D10 controller described near loss of separation when failing to note the speed over-take situation ...

Narrative:

Air carrier X departed on a RNAV SID followed closely by air carrier Y. Traffic was unusually complex due to the fact that there were three sectors were combined into one. Aircraft were utilizing three frequencies simultaneously. I believe that the aircraft hadn't been given enough space initially; but the second aircraft was not doing the same speed as the first. He was considerably faster and I didn't realize that fact until a few miles into the flight. Recommendation; an assigned speed needs to be put into the SID instead of a minimum speed to ensure that all aircraft are utilizing the same speed in this critical phase of flight; so controllers don't have to use critical time to police speeds in a quickly changing environment such as a departure sector.

Original NASA ASRS Text

Title: D10 Controller described near loss of separation when failing to note the speed over-take situation developing between two successive departures; reporter suggested published assigned speeds on the SIDs.

Narrative: Air Carrier X departed on a RNAV SID followed closely by Air Carrier Y. Traffic was unusually complex due to the fact that there were three sectors were combined into one. Aircraft were utilizing three frequencies simultaneously. I believe that the aircraft hadn't been given enough space initially; but the second aircraft was not doing the same speed as the first. He was considerably faster and I didn't realize that fact until a few miles into the flight. Recommendation; an assigned speed needs to be put into the SID instead of a minimum speed to ensure that all aircraft are utilizing the same speed in this critical phase of flight; so controllers don't have to use critical time to police speeds in a quickly changing environment such as a departure sector.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	865941
Time
Date	200912
Local Time Of Day	1201-1800
Place
Locale Reference	D10.TRACON
State Reference	TX
Aircraft 1
Make Model Name	Light Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Climb
Route In Use	SID N/S
Flight Plan	IFR
Aircraft 2
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Climb
Route In Use	SID N/S
Flight Plan	IFR
Person 1
Function	Departure
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types

D10 controller described near loss of separation when failing to note the speed over-take situation developing between two successive departures; reporter suggested published assigned speeds on the sids.