Approach controller providing OJT described a loss of separation event when failing to intervene in ...

Narrative:

I was trainer on position with trainee. Aircraft X departed for a local IFR flight plan to a nearby airport and back. Trainee gave a 040 heading which was too far left for their destination; but not unusual for our approach configuration. I noted that this was close to the VOR/DME track for aircraft Y inbound; but would likely slowly diverge. Tower supervisor called down after inbound aircraft Y overshot turn from arc to final and that we're going to lose 3 mile separation. This drew trainee's attention to the problem and he assigned a heading of 090; which I thought to be sufficient. Aircraft tracked to the east-northeast (about 060 heading for 4 miles before turning to a 090 heading). There was insufficient time to monitor the track and make a correction before separation was lost. Aircraft X was pointed away from the traffic; but lost 3 mile separation and due to the 060 track we did not have passing/diverging rule (needed at least 45 degrees; but actual track of plane gave us only 35 degrees). My best guess is that the plane's directional gyro was off from compass. This was my responsibility. I let the trainee have too much leeway so that his correction was hoped for; but did not ensure separation. There was an equipment side to this issue; our radar scopes do not show trails; so much of our directional guidance on targets is based on remembering where the target was. Clearly on the replay; which has trails and history; we could see that the initial 040 heading actually tracked about a 020 heading. Winds at 3;000 ft had not been affecting aircraft on base or approach headings much; so I expected this aircraft to track about 035 to 040. As he slowly converged with the approach course and appeared to be about 1-1/2 miles from final; it was easy to forget that he had been about 2-1/2 miles away from it when he first made the turn. This is a very simple tool and we have it available upstairs on our BRITE scope; but not here in the TRACON. I think that the wayward heading would have been obvious. However; this is a known deficiency and with the limitations of our equipment I should not have allowed this to run this close.

Original NASA ASRS Text

Title: Approach Controller providing OJT described a loss of separation event when failing to intervene in a timely manner; alleging that RADAR equipment lacked 'trailing' information which would have provided needed course information.

Narrative: I was trainer on position with trainee. Aircraft X departed for a local IFR flight plan to a nearby airport and back. Trainee gave a 040 heading which was too far left for their destination; but not unusual for our approach configuration. I noted that this was close to the VOR/DME track for aircraft Y inbound; but would likely slowly diverge. Tower Supervisor called down after inbound aircraft Y overshot turn from arc to final and that we're going to lose 3 mile separation. This drew trainee's attention to the problem and he assigned a heading of 090; which I thought to be sufficient. Aircraft tracked to the east-northeast (about 060 heading for 4 miles before turning to a 090 heading). There was insufficient time to monitor the track and make a correction before separation was lost. Aircraft X was pointed away from the traffic; but lost 3 mile separation and due to the 060 track we did not have passing/diverging rule (needed at least 45 degrees; but actual track of plane gave us only 35 degrees). My best guess is that the plane's directional gyro was off from compass. This was my responsibility. I let the trainee have too much leeway so that his correction was hoped for; but did not ensure separation. There was an equipment side to this issue; our RADAR scopes do not show trails; so much of our directional guidance on targets is based on remembering where the target was. Clearly on the replay; which has trails and history; we could see that the initial 040 heading actually tracked about a 020 heading. Winds at 3;000 FT had not been affecting aircraft on base or approach headings much; so I expected this aircraft to track about 035 to 040. As he slowly converged with the approach course and appeared to be about 1-1/2 miles from final; it was easy to forget that he had been about 2-1/2 miles away from it when he first made the turn. This is a very simple tool and we have it available upstairs on our BRITE scope; but not here in the TRACON. I think that the wayward heading would have been obvious. However; this is a known deficiency and with the limitations of our equipment I should not have allowed this to run this close.

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	983795
Time
Date	201112
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	PA-28R Cherokee Arrow All Series
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Flight Plan	IFR
Person 1
Function	Departure Approach Instructor
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

Approach controller providing OJT described a loss of separation event when failing to intervene in a timely manner; alleging that radar equipment lacked 'trailing' information which would have provided needed course information.