Aircraft X TCASII RA with aircraft Y when standard separation existed. Flawed TCASII logic.

Attributes
ACN	269680
Time
Date	199404
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : fll
State Reference	FL
Altitude	msl bound lower : 5000 msl bound upper : 6000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mia
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent : approach other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
ASRS Report	269680
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : undershoot conflict : airborne less severe non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	other
Consequence	Other
Miss Distance	vertical : 1000
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Aircraft X, B727, climbing to assigned altitude of 5000 ft. Aircraft Y B727, level at 6000 ft on downwind to fll. X advised he was receiving a TCASII RA to descend. I had previously issued traffic to X, which he acknowledged. After X advised me he was responding to RA, I once again advised him the traffic was 1000 ft above his assigned altitude. Miami approach airspace contains many areas where aircraft on downwind are 1000 ft above departure aircraft. Even though required separation exists, there have been countless incidents of TCASII RA's in this situation. Fortunately, there have been few incidents where separation is lost. Miami should be added to the list of areas where the FAA has recommended TCASII be used in the TA mode only.

Original NASA ASRS Text

Title: ACFT X TCASII RA WITH ACFT Y WHEN STANDARD SEPARATION EXISTED. FLAWED TCASII LOGIC.

Narrative: ACFT X, B727, CLBING TO ASSIGNED ALT OF 5000 FT. ACFT Y B727, LEVEL AT 6000 FT ON DOWNWIND TO FLL. X ADVISED HE WAS RECEIVING A TCASII RA TO DSND. I HAD PREVIOUSLY ISSUED TFC TO X, WHICH HE ACKNOWLEDGED. AFTER X ADVISED ME HE WAS RESPONDING TO RA, I ONCE AGAIN ADVISED HIM THE TFC WAS 1000 FT ABOVE HIS ASSIGNED ALT. MIAMI APCH AIRSPACE CONTAINS MANY AREAS WHERE ACFT ON DOWNWIND ARE 1000 FT ABOVE DEP ACFT. EVEN THOUGH REQUIRED SEPARATION EXISTS, THERE HAVE BEEN COUNTLESS INCIDENTS OF TCASII RA'S IN THIS SIT. FORTUNATELY, THERE HAVE BEEN FEW INCIDENTS WHERE SEPARATION IS LOST. MIAMI SHOULD BE ADDED TO THE LIST OF AREAS WHERE THE FAA HAS RECOMMENDED TCASII BE USED IN THE TA MODE ONLY.

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.