Similar sounding call signs caused the wrong aircraft to begin a descent in another centers airspace...

Attributes
ACN	1154946
Time
Date	201403
Local Time Of Day	1201-1800
Place
Locale Reference	ZLA.ARTCC
State Reference	CA
Environment
Light	Daylight
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Aircraft 2
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (mon) 8
Events
Anomaly	ATC Issue All Types Airspace Violation All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance

Narrative:

I was working the r-side on sector xx. I had an air carrier X and air carrier Y both on frequency at the same time; both landing at las. I was not aware of the similar sounding call signs. I gave air carrier X a decent clearance to cross an intersection at FL160 250 KTS. Air carrier Y took the clearance and began descending from FL310. I did not catch this until I saw air carrier Y about a mile inside my airspace descending out of FL298. I instructed air carrier Y to maintain FL290 and reissued the descent clearance to air carrier X. I believe air carrier Y began its descent while he was still in another centers airspace.I recommend that the airlines adjust their call signs so they are not so similar or space out these flights numbers so that they are not in the same area at the same time.

Original NASA ASRS Text

Title: Similar sounding call signs caused the wrong aircraft to begin a descent in another Centers airspace.

Narrative: I was working the R-side on Sector XX. I had an Air Carrier X and Air Carrier Y both on frequency at the same time; both landing at LAS. I was not aware of the similar sounding call signs. I gave Air Carrier X a decent clearance to cross an intersection at FL160 250 KTS. Air Carrier Y took the clearance and began descending from FL310. I did not catch this until I saw Air Carrier Y about a mile inside my airspace descending out of FL298. I instructed Air Carrier Y to maintain FL290 and reissued the descent clearance to Air Carrier X. I believe Air Carrier Y began its descent while he was still in another centers airspace.I recommend that the airlines adjust their call signs so they are not so similar or space out these flights numbers so that they are not in the same area at the same time.

Data retrieved from NASA's ASRS site 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.