Date: 201306
Local time of day: 1201-1800
Location: ZMA.ARTCC, FL
Aircraft: Chancellor 414A / C414
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Flight phase: Climb
Airspace: Class E ZMA
ATC / advisory: Center ZMA
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Confusion
Anomaly: ATC Issue All Types; Airspace Violation All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
Result: General None Reported / Taken
Contributing factors: ATC Equipment / Nav Facility / Buildings; Human Factors
Primary problem: Human Factors

Narrative: I was working the RADAR position at the Nassau/Abaco Low sector(s). Several aircraft were on frequency. This sector deals with 1 Approach Control and several airports where the pilots depart VFR and then call us requesting their clearances. A C414 was the 2nd of; I believe; 5 aircraft that departed Marsh Harbor and Treasure Cay on Great Abaco Island; Bahamas. Another aircraft had departed and received their clearance along the same route as the C414 (MYAT..COMET..KDAB). However; due to RADAR limitations in the area in question; anything below 14;000 FT is questionable in terms of maintaining RADAR contact. The leading aircraft was climbing to 16;000 FT when the C414 called (airborne) for his clearance. Eventually RADAR contact with 35J was established in the vicinity of the border between the R44/61 Sector and Sector 21. I called the D-Side at Sector 21 with the intent of getting approval for issuing the clearance to 35J as the aircraft was now crossing the sector common border. I told him the aircraft was requesting the IFR clearance and thought that he said 'okay'. Then I broke my 2 basic rules; I acted on information I didn't 'know' and then I 'assumed' that he meant it was okay to issue the clearance. He gave the aircraft his clearance and shipped the aircraft to Sector 21. I went on break and was told by the D-Side instructor (OJT was being conducted) that the RADAR Controller believed that his/her airspace had been violated. I listened to the audio recording at the watch desk while watching the FALCON playback and discovered that the D21 Controller said something; but the three times that I and the watch supervisor on duty at the time listened to the audio neither one of us could ascertain exactly what was stated by the D21 Controller. There was extraneous noise in the area at the time I called D21 but it was my actions of not verifying what was said by the D21 Controller and then acting on what I BELIEVED to have been said that led to this incident. Had I SPECIFICALLY asked if I could give the aircraft the clearance; had the D21 Controller spoke more clearly; had I just RADAR identified the aircraft and coordinated that I was shipping the aircraft to the receiving sector without a clearance; and had the background noise in the area been a little less then this report would not have been necessary. But the basic 'error' was mine in 'hearing' what I was expecting to hear; my not asking the question to the D21 Controller succinctly as to obtaining approval to issue the clearance; and then my assuming that I indeed had their approval. This sector's problem will be resolved later this year when RADAR will be installed and activated at Freeport; Bahamas and RADAR coverage in the area in question will be reduced from 14;000 FT to 2;000 FT.




Synopsis: ZMA Controller described a loss of separation event when assuming information not verified regarding departures off two adjacent airports; the reporter acknowledging assumptions were in part to blame for the incident.