ARTCC radar controller descended a cpr light transport through an altitude occupied by an air carrier aircraft, discovered his error and tried to stop the light transport. The light transport got a TCASII alert and the controller turned him. But separation was lost anyway.

Home

Browse by month

Random

Latest

About

Contact

Attributes
ACN	369766
Time
Date	199705
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ags
State Reference	GA
Altitude	msl bound lower : 29000 msl bound upper : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	general aviation : corporate
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 60 flight time total : 5500
ASRS Report	369766
Person 2
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance flight crew : took evasive action other
Consequence	Other
Miss Distance	horizontal : 13500 vertical : 600
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

After initially being cleared from FL350 to FL290 and then on down to FL240, we encountered a TCASII warning to slow descent rate upon which we complied. The controller then instructed us to turn left 30 degrees of which we also complied and advised him again we had a TCASII warning and would be leveling. Although we never saw the other aircraft visually the TCASII did show it at 2 - 2 1/2 mi and 600 ft of vertical separation. No further action was required. The controller told us it was his mistake repeatedly. In the future, if other aircraft hear others advising of a TCASII warning to center and center giving heading instructions, they should delay their xmissions until the potential for conflict is over. Frequency congestion can be a factor in aircraft or center not receiving timely information.

Original NASA ASRS Text

Title: ARTCC RADAR CTLR DSNDED A CPR LTT THROUGH AN ALT OCCUPIED BY AN ACR ACFT, DISCOVERED HIS ERROR AND TRIED TO STOP THE LTT. THE LTT GOT A TCASII ALERT AND THE CTLR TURNED HIM. BUT SEPARATION WAS LOST ANYWAY.

Narrative: AFTER INITIALLY BEING CLRED FROM FL350 TO FL290 AND THEN ON DOWN TO FL240, WE ENCOUNTERED A TCASII WARNING TO SLOW DSCNT RATE UPON WHICH WE COMPLIED. THE CTLR THEN INSTRUCTED US TO TURN L 30 DEGS OF WHICH WE ALSO COMPLIED AND ADVISED HIM AGAIN WE HAD A TCASII WARNING AND WOULD BE LEVELING. ALTHOUGH WE NEVER SAW THE OTHER ACFT VISUALLY THE TCASII DID SHOW IT AT 2 - 2 1/2 MI AND 600 FT OF VERT SEPARATION. NO FURTHER ACTION WAS REQUIRED. THE CTLR TOLD US IT WAS HIS MISTAKE REPEATEDLY. IN THE FUTURE, IF OTHER ACFT HEAR OTHERS ADVISING OF A TCASII WARNING TO CTR AND CTR GIVING HDG INSTRUCTIONS, THEY SHOULD DELAY THEIR XMISSIONS UNTIL THE POTENTIAL FOR CONFLICT IS OVER. FREQ CONGESTION CAN BE A FACTOR IN ACFT OR CTR NOT RECEIVING TIMELY INFO.

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.