Narrative:

The incident described took place on a scheduled airline flight from phl to clt in daylight VMC. The flight was conducted in an air carrier advanced technology medium large transport with approximately 100 passengers. As our flight approached mxe the phl departure handed us over to the ny center. My first officer was working the communication radio. On initial contact with the center we were cleared along the revised routing that I had anticipated and were further instructed to turn to a 265 degree heading to join the new route and to maintain 10000 ft and 250 KTS. At this point in time I was manually flying the aircraft although I did have the autothrottles turned on. The revised clearance was received by us as we were leaving approximately 8500 ft about 4 mi southeast of mxe. As the first officer acknowledged the clearance I initiated the turn to the desired heading and executed the new routing. This was more involved than just pushing the execute button, although that was the necessary first step. After execution, I proceeded to do a direct intercept to the first point on our new route that was passed mxe. As I accomplished this I looked up to check our altitude and we were rapidly approaching 10000 ft. The autothrottles had not started reducing thrust as I was expecting in order to maintain the desired 250 KTS and 10000 ft altitude. A moment of confusion resulted in my mind as I tried to sort out what was happening. I started easing over the nose to level off and clicked off the autothrottles as I began pulling back the power. At this point our speed had risen to about 280 KTS and our altitude was about 10200 ft. I glanced over to the altitude alerter and saw that 25000 ft was set. This setting was not verified by me when it was set as is required by our company's altitude awareness program. This was the third day of a 3 day trip and we had been fairly consistent in applying the altitude awareness procedures. I asked the first officer if the setting was indeed correct for I had missed the call that had assigned us that altitude. She asserted that 25000 ft was indeed our assigned altitude. I was not entirely convinced, but on the strength of her conviction and in order to prevent placing unusual G forces on the passengers I allowed the plane to continue a slight climb and ask the first officer to verify with center our assigned altitude. Center confirmed that 10000 ft was our clearance altitude. The first officer stated to the center that she had readback 25000 ft. As this conversation was continuing I pulled the throttles to idle and gradually descended back to 10000 ft. We had reached 10500 ft. Shortly after we were given normal speed and further climb to 35000 ft. As the ny controller handed us off he advised us that we were involved in a pilot deviation and he read us a phone number to call once we got on the ground. Needless to say both myself and the first officer were disturbed by these events. We discussed what had occurred as we proceeded. My first officer said that she was anticipating a higher altitude as we reached 10000 ft which is a common occurrence in the ATC system. Upon hearing the 250 KTS speed restriction she interpreted this as the new assigned altitude of FL250. As I questioned her about the altitude she stated that she had read back 250 to the controller who failed to object. Upon arriving charlotte we called the center number and a conversation with a section supervisor ensued. He had pulled the tapes and had listened to the exchange between the flight and controller. It was determined from the tape that we had not been assigned FL250 but 250 KTS. The first officer had indeed read back 2-5-0 but she left off the flight level prefix and the knots suffix. The controller just assumed that she was acknowledging the speed restriction. I have no recollection of the first officer's readback, but I was quite certain of the controller's clearance and was hence caught off guard wht the autothrottles failed to respond as I anticipated. If the alerter had been set to 10000 ft the autothrottles would have pulled the thrust back in order to maintain the desired altitude and speed. Note: I was operating in the level change mode instead of the VNAV mode because of the 250 KT restriction. It there is any question in either crew member's mind about a clearance, do not hesitate to ask for verification. Use standard comphraseology in all your radio communications. The crew system works: although the wrong altitude was set, the other crew member questioned the setting (albeit late) and no harm was done to life or property. The crew caught the deviation before ATC who may have never caught it west/O the call for verification attracting attention to our flight. Neither manual or automatic flight control is more safe in any given situation. In this particular instance if I had been using the autoplt, the degree of deviation would probably have been greater, on the other hand, by having the autothrottles hooked up while manually flying possibly prevented a larger deviation because the failure of the automatic system to perform as expected allowed quicker pilot intervention since my hands were already on the controls. Supplemental information from acn 178392. We were told that there was a possibility of a pilot deviation, whereas investigation revealed, according to the ARTCC supervisor, that sep requirements had not been compromised and that there would be no enforcement action from ny center.

Google
 

Original NASA ASRS Text

Title: ADVTECH ACR MLG EXPERIENCES ALT OVERSHOOT IN CLIMB.

Narrative: THE INCIDENT DESCRIBED TOOK PLACE ON A SCHEDULED AIRLINE FLT FROM PHL TO CLT IN DAYLIGHT VMC. THE FLT WAS CONDUCTED IN AN ACR ADVANCED TECHNOLOGY MLG WITH APPROX 100 PAXS. AS OUR FLT APCHED MXE THE PHL DEP HANDED US OVER TO THE NY CTR. MY FO WAS WORKING THE COM RADIO. ON INITIAL CONTACT WITH THE CTR WE WERE CLRED ALONG THE REVISED RTING THAT I HAD ANTICIPATED AND WERE FURTHER INSTRUCTED TO TURN TO A 265 DEG HDG TO JOIN THE NEW RTE AND TO MAINTAIN 10000 FT AND 250 KTS. AT THIS POINT IN TIME I WAS MANUALLY FLYING THE ACFT ALTHOUGH I DID HAVE THE AUTOTHROTTLES TURNED ON. THE REVISED CLRNC WAS RECEIVED BY US AS WE WERE LEAVING APPROX 8500 FT ABOUT 4 MI SE OF MXE. AS THE FO ACKNOWLEDGED THE CLRNC I INITIATED THE TURN TO THE DESIRED HDG AND EXECUTED THE NEW RTING. THIS WAS MORE INVOLVED THAN JUST PUSHING THE EXECUTE BUTTON, ALTHOUGH THAT WAS THE NECESSARY FIRST STEP. AFTER EXECUTION, I PROCEEDED TO DO A DIRECT INTERCEPT TO THE FIRST POINT ON OUR NEW RTE THAT WAS PASSED MXE. AS I ACCOMPLISHED THIS I LOOKED UP TO CHK OUR ALT AND WE WERE RAPIDLY APCHING 10000 FT. THE AUTOTHROTTLES HAD NOT STARTED REDUCING THRUST AS I WAS EXPECTING IN ORDER TO MAINTAIN THE DESIRED 250 KTS AND 10000 FT ALT. A MOMENT OF CONFUSION RESULTED IN MY MIND AS I TRIED TO SORT OUT WHAT WAS HAPPENING. I STARTED EASING OVER THE NOSE TO LEVEL OFF AND CLICKED OFF THE AUTOTHROTTLES AS I BEGAN PULLING BACK THE PWR. AT THIS POINT OUR SPD HAD RISEN TO ABOUT 280 KTS AND OUR ALT WAS ABOUT 10200 FT. I GLANCED OVER TO THE ALT ALERTER AND SAW THAT 25000 FT WAS SET. THIS SETTING WAS NOT VERIFIED BY ME WHEN IT WAS SET AS IS REQUIRED BY OUR COMPANY'S ALT AWARENESS PROGRAM. THIS WAS THE THIRD DAY OF A 3 DAY TRIP AND WE HAD BEEN FAIRLY CONSISTENT IN APPLYING THE ALT AWARENESS PROCS. I ASKED THE FO IF THE SETTING WAS INDEED CORRECT FOR I HAD MISSED THE CALL THAT HAD ASSIGNED US THAT ALT. SHE ASSERTED THAT 25000 FT WAS INDEED OUR ASSIGNED ALT. I WAS NOT ENTIRELY CONVINCED, BUT ON THE STRENGTH OF HER CONVICTION AND IN ORDER TO PREVENT PLACING UNUSUAL G FORCES ON THE PAXS I ALLOWED THE PLANE TO CONTINUE A SLIGHT CLB AND ASK THE FO TO VERIFY WITH CTR OUR ASSIGNED ALT. CTR CONFIRMED THAT 10000 FT WAS OUR CLRNC ALT. THE FO STATED TO THE CTR THAT SHE HAD READBACK 25000 FT. AS THIS CONVERSATION WAS CONTINUING I PULLED THE THROTTLES TO IDLE AND GRADUALLY DSNDED BACK TO 10000 FT. WE HAD REACHED 10500 FT. SHORTLY AFTER WE WERE GIVEN NORMAL SPD AND FURTHER CLB TO 35000 FT. AS THE NY CTLR HANDED US OFF HE ADVISED US THAT WE WERE INVOLVED IN A PLT DEV AND HE READ US A PHONE NUMBER TO CALL ONCE WE GOT ON THE GND. NEEDLESS TO SAY BOTH MYSELF AND THE FO WERE DISTURBED BY THESE EVENTS. WE DISCUSSED WHAT HAD OCCURRED AS WE PROCEEDED. MY FO SAID THAT SHE WAS ANTICIPATING A HIGHER ALT AS WE REACHED 10000 FT WHICH IS A COMMON OCCURRENCE IN THE ATC SYS. UPON HEARING THE 250 KTS SPD RESTRICTION SHE INTERPRETED THIS AS THE NEW ASSIGNED ALT OF FL250. AS I QUESTIONED HER ABOUT THE ALT SHE STATED THAT SHE HAD READ BACK 250 TO THE CTLR WHO FAILED TO OBJECT. UPON ARRIVING CHARLOTTE WE CALLED THE CTR NUMBER AND A CONVERSATION WITH A SECTION SUPVR ENSUED. HE HAD PULLED THE TAPES AND HAD LISTENED TO THE EXCHANGE BTWN THE FLT AND CTLR. IT WAS DETERMINED FROM THE TAPE THAT WE HAD NOT BEEN ASSIGNED FL250 BUT 250 KTS. THE FO HAD INDEED READ BACK 2-5-0 BUT SHE LEFT OFF THE FLT LEVEL PREFIX AND THE KNOTS SUFFIX. THE CTLR JUST ASSUMED THAT SHE WAS ACKNOWLEDGING THE SPD RESTRICTION. I HAVE NO RECOLLECTION OF THE FO'S READBACK, BUT I WAS QUITE CERTAIN OF THE CTLR'S CLRNC AND WAS HENCE CAUGHT OFF GUARD WHT THE AUTOTHROTTLES FAILED TO RESPOND AS I ANTICIPATED. IF THE ALERTER HAD BEEN SET TO 10000 FT THE AUTOTHROTTLES WOULD HAVE PULLED THE THRUST BACK IN ORDER TO MAINTAIN THE DESIRED ALT AND SPD. NOTE: I WAS OPERATING IN THE LEVEL CHANGE MODE INSTEAD OF THE VNAV MODE BECAUSE OF THE 250 KT RESTRICTION. IT THERE IS ANY QUESTION IN EITHER CREW MEMBER'S MIND ABOUT A CLRNC, DO NOT HESITATE TO ASK FOR VERIFICATION. USE STANDARD COMPHRASEOLOGY IN ALL YOUR RADIO COMS. THE CREW SYS WORKS: ALTHOUGH THE WRONG ALT WAS SET, THE OTHER CREW MEMBER QUESTIONED THE SETTING (ALBEIT LATE) AND NO HARM WAS DONE TO LIFE OR PROPERTY. THE CREW CAUGHT THE DEV BEFORE ATC WHO MAY HAVE NEVER CAUGHT IT W/O THE CALL FOR VERIFICATION ATTRACTING ATTN TO OUR FLT. NEITHER MANUAL OR AUTO FLT CTL IS MORE SAFE IN ANY GIVEN SITUATION. IN THIS PARTICULAR INSTANCE IF I HAD BEEN USING THE AUTOPLT, THE DEG OF DEV WOULD PROBABLY HAVE BEEN GREATER, ON THE OTHER HAND, BY HAVING THE AUTOTHROTTLES HOOKED UP WHILE MANUALLY FLYING POSSIBLY PREVENTED A LARGER DEV BECAUSE THE FAILURE OF THE AUTO SYS TO PERFORM AS EXPECTED ALLOWED QUICKER PLT INTERVENTION SINCE MY HANDS WERE ALREADY ON THE CTLS. SUPPLEMENTAL INFO FROM ACN 178392. WE WERE TOLD THAT THERE WAS A POSSIBILITY OF A PLT DEV, WHEREAS INVESTIGATION REVEALED, ACCORDING TO THE ARTCC SUPVR, THAT SEP REQUIREMENTS HAD NOT BEEN COMPROMISED AND THAT THERE WOULD BE NO ENFORCEMENT ACTION FROM NY CTR.

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.