D10 controller described confused similar callsign event when an aircraft accepted a descent clearan...

Narrative:

Conducting OJT on both FW1/2 and HFW1. Air carrier X was level at 11000 15 nm northwest of siler. Fw controller descended air carrier Y at siler to 6000 and switched to 118.42(AR3). Apparently air carrier X answered and began descent. The hfw developmental was highlighting air carrier X because he observed mode C at 10900 then 10800. Air carrier X reported on AR3 frequency and AR3 began inquiring about his correct frequency and location. AR3 climbed air carrier X back to 11000 and switched back to fw. Contributing factors to this deviation were: 1) both developmentals were competent; nearing the end of training. We were 'getting time' to meet minimum requirements for hfw. These circumstances conspired to make me inattentive. Instead of behaving as the 4th level of redundancy; I should have been totally focused on the operation; especially since it was an easily discernible potential for confusion in call-signs. 2) pilot inattention. Pilots have to share responsibility and maintain acute awareness. The pilot should have been aware that he had been following the similar sounding call sign for 300 miles and he should have been aware that he was 15 miles from the normal descent point which might have made him simply listen for the other aircraft to acknowledge. 3) pilots should be encouraged to question when potential confusion exists. Air carrier Y probably heard the call and knew he was at the correct descent point.

Original NASA ASRS Text

Title: D10 Controller described confused similar callsign event when an aircraft accepted a descent clearance issued to another; both ATC and the involved flight crews missed the mistake.

Narrative: Conducting OJT on both FW1/2 and HFW1. ACR X was level at 11000 15 nm NW of SILER. FW Controller descended ACR Y at SILER to 6000 and switched to 118.42(AR3). Apparently ACR X answered and began descent. The HFW developmental was highlighting ACR X because he observed mode C at 10900 then 10800. ACR X reported on AR3 frequency and AR3 began inquiring about his correct frequency and location. AR3 climbed ACR X back to 11000 and switched back to FW. Contributing factors to this deviation were: 1) Both developmentals were competent; nearing the end of training. We were 'getting time' to meet minimum requirements for HFW. These circumstances conspired to make me inattentive. Instead of behaving as the 4th level of redundancy; I should have been totally focused on the operation; especially since it was an easily discernible potential for confusion in call-signs. 2) Pilot inattention. Pilots have to share responsibility and maintain acute awareness. The pilot should have been aware that he had been following the similar sounding call sign for 300 miles and he should have been aware that he was 15 miles from the normal descent point which might have made him simply listen for the other aircraft to acknowledge. 3) Pilots should be encouraged to question when potential confusion exists. ACR Y probably heard the call and knew he was at the correct descent point.

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	859381
Time
Date	200911
Local Time Of Day	1801-2400
Place
Locale Reference	DFW.Airport
State Reference	TX
Aircraft 1
Make Model Name	Medium Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Aircraft 2
Make Model Name	Medium Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Approach Instructor
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance

D10 controller described confused similar callsign event when an aircraft accepted a descent clearance issued to another; both ATC and the involved flight crews missed the mistake.