Small transport flight crew confuses altitude clearance and altimeter setting, altitude deviation.

Attributes
ACN	271855
Time
Date	199405
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : djb
State Reference	OH
Altitude	msl bound lower : 13000 msl bound upper : 17000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Learjet 23
Operating Under FAR Part	Part 91
Flight Phase	descent other
Route In Use	enroute airway : zob
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 250 flight time total : 4800 flight time type : 480
ASRS Report	271855
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Our flight routing was to fly direct dryer (VOR), direct junkr (intersection), and then the junkr arrival into willow run airport (yip). We were told to cross 10 mi south or dryer at flight level 240, which we did. We were then given further clearance to what we believed was 13000 ft, and an altimeter of 30.13. I dialed 13000 ft into the altitude alerter, and a descent, was started. This is where the problem arises. Apparently we were only cleared to 17000 ft. During our descent, we were told that we had falcon traffic off to our right side and lower, and once we cleared that traffic we would be given a lower altitude. I called the falcon traffic in sight as we descended to 13000. We leveled off at 13000 and proceeded to junkr. The controller then asked us our assigned altitude, and I replied back to him 13000. (At that time he never said anything about us being at the wrong assigned altitude, or that we ever had an altitude conflict with another aircraft.) . He then gave us further clearance to 10000 ft, and we complied with that clearance. It wasn't until a controller later in our flight informed us to call ZOB when we got on the ground, that we were even aware there may have been a problem. Human considerations: crew: I believe the problem occurred when I read back the assigned altitude. I confused the altitude with the altimeter reading. The altimeter readback was 30.13 and I then dialed in 13000 in the altitude alerter, instead of 17000. Both myself and my first officer both agreed and believed 13000 was our altitude. Controller: when I had descended through my altitude, I would have liked the controller to bring it to my attention, in the interest of safety for my crew and other aircraft.

Original NASA ASRS Text

Title: SMT FLC CONFUSES ALT CLRNC AND ALTIMETER SETTING, ALTDEV.

Narrative: OUR FLT RTING WAS TO FLY DIRECT DRYER (VOR), DIRECT JUNKR (INTXN), AND THEN THE JUNKR ARR INTO WILLOW RUN ARPT (YIP). WE WERE TOLD TO CROSS 10 MI S OR DRYER AT FLT LEVEL 240, WHICH WE DID. WE WERE THEN GIVEN FURTHER CLRNC TO WHAT WE BELIEVED WAS 13000 FT, AND AN ALTIMETER OF 30.13. I DIALED 13000 FT INTO THE ALT ALERTER, AND A DSCNT, WAS STARTED. THIS IS WHERE THE PROB ARISES. APPARENTLY WE WERE ONLY CLRED TO 17000 FT. DURING OUR DSCNT, WE WERE TOLD THAT WE HAD FALCON TFC OFF TO OUR R SIDE AND LOWER, AND ONCE WE CLRED THAT TFC WE WOULD BE GIVEN A LOWER ALT. I CALLED THE FALCON TFC IN SIGHT AS WE DSNDED TO 13000. WE LEVELED OFF AT 13000 AND PROCEEDED TO JUNKR. THE CTLR THEN ASKED US OUR ASSIGNED ALT, AND I REPLIED BACK TO HIM 13000. (AT THAT TIME HE NEVER SAID ANYTHING ABOUT US BEING AT THE WRONG ASSIGNED ALT, OR THAT WE EVER HAD AN ALT CONFLICT WITH ANOTHER ACFT.) . HE THEN GAVE US FURTHER CLRNC TO 10000 FT, AND WE COMPLIED WITH THAT CLRNC. IT WASN'T UNTIL A CTLR LATER IN OUR FLT INFORMED US TO CALL ZOB WHEN WE GOT ON THE GND, THAT WE WERE EVEN AWARE THERE MAY HAVE BEEN A PROB. HUMAN CONSIDERATIONS: CREW: I BELIEVE THE PROB OCCURRED WHEN I READ BACK THE ASSIGNED ALT. I CONFUSED THE ALT WITH THE ALTIMETER READING. THE ALTIMETER READBACK WAS 30.13 AND I THEN DIALED IN 13000 IN THE ALT ALERTER, INSTEAD OF 17000. BOTH MYSELF AND MY FO BOTH AGREED AND BELIEVED 13000 WAS OUR ALT. CTLR: WHEN I HAD DSNDED THROUGH MY ALT, I WOULD HAVE LIKED THE CTLR TO BRING IT TO MY ATTN, IN THE INTEREST OF SAFETY FOR MY CREW AND OTHER 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.