower : 10000 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny tracon : phl
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time total : 6800
ASRS Report	87997
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time total : 3000
ASRS Report	88454
Events
Anomaly	altitude deviation : overshoot
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Deviation

Narrative:

We had just departed phl airport. The departure controller on initial contact advised us 'after 2000' altitude turn left to 180 degree heading climb and maintain 12000'. We (copilot) read back his clearance verbatim. I dialed in 12000' on the altitude warning device. Climbing through 11000' phl departure called us and advised us he had only given us 10000'. I immediately placed power to idle and descended to 10000'. At which time phl departure advised us to contact new york center. I told my copilot to confirm with new york center what altitude we were to maintain, since phl departure had been too busy to ask a second time to verify 10000' before he switched us to new york center. New york center confirmed 'maintain 10000'.' both my copilot and I heard phl give us 12000' as our initial altitude and 12000' is what we readback to departure control. Departure control did not correct this read back. Upon arriving at our destination, I called phl departure on the telephone. The supervisor was aware of the situation and apologized for the controller not correcting our altitude readback. She said she had not yet listened to the tape but the controller said he initially gave us 10000. A definite communication breakdown occurred because the copilot and I both heard 12000 when 10000 may have been given and the controller not correcting us when we read back 12000. Phl said no conflict had occurred and no violation would be filed. Supplemental information from acn #88454: both the captain and I independently heard a clearance to 12000' as evidenced by our simultaneous actions. I suppose it's possible that we both mistakenly heard the same incorrect altitude assignment. Two things concern me regarding the ATC handling we received. One, that if in fact we had been cleared to 10000' why had I not been corrected by the controller when I acknowledged 12000' and two, why were we not advised of our altitude deviation until we were almost 2000 above what the controller maintained we had been cleared to.

Original NASA ASRS Text

Title: ACR FLT CREW HEARD ALT ASSIGNMENT AS 12000 AND READBACK THAT ALT. DEP CTLR WANTED ACFT TO CLIMB TO 10000, BUT FAILED TO NOTE INCORRECT READBACK OF ALT. OPERATIONAL DEVIATION.

Narrative: WE HAD JUST DEPARTED PHL ARPT. THE DEP CTLR ON INITIAL CONTACT ADVISED US 'AFTER 2000' ALT TURN LEFT TO 180 DEG HEADING CLIMB AND MAINTAIN 12000'. WE (COPLT) READ BACK HIS CLRNC VERBATIM. I DIALED IN 12000' ON THE ALT WARNING DEVICE. CLIMBING THROUGH 11000' PHL DEP CALLED US AND ADVISED US HE HAD ONLY GIVEN US 10000'. I IMMEDIATELY PLACED POWER TO IDLE AND DESCENDED TO 10000'. AT WHICH TIME PHL DEP ADVISED US TO CONTACT NEW YORK CENTER. I TOLD MY COPLT TO CONFIRM WITH NEW YORK CENTER WHAT ALT WE WERE TO MAINTAIN, SINCE PHL DEP HAD BEEN TOO BUSY TO ASK A SECOND TIME TO VERIFY 10000' BEFORE HE SWITCHED US TO NEW YORK CENTER. NEW YORK CENTER CONFIRMED 'MAINTAIN 10000'.' BOTH MY COPLT AND I HEARD PHL GIVE US 12000' AS OUR INITIAL ALT AND 12000' IS WHAT WE READBACK TO DEP CTL. DEP CTL DID NOT CORRECT THIS READ BACK. UPON ARRIVING AT OUR DEST, I CALLED PHL DEP ON THE TELEPHONE. THE SUPERVISOR WAS AWARE OF THE SITUATION AND APOLOGIZED FOR THE CTLR NOT CORRECTING OUR ALT READBACK. SHE SAID SHE HAD NOT YET LISTENED TO THE TAPE BUT THE CTLR SAID HE INITIALLY GAVE US 10000. A DEFINITE COMMUNICATION BREAKDOWN OCCURRED BECAUSE THE COPLT AND I BOTH HEARD 12000 WHEN 10000 MAY HAVE BEEN GIVEN AND THE CTLR NOT CORRECTING US WHEN WE READ BACK 12000. PHL SAID NO CONFLICT HAD OCCURRED AND NO VIOLATION WOULD BE FILED. SUPPLEMENTAL INFORMATION FROM ACN #88454: BOTH THE CAPT AND I INDEPENDENTLY HEARD A CLRNC TO 12000' AS EVIDENCED BY OUR SIMULTANEOUS ACTIONS. I SUPPOSE IT'S POSSIBLE THAT WE BOTH MISTAKENLY HEARD THE SAME INCORRECT ALT ASSIGNMENT. TWO THINGS CONCERN ME REGARDING THE ATC HANDLING WE RECEIVED. ONE, THAT IF IN FACT WE HAD BEEN CLRED TO 10000' WHY HAD I NOT BEEN CORRECTED BY THE CTLR WHEN I ACKNOWLEDGED 12000' AND TWO, WHY WERE WE NOT ADVISED OF OUR ALT DEVIATION UNTIL WE WERE ALMOST 2000 ABOVE WHAT THE CTLR MAINTAINED WE HAD BEEN CLRED TO.

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.

Air carrier flight crew heard altitude assignment as 12000 and readback that altitude. Departure controller wanted aircraft to climb to 10000, but failed to note incorrect readback of altitude. Operational deviation.