Flight crew of an medium large transport overshot altitude on descent.

Attributes
ACN	296226
Time
Date	199502
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : vuz airport : bhm
State Reference	AL
Altitude	msl bound lower : 11500 msl bound upper : 13000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	enroute airway : ztl
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 12000 flight time type : 240
ASRS Report	296226
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 185 flight time total : 2800 flight time type : 400
ASRS Report	296182
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact other
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 21000 vertical : 700
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While at cruise inbound to bhm, we received clearance to cross 30 mi southeast of bhm at 11000 ft from ZTL. At this time I did my PA, which upon completion the first officer indicated that ZTL wanted us to start down now for 13000 ft. I misinterpreted this to mean we needed to descend through 13000 ft for traffic. Passing through approximately 13000 ft, I visually acquired our traffic and saw it on TCASII, it was at 12000 ft vice the 14000 ft I was expecting. At this point we were in a high rate of descent and I realized I would provide more separation if I expedited down to 11000 ft vice trying to pull up and bottom out at an altitude close to 12000 ft. I called ZTL later and the supervisor said our closest separation was 3.46 mi but that they were filing a pilot error report since the first officer had read back 13000 ft on the tape. The first officer told me that the phraseology used by the controller led him to believe that the initial clearance of 11000 ft at 30 mi still applied, and therefore did not set 13000 ft in the altitude window. To my knowledge neither aircraft took evasive action.

Original NASA ASRS Text

Title: FLC OF AN MLG OVERSHOT ALT ON DSCNT.

Narrative: WHILE AT CRUISE INBOUND TO BHM, WE RECEIVED CLRNC TO CROSS 30 MI SE OF BHM AT 11000 FT FROM ZTL. AT THIS TIME I DID MY PA, WHICH UPON COMPLETION THE FO INDICATED THAT ZTL WANTED US TO START DOWN NOW FOR 13000 FT. I MISINTERPRETED THIS TO MEAN WE NEEDED TO DSND THROUGH 13000 FT FOR TFC. PASSING THROUGH APPROX 13000 FT, I VISUALLY ACQUIRED OUR TFC AND SAW IT ON TCASII, IT WAS AT 12000 FT VICE THE 14000 FT I WAS EXPECTING. AT THIS POINT WE WERE IN A HIGH RATE OF DSCNT AND I REALIZED I WOULD PROVIDE MORE SEPARATION IF I EXPEDITED DOWN TO 11000 FT VICE TRYING TO PULL UP AND BOTTOM OUT AT AN ALT CLOSE TO 12000 FT. I CALLED ZTL LATER AND THE SUPVR SAID OUR CLOSEST SEPARATION WAS 3.46 MI BUT THAT THEY WERE FILING A PLT ERROR RPT SINCE THE FO HAD READ BACK 13000 FT ON THE TAPE. THE FO TOLD ME THAT THE PHRASEOLOGY USED BY THE CTLR LED HIM TO BELIEVE THAT THE INITIAL CLRNC OF 11000 FT AT 30 MI STILL APPLIED, AND THEREFORE DID NOT SET 13000 FT IN THE ALT WINDOW. TO MY KNOWLEDGE NEITHER ACFT TOOK EVASIVE ACTION.

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.