B757 with ZTL in holding at FL260 received TCASII TA and visually observed another aircraft at the s...

Attributes
ACN	666403
Time
Date	200507
Place
Locale Reference	atc facility : ztl.artcc
State Reference	GA
Altitude	msl single value : 26000
Environment
Flight Conditions	Mixed
Weather Elements	Thunderstorm
Light	Night
Aircraft 1
Controlling Facilities	artcc : ztl.artcc
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Route In Use	arrival star : womac
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : ztl.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 200 flight time total : 14200 flight time type : 6000
ASRS Report	666403
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : airborne critical non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 1000 vertical : 200
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

En route to atl from iad as B757; almost 4 hours late due to ZDC WX holds. Long delays combined with a cold front and associated line of thunderstorms; created a nightmare scenario with air traffic. We were assigned FL260 during a step-down descent and issued holding instructions for macey as published except for left turns due to thunderstorm activity. We were in level flight in our second turn in holding inbound to macey when the TCASII gave us a TA at 10 O'clock position which we acquired visually. As we watched; the TA became an RA and commanded a descent. The green arc on the vsi was very small; so it did not appear that we were in immediate jeopardy. About the time ZTL issued a 'climb immediately' call to B757; I disengaged the autoplt and began a very gradual descent within the parameters of the RA. I glanced at the radar screen and noted a +200 ft reading on the subject aircraft. We were visually 'padlocked' on the other aircraft and it was obvious that there would be no collision. ZTL issued us descent instructions to FL240 and the copilot advised that we were already descending in response to an RA. This came at the end of a very long (15+ hours) and stressful day. In the days before TCASII; the outcome could have been much worse. The system worked exactly as designed and avoided the need for violent maneuvering. The controller gave me a number to call to speak with a supervisor; and commented that it was their mistake. I called the supervisor after landing; mainly to pass word to the controller that we held no hard feelings and that he shouldn't 'beat himself up' too badly. He was inundated with traffic; late at night; with bad WX; missed and blocked radio calls; and under a great deal of stress. TCASII is worth every penny. It adds the extra layer of protection needed when there is human error by an over-worked professional. If we had been IMC and his radio calls had been blocked; TCASII would have saved our bacon.

Original NASA ASRS Text

Title: B757 WITH ZTL IN HOLDING AT FL260 RECEIVED TCASII TA AND VISUALLY OBSERVED ANOTHER ACFT AT THE SAME ALT; SUBSEQUENTLY RESPONDING TO A TCASII RA.

Narrative: ENRTE TO ATL FROM IAD AS B757; ALMOST 4 HRS LATE DUE TO ZDC WX HOLDS. LONG DELAYS COMBINED WITH A COLD FRONT AND ASSOCIATED LINE OF TSTMS; CREATED A NIGHTMARE SCENARIO WITH AIR TFC. WE WERE ASSIGNED FL260 DURING A STEP-DOWN DSCNT AND ISSUED HOLDING INSTRUCTIONS FOR MACEY AS PUBLISHED EXCEPT FOR L TURNS DUE TO TSTM ACTIVITY. WE WERE IN LEVEL FLT IN OUR SECOND TURN IN HOLDING INBOUND TO MACEY WHEN THE TCASII GAVE US A TA AT 10 O'CLOCK POS WHICH WE ACQUIRED VISUALLY. AS WE WATCHED; THE TA BECAME AN RA AND COMMANDED A DSCNT. THE GREEN ARC ON THE VSI WAS VERY SMALL; SO IT DID NOT APPEAR THAT WE WERE IN IMMEDIATE JEOPARDY. ABOUT THE TIME ZTL ISSUED A 'CLB IMMEDIATELY' CALL TO B757; I DISENGAGED THE AUTOPLT AND BEGAN A VERY GRADUAL DSCNT WITHIN THE PARAMETERS OF THE RA. I GLANCED AT THE RADAR SCREEN AND NOTED A +200 FT READING ON THE SUBJECT ACFT. WE WERE VISUALLY 'PADLOCKED' ON THE OTHER ACFT AND IT WAS OBVIOUS THAT THERE WOULD BE NO COLLISION. ZTL ISSUED US DSCNT INSTRUCTIONS TO FL240 AND THE COPLT ADVISED THAT WE WERE ALREADY DSNDING IN RESPONSE TO AN RA. THIS CAME AT THE END OF A VERY LONG (15+ HRS) AND STRESSFUL DAY. IN THE DAYS BEFORE TCASII; THE OUTCOME COULD HAVE BEEN MUCH WORSE. THE SYS WORKED EXACTLY AS DESIGNED AND AVOIDED THE NEED FOR VIOLENT MANEUVERING. THE CTLR GAVE ME A NUMBER TO CALL TO SPEAK WITH A SUPVR; AND COMMENTED THAT IT WAS THEIR MISTAKE. I CALLED THE SUPVR AFTER LNDG; MAINLY TO PASS WORD TO THE CTLR THAT WE HELD NO HARD FEELINGS AND THAT HE SHOULDN'T 'BEAT HIMSELF UP' TOO BADLY. HE WAS INUNDATED WITH TFC; LATE AT NIGHT; WITH BAD WX; MISSED AND BLOCKED RADIO CALLS; AND UNDER A GREAT DEAL OF STRESS. TCASII IS WORTH EVERY PENNY. IT ADDS THE EXTRA LAYER OF PROTECTION NEEDED WHEN THERE IS HUMAN ERROR BY AN OVER-WORKED PROFESSIONAL. IF WE HAD BEEN IMC AND HIS RADIO CALLS HAD BEEN BLOCKED; TCASII WOULD HAVE SAVED OUR BACON.

Data retrieved from NASA's ASRS site as of January 2009 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.

B757 with ZTL in holding at FL260 received TCASII TA and visually observed another aircraft at the same altitude; subsequently responding to a TCASII RA.