Date: 201504
Local time of day: 1201-1800
Location: A90.TRACON, NH
Light: Daylight
Aircraft: Small Aircraft; High Wing; 1 Eng; Fixed Gear
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Flight phase: Cruise
Airspace: Class E ZBW
ATC / advisory: TRACON A90
Reporter organization: Government
Reporter function: Approach; Departure
Human factors: Distraction; Troubleshooting
Anomaly: ATC Issue All Types
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance
Contributing factors: ATC Equipment / Nav Facility / Buildings; Aircraft; Equipment / Tooling
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: Aircraft X departed CON on IFR training flight with approaches at LCI and CON.  The aircraft departed with the transponder possibly in the off position.  I had the aircraft recycle and verify it was on.  I was able to get a very weak radar hit and identify the aircraft.  As the aircraft was vectored the radar contact was intermittent despite being in an area of good coverage.  Multiple times the data tag went into a coast function. Once the data tag did not auto re-position back to the aircraft despite a good radar hit being displayed in close proximity; 1 nm; to the data tag in coast.  The tag then timed out and went to my coast suspend list and I had to manual re-position the tag back onto the aircraft from the coast suspend list.  A few minutes later I cleared the aircraft for an approach at LCI and immediately began a position relief briefing.  By the time the relief briefing had finished the aircraft again had gone into a coast function and the data tag timed out despite a target being observed nearby. I advised the relieving controller of the data block issue to which she replied; 'Thank you; I would have completely forgot about him' as it is an approach in an area of low traffic and mountainous terrain.  It was expected that radar coverage was going to be lost again shortly. I agree to share this report. A work around fix to this particular issue would have been to put the ZZ function on the aircraft when the data tag started having coverage issues but that would have blocked the speed from being visible and would just have masked the larger problem of an IFR aircraft in an area of usually good coverage that is unable to maintain radar contact and as a result the data tag dropping into the coast suspend list.  The tag stayed in a coast function for the minimum required time according to the orders; which our facility has the Standard Terminal Automation Replacement System (STARS) display set to; which I believe is 30 seconds.  I see no benefit at setting the time so low and would recommend increasing it to as long a time as possible in areas not in the immediate vicinity of a towered airport. This was a perfect example of how 30 seconds is an insufficient time because the position relief briefing greatly increased scanned time; resulting in the tag dropping off the scope without either of us immediately noticing.  It would seem better to err on the side of caution and to have to manually remove a coast tag if you don't want it displayed rather than having to always re-position it when it moves to the coast suspend list (outside the normal scan) and manually insert the ZZ function to keep it displayed.  In the mountainous area where this occurred it would have been very easy to completely forget that this aircraft was out there without that visual clue.




Synopsis: A Boston TRACON (A90) Controller reports of having difficulty with an aircraft transponder. The Controller stated the data tag would go into a coast mode and he had to tag up the aircraft often.