Air carrier X TCASII RA took evasive action from air carrier Y.

Attributes
ACN	314570
Time
Date	199508
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : stl
State Reference	MO
Altitude	msl bound lower : 4000 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : stl tower : ffz
Operator	common carrier : air carrier
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	ATR 42
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 300 flight time total : 13000 flight time type : 1600
ASRS Report	314570
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 160 flight time total : 4500 flight time type : 1900
ASRS Report	314895
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 300 vertical : 300
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

Air carrier X descending from 5000 ft to 3000 ft, cleared for an ILS runway 12R at stl on or near glide path, on centerline. Approach control asked X if he had the heavy B747 visually. Replied 'affirmative.' approach control told the X to 'keep up your speed, and I'll let you land ahead of the heavy B747.' I assumed the commuter was close in and going to land on runway 12R ahead of us. At approximately 4000 ft, we received an alert on the TCASII, an aircraft was 700 ft directly above us and descending. At approximately 500 ft, we received RA to 'descend, descend.' I closed my throttles, rolled into a 30 degree bank to the right, and increased sink rate to approximately 1500 FPM. When the warning stopped, I rolled wings level, added power, and leveled off approximately 3000 ft. Glancing up to the left, I spotted an ATR approximately 300 ft above me and 300 ft to my left. The X then proceeded to land ahead of me on runway 12L, I landed on runway 12R. This incident makes keeping the TCASII in TA/RA very important in parallel runway operations, even though we do receive nuisance warnings occasionally. Without the TCASII, this could easily have been a midair collision. Supplemental information from acn 314895: due to radio traffic congestion momentary delay in notifying tower of traffic immediately overhead. Tower reply: he has you in sight, he's for the lda runway 12L. Replied to tower: we're descending as we have a TCASII RA for traffic! Tower reply: aircraft immediate left turn intercept lda runway 12L! Captain and flight engineer visually locate commuter aircraft coming into view on left side of aircraft, above our aircraft moving away and ahead of us. Aircraft landed approximately 1 1/2 mi ahead of our aircraft on runway 12L, we landed on runway 12R without further incident. Discontinue use of lda DME runway 12L at stl and lda DME runway 30L st louis. Aircraft are not maintaining visual contact when making parallel approachs VFR. Often being passed by commuter and GA aircraft under VFR condition, when they are told to 'maintain visual contact, cleared for the approach. Closer radar monitor of aircraft by tower when visual parallel runway use in operation.

Original NASA ASRS Text

Title: ACR X TCASII RA TOOK EVASIVE ACTION FROM ACR Y.

Narrative: ACR X DSNDING FROM 5000 FT TO 3000 FT, CLRED FOR AN ILS RWY 12R AT STL ON OR NEAR GLIDE PATH, ON CTRLINE. APCH CTL ASKED X IF HE HAD THE HVY B747 VISUALLY. REPLIED 'AFFIRMATIVE.' APCH CTL TOLD THE X TO 'KEEP UP YOUR SPD, AND I'LL LET YOU LAND AHEAD OF THE HVY B747.' I ASSUMED THE COMMUTER WAS CLOSE IN AND GOING TO LAND ON RWY 12R AHEAD OF US. AT APPROX 4000 FT, WE RECEIVED AN ALERT ON THE TCASII, AN ACFT WAS 700 FT DIRECTLY ABOVE US AND DSNDING. AT APPROX 500 FT, WE RECEIVED RA TO 'DSND, DSND.' I CLOSED MY THROTTLES, ROLLED INTO A 30 DEG BANK TO THE R, AND INCREASED SINK RATE TO APPROX 1500 FPM. WHEN THE WARNING STOPPED, I ROLLED WINGS LEVEL, ADDED PWR, AND LEVELED OFF APPROX 3000 FT. GLANCING UP TO THE L, I SPOTTED AN ATR APPROX 300 FT ABOVE ME AND 300 FT TO MY L. THE X THEN PROCEEDED TO LAND AHEAD OF ME ON RWY 12L, I LANDED ON RWY 12R. THIS INCIDENT MAKES KEEPING THE TCASII IN TA/RA VERY IMPORTANT IN PARALLEL RWY OPS, EVEN THOUGH WE DO RECEIVE NUISANCE WARNINGS OCCASIONALLY. WITHOUT THE TCASII, THIS COULD EASILY HAVE BEEN A MIDAIR COLLISION. SUPPLEMENTAL INFO FROM ACN 314895: DUE TO RADIO TFC CONGESTION MOMENTARY DELAY IN NOTIFYING TWR OF TFC IMMEDIATELY OVERHEAD. TWR REPLY: HE HAS YOU IN SIGHT, HE'S FOR THE LDA RWY 12L. REPLIED TO TWR: WE'RE DSNDING AS WE HAVE A TCASII RA FOR TFC! TWR REPLY: ACFT IMMEDIATE L TURN INTERCEPT LDA RWY 12L! CAPT AND FE VISUALLY LOCATE COMMUTER ACFT COMING INTO VIEW ON L SIDE OF ACFT, ABOVE OUR ACFT MOVING AWAY AND AHEAD OF US. ACFT LANDED APPROX 1 1/2 MI AHEAD OF OUR ACFT ON RWY 12L, WE LANDED ON RWY 12R WITHOUT FURTHER INCIDENT. DISCONTINUE USE OF LDA DME RWY 12L AT STL AND LDA DME RWY 30L ST LOUIS. ACFT ARE NOT MAINTAINING VISUAL CONTACT WHEN MAKING PARALLEL APCHS VFR. OFTEN BEING PASSED BY COMMUTER AND GA ACFT UNDER VFR CONDITION, WHEN THEY ARE TOLD TO 'MAINTAIN VISUAL CONTACT, CLRED FOR THE APCH. CLOSER RADAR MONITOR OF ACFT BY TWR WHEN VISUAL PARALLEL RWY USE IN OP.

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.