TCASII warns flight crew that they may have descended below assigned altitude.

Attributes
ACN	233183
Time
Date	199302
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : mia
State Reference	FL
Altitude	msl bound lower : 8650 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mia
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 2200 flight time type : 240
ASRS Report	233183
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp pilot : cfi
Experience	flight time last 90 days : 250 flight time total : 11500 flight time type : 700
ASRS Report	233179
Events
Anomaly	conflict : airborne less severe non adherence : clearance non adherence other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 3000 vertical : 650
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Pilot Deviation other

Narrative:

On vectors to ILS 9R at mia, when passing 8750 ft on descent, the TCASII gave us a traffic warning. We leveled at 8650 ft and TCASII showed traffic to be 700 ft below us. We then asked approach if we were cleared to 8000 ft. Approach replied, no, 9000 ft. We told approach that we both understood the clearance from 10000 ft was to 8000 ft and had acknowledged so. Approach subsequently (5-7 seconds later) cleared us lower (4000 ft I believe) with no comment. End of incident. First officer had acknowledged descent to 8000 from 10000 and set it in altitude window. Captain concurred. Possible contributing factor was an air carrier flight in vicinity.

Original NASA ASRS Text

Title: TCASII WARNS FLC THAT THEY MAY HAVE DSNDED BELOW ASSIGNED ALT.

Narrative: ON VECTORS TO ILS 9R AT MIA, WHEN PASSING 8750 FT ON DSCNT, THE TCASII GAVE US A TFC WARNING. WE LEVELED AT 8650 FT AND TCASII SHOWED TFC TO BE 700 FT BELOW US. WE THEN ASKED APCH IF WE WERE CLRED TO 8000 FT. APCH REPLIED, NO, 9000 FT. WE TOLD APCH THAT WE BOTH UNDERSTOOD THE CLRNC FROM 10000 FT WAS TO 8000 FT AND HAD ACKNOWLEDGED SO. APCH SUBSEQUENTLY (5-7 SECONDS LATER) CLRED US LOWER (4000 FT I BELIEVE) WITH NO COMMENT. END OF INCIDENT. FO HAD ACKNOWLEDGED DSCNT TO 8000 FROM 10000 AND SET IT IN ALT WINDOW. CAPT CONCURRED. POSSIBLE CONTRIBUTING FACTOR WAS AN ACR FLT IN VICINITY.

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.