<< >> NASA ASRS Report 428650, February 1999

ZDV flight data controller (D side) observes radar controller vector, but failed to maintain radar separation between 2 air carrier jets inbound to den.

Attributes
ACN	428650
Time
Date	199902
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	intersection : tomsn
State Reference	CO
Altitude	msl single value : 19000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : flight data
Qualification	controller : non radar
Experience	controller non radar : 12 controller radar : 12
ASRS Report	428650
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 21
ASRS Report	428651
Events
Anomaly	conflict : airborne less severe non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	faa : investigated
Miss Distance	horizontal : 24000 vertical : 400
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X and air carrier Y were den arrs cleared to FL190 and speed reduced to 250 KTS. Aircraft were converging and vectors to achieve required separation did not work. Supplemental information from acn 428651: air carrier X and air carrier Y (2 B727's) were both assigned crossing restrs over tomsn intersection of FL190 and 250 KTS. Both were switched to den approach at assigned altitude and speed. The first aircraft slowed and took 1 min 15 seconds to change frequency causing the back aircraft to catch the first. If timely communications would've occurred, the situation would not have developed.

Related reports:

• Sct controller observes a conflicting situation between a B7...
• Lgb controller observes tower certification incident between...
• ZID associate controller observes conflict between climbing ...
• Teb tower observes situation between local controller and gr...
• D01 relieving controller observes conflict between en route ...

	Enter your search terms Submit search form
	Web www.37000feet.com

Original NASA ASRS Text

Title: ZDV FLT DATA CTLR (D SIDE) OBSERVES RADAR CTLR VECTOR, BUT FAILED TO MAINTAIN RADAR SEPARATION BTWN 2 ACR JETS INBOUND TO DEN.

Narrative: ACR X AND ACR Y WERE DEN ARRS CLRED TO FL190 AND SPD REDUCED TO 250 KTS. ACFT WERE CONVERGING AND VECTORS TO ACHIEVE REQUIRED SEPARATION DID NOT WORK. SUPPLEMENTAL INFO FROM ACN 428651: ACR X AND ACR Y (2 B727'S) WERE BOTH ASSIGNED XING RESTRS OVER TOMSN INTXN OF FL190 AND 250 KTS. BOTH WERE SWITCHED TO DEN APCH AT ASSIGNED ALT AND SPD. THE FIRST ACFT SLOWED AND TOOK 1 MIN 15 SECONDS TO CHANGE FREQ CAUSING THE BACK ACFT TO CATCH THE FIRST. IF TIMELY COMS WOULD'VE OCCURRED, THE SIT WOULD NOT HAVE DEVELOPED.

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.