Tower controller providing OJT failed to intervene in a timely manner when the developmental was lat...

Narrative:

On job training in progress; cpc in training at 'dangerous' phase; doing well; but hasn't faced many unusual situations. Cessna 172 called from west side of bravo airspace; wanting to transition through the departure corridor to east side of bravo. I advised cpc/it to bring cessna closer to the airport; exiting bravo sooner; to avoid departures. Cpc/it's transmission was not clearly understood by cessna pilot; as evidenced by pilot read back. I realized this would soon conflict with our departures wake turbulence; as the cessna would intercept the departures about 3 miles upwind; where departures are usually above 3;000 ft. I was letting the potential wake turbulence situation progress to a more obvious point; where there would still be time for the cessna to turn and avoid wake turbulence. I made the mistake of not being vigilant with the radar; focusing instead out the window. Even though I was faced directly at a B737 and the cessna; I failed to notice the B737 unusually slow climb; and cessna's rapid progress towards our departure corridor. The supervisor called our attention to the impending conflict. Next; when cpc/it made the traffic call to the cessna; it was too little; too late (approximately 1 mile lateral; 004 vertical; converging). The B737; already on departure control frequency; descended slightly to avoid a near midair collision with the cessna; most likely as a result of a TCAS alert. In other words; ATC (me) failed to separate those two aircraft. Further; our 'traffic call' to the cessna should have been a 'safety alert' call. Recommendation; the instructor needs to be vigilant to all sensory inputs (radar; windows; sounds; etc.). The instructor needs to intervene after problem becomes obvious; but well prior to situation becoming dangerous. I was a full minute late. The instructor; though not required by FAA medical; should have vision improvement devices on hand (binoculars or prescription glasses). The binoculars were shared with cpc/it. My (not required) glasses were not available.

Original NASA ASRS Text

Title: Tower Controller providing OJT failed to intervene in a timely manner when the developmental was late in insuring separation between a departure and an over flight. Controller noted lack of sensory vigilance as contributory to the event.

Narrative: On job training in progress; CPC in training at 'dangerous' phase; doing well; but hasn't faced many unusual situations. Cessna 172 called from west side of Bravo airspace; wanting to transition through the departure corridor to east side of Bravo. I advised CPC/IT to bring Cessna closer to the airport; exiting Bravo sooner; to avoid departures. CPC/IT's transmission was not clearly understood by Cessna pilot; as evidenced by pilot read back. I realized this would soon conflict with our departures wake turbulence; as the Cessna would intercept the departures about 3 miles upwind; where departures are usually above 3;000 FT. I was letting the potential wake turbulence situation progress to a more obvious point; where there would still be time for the Cessna to turn and avoid wake turbulence. I made the mistake of not being vigilant with the RADAR; focusing instead out the window. Even though I was faced directly at a B737 and the Cessna; I failed to notice the B737 unusually slow climb; and Cessna's rapid progress towards our departure corridor. The Supervisor called our attention to the impending conflict. Next; when CPC/IT made the traffic call to the Cessna; it was too little; too late (approximately 1 mile lateral; 004 vertical; converging). The B737; already on Departure Control frequency; descended slightly to avoid a NMAC with the Cessna; most likely as a result of a TCAS alert. In other words; ATC (me) failed to separate those two aircraft. Further; our 'traffic call' to the Cessna should have been a 'safety alert' call. Recommendation; the instructor needs to be vigilant to all sensory inputs (RADAR; windows; sounds; etc.). The instructor needs to intervene after problem becomes obvious; but well prior to situation becoming dangerous. I was a full minute late. The instructor; though not required by FAA medical; should have vision improvement devices on hand (binoculars or prescription glasses). The binoculars were shared with CPC/IT. My (not required) glasses were not available.

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	952952
Time
Date	201106
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Initial Climb
Flight Plan	IFR
Aircraft 2
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	VFR
Person 1
Function	Instructor Local
Qualification	Air Traffic Control Fully Certified
Person 2
Function	Supervisor / CIC
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Published Material / Policy

Tower controller providing OJT failed to intervene in a timely manner when the developmental was late in insuring separation between a departure and an over flight. Controller noted lack of sensory vigilance as contributory to the event.