Cga descended below assigned altitude and conflicted with an eastbound small transport.

Attributes
ACN	123088
Time
Date	198909
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : lse
State Reference	WI
Altitude	msl bound lower : 15800 msl bound upper : 17000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau tower : hsv
Operator	general aviation : corporate
Make Model Name	Small Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Aircraft 2
Operator	general aviation : corporate
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 70 flight time total : 10000 flight time type : 1000
ASRS Report	123088
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 60 flight time total : 4500 flight time type : 200
ASRS Report	123093
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : clearance non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	faa : investigated
Miss Distance	horizontal : 20000 vertical : 200
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

The controller cleared us to descend to 15,000' which I read back and set in the altitude alerter. At about 16,500' she advised us to level off at 17,000'. We reported we were approached 16,000' and we started back to 17,000' and asked the controller if that is where we should be. She stated that she wanted us at 17,000'. We spotted an aircraft at about 1 O'clock below us at about 3-4 mi. We did not have to turn or make any abrupt pitch changes to avoid the other traffic. We were given many altitude adjustments during the entire descent and all were read back to the controller. We did approach 16,000' before we started back to 17,000'. The traffic appeared to be below us at all times. Callback conversation with reporter revealed the following: the copilot reporter stated that an altitude deviation was filed against them by the FAA. A tape of the incident was received through an foia request, and it revealed that the controller issued the correct altitude (17,000'), but the pilot reporter had copied the wrong altitude and the wrong altimeter setting. His readback to the controller of the altitude was garbled on the tape and the controller never received it. The other traffic was an small transport on an easterly heading at about 16,000'. The lowest altitude they got was 15,800', the other aircraft passed about 4 mi off their right side above them.

Original NASA ASRS Text

Title: CGA DESCENDED BELOW ASSIGNED ALT AND CONFLICTED WITH AN EASTBOUND SMT.

Narrative: THE CTLR CLRED US TO DSND TO 15,000' WHICH I READ BACK AND SET IN THE ALT ALERTER. AT ABOUT 16,500' SHE ADVISED US TO LEVEL OFF AT 17,000'. WE REPORTED WE WERE APCHED 16,000' AND WE STARTED BACK TO 17,000' AND ASKED THE CTLR IF THAT IS WHERE WE SHOULD BE. SHE STATED THAT SHE WANTED US AT 17,000'. WE SPOTTED AN ACFT AT ABOUT 1 O'CLOCK BELOW US AT ABOUT 3-4 MI. WE DID NOT HAVE TO TURN OR MAKE ANY ABRUPT PITCH CHANGES TO AVOID THE OTHER TFC. WE WERE GIVEN MANY ALT ADJUSTMENTS DURING THE ENTIRE DSCNT AND ALL WERE READ BACK TO THE CTLR. WE DID APCH 16,000' BEFORE WE STARTED BACK TO 17,000'. THE TFC APPEARED TO BE BELOW US AT ALL TIMES. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: THE COPLT REPORTER STATED THAT AN ALT DEVIATION WAS FILED AGAINST THEM BY THE FAA. A TAPE OF THE INCIDENT WAS RECEIVED THROUGH AN FOIA REQUEST, AND IT REVEALED THAT THE CTLR ISSUED THE CORRECT ALT (17,000'), BUT THE PLT REPORTER HAD COPIED THE WRONG ALT AND THE WRONG ALTIMETER SETTING. HIS READBACK TO THE CTLR OF THE ALT WAS GARBLED ON THE TAPE AND THE CTLR NEVER RECEIVED IT. THE OTHER TFC WAS AN SMT ON AN EASTERLY HDG AT ABOUT 16,000'. THE LOWEST ALT THEY GOT WAS 15,800', THE OTHER ACFT PASSED ABOUT 4 MI OFF THEIR RIGHT SIDE ABOVE THEM.

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.