Pct controller experienced a loss of separation event between two arrivals to iad. The reporter list...

Attributes
ACN	1028741
Time
Date	201208
Local Time Of Day	1801-2400
Place
Locale Reference	IAD.Airport
State Reference	DC
Aircraft 1
Make Model Name	Regional Jet 700 ER/LR (CRJ700)
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Vectors STAR GIBBZ RNAV
Flight Plan	IFR
Aircraft 2
Make Model Name	HS 125 Series
Operating Under FAR Part	Part 91
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Deviation - Procedural Published Material / Policy

Narrative:

A hawker was on a vector for runway 01C at 3;000 ft and a crj was on downwind for runway 01L. I turned the crj on a base heading a descended them to 3;000 ft. I had planned on the crj turning in front of the hawker; however due to the new gibbz RNAV arrival; the crj was further west and heading southwest. This resulted in the crj making a wider turn than I'm used too; because of this wide turn I lost separation with the crj and the hawker prior to the crj having the airport in sight. I would recommend moving the fix siyob on the gibbz arrival to the west as this would allow a heading between siyob and mikej that would parallel the final approach course. Also; with the new arrival the airspace boundary with final and tilly sector is further south and this makes it harder to descend the arrivals on downwind and turn towards the airport.

Original NASA ASRS Text

Title: PCT Controller experienced a loss of separation event between two arrivals to IAD. The reporter listed the new GIBBS RNAV STAR's track as contributing to the event.

Narrative: A Hawker was on a vector for Runway 01C at 3;000 FT and a CRJ was on downwind for Runway 01L. I turned the CRJ on a base heading a descended them to 3;000 FT. I had planned on the CRJ turning in front of the Hawker; however due to the new GIBBZ RNAV arrival; the CRJ was further west and heading southwest. This resulted in the CRJ making a wider turn than I'm used too; because of this wide turn I lost separation with the CRJ and the Hawker prior to the CRJ having the airport in sight. I would recommend moving the fix SIYOB on the GIBBZ arrival to the west as this would allow a heading between SIYOB and MIKEJ that would parallel the final approach course. Also; with the new arrival the airspace boundary with final and Tilly Sector is further south and this makes it harder to descend the arrivals on downwind and turn towards the airport.

Data retrieved from NASA's ASRS site as of July 2013 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.

Pct controller experienced a loss of separation event between two arrivals to iad. The reporter listed the new gibbs RNAV STAR's track as contributing to the event.