Medium large transport flight crew sets wrong altitude when cleared to descend. Has TCASII RA.

Attributes
ACN	273833
Time
Date	199406
Day	Sat
Place
Locale Reference	atc facility : ont
State Reference	CA
Altitude	msl bound lower : 8000 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ont
Operator	common carrier : air carrier
Make Model Name	MD-80 Super 80
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Starlifter (C141)
Operating Under FAR Part	other : other
Flight Phase	cruise other
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	273833
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : nmac other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were at 10000 ft. We were given a clearance to descend to 9000 ft and a heading of 280 degrees to intercept localizer runway 26L at ontario airport. We misunderstood the clearance and read back cleared to 8000 ft. 8000 ft was set and armed in the FMA. As we intercepted the localizer, we got an RA on traffic to our right. We were level at 8000 ft. We descended below 8000 ft to ensure separation. A C-141 traffic passed above and behind us. Callback conversation with reporter revealed the following information: reporter states he did not submit the report. His company takes all reports from their pilots and sends them to ASRS. He was rather abrupt and not very helpful but analyst did squeeze some information from him and applied that to the forms. He would not even guess at the miss distance, he did not remember the time of day. He did know it was VMC.

Original NASA ASRS Text

Title: MLG FLC SETS WRONG ALT WHEN CLRED TO DSND. HAS TCASII RA.

Narrative: WE WERE AT 10000 FT. WE WERE GIVEN A CLRNC TO DSND TO 9000 FT AND A HDG OF 280 DEGS TO INTERCEPT LOC RWY 26L AT ONTARIO ARPT. WE MISUNDERSTOOD THE CLRNC AND READ BACK CLRED TO 8000 FT. 8000 FT WAS SET AND ARMED IN THE FMA. AS WE INTERCEPTED THE LOC, WE GOT AN RA ON TFC TO OUR R. WE WERE LEVEL AT 8000 FT. WE DSNDED BELOW 8000 FT TO ENSURE SEPARATION. A C-141 TFC PASSED ABOVE AND BEHIND US. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES HE DID NOT SUBMIT THE RPT. HIS COMPANY TAKES ALL RPTS FROM THEIR PLTS AND SENDS THEM TO ASRS. HE WAS RATHER ABRUPT AND NOT VERY HELPFUL BUT ANALYST DID SQUEEZE SOME INFO FROM HIM AND APPLIED THAT TO THE FORMS. HE WOULD NOT EVEN GUESS AT THE MISS DISTANCE, HE DID NOT REMEMBER THE TIME OF DAY. HE DID KNOW IT WAS VMC.

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.