<< >> NASA ASRS Report 187830, August 1991

Air carrier X had airborne conflict with aircraft Y VFR below the TCA. See and avoid concept. TCASII TA RA. Evasive action taken climb.

Attributes
ACN	187830
Time
Date	199108
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dfw
State Reference	TX
Altitude	msl bound lower : 4000 msl bound upper : 4300
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dfw
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time total : 20000
ASRS Report	187830
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : undershoot 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 : 5000 vertical : 100
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

Air carrier X inbound on dfw 31R localizer. Cleared to descend to 4000 ft. During descent received TCASII alert (yellow) of traffic. Target was at 12 O'clock and closing. Target remained at 12 O'clock on the localizer. Resolution alert (RA) appeared at normal interval, vertical separation indicated from 300 ft down to 100 ft less than 1 mi. During this period our aircraft was descending through 4800 ft toward 4000 ft. At 4100 ft we made decision to climb in accordance with RA back to 4300-4400 ft. After clearing TCASII target resumed approach. During the above mentioned phase of flight, we were in clouds visibility 0. During this time I asked dfw approach controller if he had traffic that I showed on TCASII. His reply was 'slow to 150 KTS.' I repeated my question, rather emphatically. Reply was 'oh yeah, he's VFR into love field.' my reply was 'he's not VFR at 4000 ft.' no reply from controller. He seemed totally unconcerned.

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Original NASA ASRS Text

Title: ACR X HAD AIRBORNE CONFLICT WITH ACFT Y VFR BELOW THE TCA. SEE AND AVOID CONCEPT. TCASII TA RA. EVASIVE ACTION TAKEN CLB.

Narrative: ACR X INBOUND ON DFW 31R LOC. CLRED TO DSND TO 4000 FT. DURING DSCNT RECEIVED TCASII ALERT (YELLOW) OF TFC. TARGET WAS AT 12 O'CLOCK AND CLOSING. TARGET REMAINED AT 12 O'CLOCK ON THE LOC. RESOLUTION ALERT (RA) APPEARED AT NORMAL INTERVAL, VERT SEPARATION INDICATED FROM 300 FT DOWN TO 100 FT LESS THAN 1 MI. DURING THIS PERIOD OUR ACFT WAS DSNDING THROUGH 4800 FT TOWARD 4000 FT. AT 4100 FT WE MADE DECISION TO CLB IN ACCORDANCE WITH RA BACK TO 4300-4400 FT. AFTER CLRING TCASII TARGET RESUMED APCH. DURING THE ABOVE MENTIONED PHASE OF FLT, WE WERE IN CLOUDS VISIBILITY 0. DURING THIS TIME I ASKED DFW APCH CTLR IF HE HAD TFC THAT I SHOWED ON TCASII. HIS REPLY WAS 'SLOW TO 150 KTS.' I REPEATED MY QUESTION, RATHER EMPHATICALLY. REPLY WAS 'OH YEAH, HE'S VFR INTO LOVE FIELD.' MY REPLY WAS 'HE'S NOT VFR AT 4000 FT.' NO REPLY FROM CTLR. HE SEEMED TOTALLY UNCONCERNED.

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.