TCASII RA causes air carrier mlf flight crew to stop descent.

Attributes
ACN	202270
Time
Date	199203
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : bpr
State Reference	TX
Altitude	msl bound lower : 15500 msl bound upper : 17000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tower : phl
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	descent other
Route In Use	arrival other arrival star : star enroute airway : zfw
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 215 flight time total : 11500 flight time type : 5200
ASRS Report	202270
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 400
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

Descending into dfw everything was normal until TCASII gave us a TA about 10 O'clock at 7 mi, 1700 below us -- we had no idea who it might be. The controller was so busy we couldn't get a word in. TCASII gave us a 'reduce descent' cue followed quickly by a 'climb, climb' RA signal just about that time center told us of vrr traffic (Y) at the same position. We had already started evasive action, and so advised ATC. Within seconds, TCASII returned us to normal and we advised ATC we could not guarantee the crossing restriction at boids intersection. ATC acknowledged - then told the VFR (Y) traffic to expedite their descent if they could since they were right in the middle of a busy arrival route. The frustrating thing about the event was that the VFR traffic was monitoring the ATC frequency. Evidently the controller was so busy with all the inbound traffic he couldn't let us know sooner about the impending conflict. He had asked the VFR traffic (Y) earlier when they were going to start a descent, evidently realizing a potential conflict was developing. We had an experienced pilot in the jumpseat - none of us saw the VFR traffic. Part of the problem was we had high speed (assigned by ATC) (320 KTS) and high rate of descent (3000/FPM) because of descent clearance issued later than normal. Things were happening very fast. TCASII saved us from serious trouble. The ATC advisory came too late (note above we had already started evasive action.)

Original NASA ASRS Text

Title: TCASII RA CAUSES ACR MLF FLC TO STOP DSCNT.

Narrative: DSNDING INTO DFW EVERYTHING WAS NORMAL UNTIL TCASII GAVE US A TA ABOUT 10 O'CLOCK AT 7 MI, 1700 BELOW US -- WE HAD NO IDEA WHO IT MIGHT BE. THE CTLR WAS SO BUSY WE COULDN'T GET A WORD IN. TCASII GAVE US A 'REDUCE DSCNT' CUE FOLLOWED QUICKLY BY A 'CLB, CLB' RA SIGNAL JUST ABOUT THAT TIME CTR TOLD US OF VRR TFC (Y) AT THE SAME POS. WE HAD ALREADY STARTED EVASIVE ACTION, AND SO ADVISED ATC. WITHIN SECONDS, TCASII RETURNED US TO NORMAL AND WE ADVISED ATC WE COULD NOT GUARANTEE THE XING RESTRICTION AT BOIDS INTXN. ATC ACKNOWLEDGED - THEN TOLD THE VFR (Y) TFC TO EXPEDITE THEIR DSCNT IF THEY COULD SINCE THEY WERE RIGHT IN THE MIDDLE OF A BUSY ARR RTE. THE FRUSTRATING THING ABOUT THE EVENT WAS THAT THE VFR TFC WAS MONITORING THE ATC FREQ. EVIDENTLY THE CTLR WAS SO BUSY WITH ALL THE INBOUND TFC HE COULDN'T LET US KNOW SOONER ABOUT THE IMPENDING CONFLICT. HE HAD ASKED THE VFR TFC (Y) EARLIER WHEN THEY WERE GOING TO START A DSCNT, EVIDENTLY REALIZING A POTENTIAL CONFLICT WAS DEVELOPING. WE HAD AN EXPERIENCED PLT IN THE JUMPSEAT - NONE OF US SAW THE VFR TFC. PART OF THE PROBLEM WAS WE HAD HIGH SPD (ASSIGNED BY ATC) (320 KTS) AND HIGH RATE OF DSCNT (3000/FPM) BECAUSE OF DSCNT CLRNC ISSUED LATER THAN NORMAL. THINGS WERE HAPPENING VERY FAST. TCASII SAVED US FROM SERIOUS TROUBLE. THE ATC ADVISORY CAME TOO LATE (NOTE ABOVE WE HAD ALREADY STARTED EVASIVE ACTION.)

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.