Date: 201512
Local time of day: 0001-0600
Location: ZBW.ARTCC, NH
Flight conditions: Marginal
Light: Night
Aircraft: Medium Large Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class E ZBW
ATC / advisory: Center ZBW
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Confusion; Communication Breakdown
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Detector: Automation Aircraft Terrain Warning
Result: Air Traffic Control Provided Assistance; Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: ATC Equipment / Nav Facility / Buildings; Airport; Airspace Structure; Procedure
Primary problem: Airspace Structure

Narrative: We normally assume control of Portland Approach Control's airspace [when they close]. The Portland controller calls us and verifies which runway the ILS is set up on and any other pertinent information about the airspace. Last night something happened and the approach controller never called. We attempted to contact the facility through several channels; but we were unsuccessful. While we attempted to contact the approach an aircraft was approaching the sector for arrival at [a local airfield]. I passed the information about the problem to the pilot and he delayed his descent until we resolved the problem.Eventually it was decided by the Operations Manager that we should assume control of Portland's airspace; but advise the pilot that we had no current information about condition and runway other than what was on the ASOS. The pilot confirmed he had weather and NOTAM information and thought the current winds were favoring a visual approach to Runway 29. I gave him direct to the airfield and waited for him to call the airport in sight. I descended the aircraft to 3;000 feet and waited for the pilot to advise he had the field in sight. Around this time the Operations Manager advised me that the ASOS was advertising ILS. When the aircraft was 10 miles from the field I advised him of its position and he said he saw the lights; but did not call the field in sight. After a couple of minutes I observed the aircraft passing over the field and I asked his intentions. He requested a vector to final and I offered to vector him to the ILS final and the pilot agreed to that.I vectored to the west on a 320 heading initially and then a 280 heading to set up his approach; he was still at 3;000 feet. My Minimum Vectoring Altitude (MVA) in that area is 2;700 feet; but close to the approach gate it rises to 3;600 feet. My plan was to turn the aircraft well before he reached the higher Minimum Vectoring Altitude. As he came abeam the approach gate I turned the aircraft south to a 170 heading and then I gave him a final turn to 120 degrees and issued the ILS approach clearance to join the localizer. My radar showed the aircraft well inside my 2;700 foot block at that time. The pilot then reported he was responding to a terrain warning and was climbing. I acknowledged the alert and waited for the pilot to say his intentions. He then told me they had the field in sight; I asked if he would like the visual approach at that time and he said yes he would. I gave him the visual approach and the pilot said he would go ahead and cancel IFR at that time. I waited a minute before terminating radar service and sending him over to advisory frequency.I informed the Operations Manager about the terrain warning and climb. I was informed that upon review it appeared that I had vectored the aircraft at 3;000 feet in the 3;600 foot MVA block. My radar data never showed the aircraft entering the higher MVA and I never received a minimum altitude alert from the computer.I would recommend refining the Minimum IFR Altitude (MIA) maps to give a finer picture of the airspace.




Synopsis: ZBW ARTCC Controller reported a CFTT event resulting from miscommunication with TRACON Control. The Controller stated his radar display indicated the aircraft was above minimums and the low altitude alerting function never activated. The aircraft continued on a visual approach and landed without incident.