Air carrier Y had less than standard separation from air carrier X. System error.

Attributes
ACN	299184
Time
Date	199503
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : slc
State Reference	UT
Altitude	msl bound lower : 19000 msl bound upper : 19000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc tracon : slc tower : oma
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 5
ASRS Report	299184
Person 2
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	none taken : anomaly accepted
Consequence	faa : investigated
Miss Distance	horizontal : 24000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Inter Facility Coordination Failure

Narrative:

While working a departure vector ZLC, slc departure control handed off 2 aircraft on slightly divergent courses (less than 12 degrees) with less than 5 mi separation, but more than 3 mi. The first aircraft air carrier X came up on my frequency and was climbed to FL290, the second aircraft air carrier Y was coordinated as being slowed to 250 KTS so as to increase the lateral separation. The aircraft were shipped to center frequency with no vertical separation and less than 5 mi lateral, a loss of separation with the speed difference separation was achieved quickly and no other actions were needed. The FAA, I believe, needs to allow more use of transitional separation from approach to center and also more use of speed and divergent separation between aircraft in a radar environment instead of the strict use of 5 mi lateral separation. With these 2 aircraft being same direction and 50 KTS true airspeed and 80 KTS over the ground speed difference the 2 aircraft were never in danger of actually being a near miss or coming closer together than the original 3 mi.

Original NASA ASRS Text

Title: ACR Y HAD LTSS FROM ACR X. SYS ERROR.

Narrative: WHILE WORKING A DEP VECTOR ZLC, SLC DEP CTL HANDED OFF 2 ACFT ON SLIGHTLY DIVERGENT COURSES (LESS THAN 12 DEGS) WITH LESS THAN 5 MI SEPARATION, BUT MORE THAN 3 MI. THE FIRST ACFT ACR X CAME UP ON MY FREQ AND WAS CLBED TO FL290, THE SECOND ACFT ACR Y WAS COORDINATED AS BEING SLOWED TO 250 KTS SO AS TO INCREASE THE LATERAL SEPARATION. THE ACFT WERE SHIPPED TO CTR FREQ WITH NO VERT SEPARATION AND LESS THAN 5 MI LATERAL, A LOSS OF SEPARATION WITH THE SPD DIFFERENCE SEPARATION WAS ACHIEVED QUICKLY AND NO OTHER ACTIONS WERE NEEDED. THE FAA, I BELIEVE, NEEDS TO ALLOW MORE USE OF TRANSITIONAL SEPARATION FROM APCH TO CTR AND ALSO MORE USE OF SPD AND DIVERGENT SEPARATION BTWN ACFT IN A RADAR ENVIRONMENT INSTEAD OF THE STRICT USE OF 5 MI LATERAL SEPARATION. WITH THESE 2 ACFT BEING SAME DIRECTION AND 50 KTS TRUE AIRSPD AND 80 KTS OVER THE GND SPD DIFFERENCE THE 2 ACFT WERE NEVER IN DANGER OF ACTUALLY BEING A NEAR MISS OR COMING CLOSER TOGETHER THAN THE ORIGINAL 3 MI.

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.