ARTCC radar controller misjudges inbound holding aircraft's distance from another aircraft holding at the same altitude, over the same fix, in insufficient time to resolve conflict.

Home

Browse by month

Random

Latest

About

Contact

Attributes
ACN	412373
Time
Date	199808
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : pmm
State Reference	MI
Altitude	msl bound lower : 24000 msl bound upper : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau tower : las
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	other
Route In Use	arrival other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	arrival other arrival star : star enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 18 controller radar : 17
ASRS Report	412373
Person 2
Affiliation	government : faa
Function	controller : flight data
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance none taken : insufficient time
Consequence	faa : investigated
Miss Distance	horizontal : 27000 vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Intra Facility Coordination Failure

Narrative:

Holding at pmm VOR for WX at ord. Receiving aircraft from 2 different directions. Aircraft #1 in hold at FL250. Aircraft #2 on pmm 4 arrival from north. All altitudes FL250-310 were occupied and 2 aircraft were aimed at pmm at the same altitude. (I had already resolved 3 or 4 similar conflicts.) FL220 and FL230 were open and so I cleared aircraft #1 to FL230 to free up higher altitudes and resolve a conflict. Aircraft #2 was covered by a data block for another aircraft. Aircraft #1 was cleared through aircraft #2. As soon as I saw the conflict, I reclred aircraft #1 to climb to FL250 and expedite. The frequency was blocked and the clearance had to be restated. Then I turned aircraft #2 to a 160 degree heading. Both aircraft were told to expedite. I accepted handoffs on too many aircraft with insufficient holding altitudes available -- overlapping data blocks contributed to the error. Had I seen aircraft #2 I could have delayed descending aircraft #1 and still resolved the other conflict. I had a manual controller but a handoff controller's extra set of eyes may have seen the conflict.

Original NASA ASRS Text

Title: ARTCC RADAR CTLR MISJUDGES INBOUND HOLDING ACFT'S DISTANCE FROM ANOTHER ACFT HOLDING AT THE SAME ALT, OVER THE SAME FIX, IN INSUFFICIENT TIME TO RESOLVE CONFLICT.

Narrative: HOLDING AT PMM VOR FOR WX AT ORD. RECEIVING ACFT FROM 2 DIFFERENT DIRECTIONS. ACFT #1 IN HOLD AT FL250. ACFT #2 ON PMM 4 ARR FROM N. ALL ALTS FL250-310 WERE OCCUPIED AND 2 ACFT WERE AIMED AT PMM AT THE SAME ALT. (I HAD ALREADY RESOLVED 3 OR 4 SIMILAR CONFLICTS.) FL220 AND FL230 WERE OPEN AND SO I CLRED ACFT #1 TO FL230 TO FREE UP HIGHER ALTS AND RESOLVE A CONFLICT. ACFT #2 WAS COVERED BY A DATA BLOCK FOR ANOTHER ACFT. ACFT #1 WAS CLRED THROUGH ACFT #2. AS SOON AS I SAW THE CONFLICT, I RECLRED ACFT #1 TO CLB TO FL250 AND EXPEDITE. THE FREQ WAS BLOCKED AND THE CLRNC HAD TO BE RESTATED. THEN I TURNED ACFT #2 TO A 160 DEG HDG. BOTH ACFT WERE TOLD TO EXPEDITE. I ACCEPTED HDOFS ON TOO MANY ACFT WITH INSUFFICIENT HOLDING ALTS AVAILABLE -- OVERLAPPING DATA BLOCKS CONTRIBUTED TO THE ERROR. HAD I SEEN ACFT #2 I COULD HAVE DELAYED DSNDING ACFT #1 AND STILL RESOLVED THE OTHER CONFLICT. I HAD A MANUAL CTLR BUT A HDOF CTLR'S EXTRA SET OF EYES MAY HAVE SEEN THE CONFLICT.

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.