D10 controller providing OJT experienced a loss of separation event when traffic initiating a simult...

Narrative:

I was training a new developmental on AR2/AR3. We were utilizing simultaneous instrument approaches with monitors to runway 17C and runway 17L. We were given an E145 on the east downwind; air carrier X on the west downwind and another E145 on the jones dual from the northeast. AR1 had 2 airplanes on a wide left base from the northeast for runway 17L. My developmental was sitting at the AR2 scope and I was sitting at the AR3 scope which is on the other side of the developmental from the AR1 scope. I thought that the plan was for us to go first with the two downwind airplanes and then use simultaneous approaches with AR1 and our base legs. We got the east downwind in front of AR1's base leg traffic and went down to 3;000 with air carrier X. AR1 turned in at 4;000. We were late on the turn with air carrier X but I thought it still wasn't a problem because AR1 would stay at 4;000 we would turn on at 3;000 and use simultaneous approach procedures. I had moved over to the AR2 scope to instruct the developmental to slow the trailing E145 to give us room to get air carrier X in next. I then heard AR1 clear air carrier Y for the approach and switch to tower frequency. Air carrier Y was still 4 or 5 miles from the 4;000 foot glide slope capture so I thought we could still make it work as the rule is that both aircraft have to be established on the final; cleared and on tower frequency before losing vertical separation. However; air carrier Y started down immediately to the minimum descent altitude. When I observed air carrier Y leave 4;000 I canceled the approach clearance for air carrier X and broke him out to the west since he had not yet captured the final approach course. I broke several fundamental rules of air traffic by assuming everyone was on the same page. I should have been more involved in the coordination that did and did not occur. We could have easily extended either downwind to follow or taken our base leg through the final for spacing.

Original NASA ASRS Text

Title: D10 Controller providing OJT experienced a loss of separation event when traffic initiating a simultaneous approach started a descent prior to being changed to the tower frequency; the reporter indicating lack of coordination oversight as a causal factor.

Narrative: I was training a new developmental on AR2/AR3. We were utilizing simultaneous instrument approaches with monitors to Runway 17C and Runway 17L. We were given an E145 on the east downwind; Air Carrier X on the west downwind and another E145 on the Jones dual from the northeast. AR1 had 2 airplanes on a wide left base from the northeast for Runway 17L. My Developmental was sitting at the AR2 scope and I was sitting at the AR3 scope which is on the other side of the Developmental from the AR1 scope. I thought that the plan was for us to go first with the two downwind airplanes and then use simultaneous approaches with AR1 and our base legs. We got the east downwind in front of AR1's base leg traffic and went down to 3;000 with Air Carrier X. AR1 turned in at 4;000. We were late on the turn with Air Carrier X but I thought it still wasn't a problem because AR1 would stay at 4;000 we would turn on at 3;000 and use simultaneous approach procedures. I had moved over to the AR2 scope to instruct the Developmental to slow the trailing E145 to give us room to get Air Carrier X in next. I then heard AR1 clear Air Carrier Y for the approach and switch to tower frequency. Air Carrier Y was still 4 or 5 miles from the 4;000 foot glide slope capture so I thought we could still make it work as the rule is that both aircraft have to be established on the final; cleared and on tower frequency before losing vertical separation. However; Air Carrier Y started down immediately to the minimum descent altitude. When I observed Air Carrier Y leave 4;000 I canceled the approach clearance for Air Carrier X and broke him out to the west since he had not yet captured the final approach course. I broke several fundamental rules of air traffic by assuming everyone was on the same page. I should have been more involved in the coordination that did and did not occur. We could have easily extended either downwind to follow or taken our base leg through the final for spacing.

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	900064
Time
Date	201007
Local Time Of Day	1201-1800
Place
Locale Reference	DFW.Airport
State Reference	TX
Aircraft 1
Make Model Name	MD-83
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	MD-82
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Route In Use	Other Instrument Approach
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Deviation - Procedural Published Material / Policy

D10 controller providing OJT experienced a loss of separation event when traffic initiating a simultaneous approach started a descent prior to being changed to the tower frequency; the reporter indicating lack of coordination oversight as a causal factor.