<< >> NASA ASRS Report 741340, June 2007

ZID controller described near separation loss at FL290 when intrafac coordination failed and far too many assumptions were made by all involved.

Attributes
ACN	741340
Time
Date	200706
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : mie.vor
State Reference	IN
Altitude	msl single value : 29000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid.artcc
Make Model Name	EMB ERJ 135 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zid.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller time certified in position2 : 8 flight time total : 450
ASRS Report	741340
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	controller : issued alert controller : issued new clearance
Miss Distance	vertical : 1600
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Intra Facility Coordination Failure

Narrative:

Sector 88 flashed a handoff on X climbing to FL300. They had switched aircraft to sector 89 and then they realized they had traffic. Called sector 89 to have them stop the aircraft X at FL290. Sector 89 understood that sector 88 was stopping the aircraft X checks on at FL290. Sector 89 assumes action was taken and calls the traffic to them. The X remains at FL290 until they are 7 mi from the traffic. At this time sector 89 shows the X climbing out of FL290. When the aircraft is questioned they said they were given clearance to FL300. At this time conflict alert is flashing; but the traffic is 7 mi behind and out of FL310. Separation was never lost. Keys to this situation: poor coordination between sector 88/89. Both controllers assumed the other had stopped the aircraft at FL290. X pilot checks climbing to FL290. Never said they had clearance higher; so sector 89 assumes that sector 88 took care of the situation by stopping the aircraft. Separation was never lost; but shows how important clear coordination is.

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Original NASA ASRS Text

Title: ZID CTLR DESCRIBED NEAR SEPARATION LOSS AT FL290 WHEN INTRAFAC COORD FAILED AND FAR TOO MANY ASSUMPTIONS WERE MADE BY ALL INVOLVED.

Narrative: SECTOR 88 FLASHED A HDOF ON X CLBING TO FL300. THEY HAD SWITCHED ACFT TO SECTOR 89 AND THEN THEY REALIZED THEY HAD TFC. CALLED SECTOR 89 TO HAVE THEM STOP THE ACFT X AT FL290. SECTOR 89 UNDERSTOOD THAT SECTOR 88 WAS STOPPING THE ACFT X CHKS ON AT FL290. SECTOR 89 ASSUMES ACTION WAS TAKEN AND CALLS THE TFC TO THEM. THE X REMAINS AT FL290 UNTIL THEY ARE 7 MI FROM THE TFC. AT THIS TIME SECTOR 89 SHOWS THE X CLBING OUT OF FL290. WHEN THE ACFT IS QUESTIONED THEY SAID THEY WERE GIVEN CLRNC TO FL300. AT THIS TIME CONFLICT ALERT IS FLASHING; BUT THE TFC IS 7 MI BEHIND AND OUT OF FL310. SEPARATION WAS NEVER LOST. KEYS TO THIS SITUATION: POOR COORD BTWN SECTOR 88/89. BOTH CTLRS ASSUMED THE OTHER HAD STOPPED THE ACFT AT FL290. X PLT CHKS CLBING TO FL290. NEVER SAID THEY HAD CLRNC HIGHER; SO SECTOR 89 ASSUMES THAT SECTOR 88 TOOK CARE OF THE SITUATION BY STOPPING THE ACFT. SEPARATION WAS NEVER LOST; BUT SHOWS HOW IMPORTANT CLR COORD IS.

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.