Date: 201812
Local time of day: 1801-2400
Location: ZNY.ARTCC, NY
Aircraft: Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Flight plan: IFR
Flight phase: Cruise
Airspace: Class A ZNY
ATC / advisory: Center ZNY; TRACON N90
Second aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Situational Awareness
Second reporter function: Approach
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
Contributing factors: ATC Equipment / Nav Facility / Buildings; Human Factors
Primary problem: Human Factors

Narrative: New York TRACON approved Aircraft X over LENDY. Aircraft X was inbound to FRG. New York TRACON requested that Aircraft X be separated with other LENDY traffic by altitude. I descended Aircraft X to FL180. FL180 was usable. Aircraft X was flashing to the TRACON in order to effect the handoff. When Aircraft X was about 2 miles from LENDY I called the TRACON over the landline for a handoff. I got no response. I called the TRACON again over the landline when Aircraft X was over LENDY. I got no response. At that time I vectored Aircraft X to a 330 heading and I advised the pilot it was because I was unable to affect the handoff with the TRACON. The TRACON did accept the handoff on Aircraft Y which was currently about 5 miles northwest of LENDY. Aircraft Y was tracking to LENDY at FL190. The TRACON was in communication with Aircraft Y. When Aircraft Y was just passed LENDY I observed Aircraft Y descend out of FL190. At this point I called the TRACON again and yelled over the line that there was traffic just southeast of Aircraft Y. Aircraft Y and Aircraft X came within 3 miles and a thousand feet of each other. I asked Aircraft X if he sees the traffic. Aircraft X advised me that the traffic was abeam his position. The TRACON later called me over the landline and asked me to call them over the landline for a line check. They said they were now able to hear me. This event happened for one of two reasons. The TRACON did not hear me when I called them over the landline and the aircraft was not flashing on their end due to some kind of equipment misuse or malfunction. Or the TRACON ignored my calls over the landline and ignored the aircraft that was flashing to them to affect the handoff. In either case Aircraft Y should not have been descended thru Aircraft X. Clearly there was some kind of lack of awareness of Aircraft X position when the descent clearance was issued to Aircraft Y. This is human error. Aircraft should not be descended through other aircraft regardless if you have the handoff on them or not. Controllers need to be aware of any target on their scope that could affect the operation. If there was an equipment malfunction and the landline was faulty it needs to be addressed ASAP as verbal communication between facilities is vital to our operation. If the TRACON could not see the aircraft flashing at them due to some kind of equipment malfunction; it needs to be addressed why they were not able to see the aircraft flashing at them.


Second narrative: Aircraft Y was fed to me at 190. Per LOA; I have control for descent and limited turns. I turned and descended. NY Center had an aircraft under him at 180. They had been trying to handoff to the wrong scope. The landline calls never came through the speaker because the speaker was muted and no one knew. This was the closest I have ever seen two aircraft in my years. The TCAS saved lives today.1-I am in shock how STARS is not used to its fullest potential! N90 needs a full time STARS rep. Most people here are completely unaware of the functionality available. This may have been an automation fail in the STARS. I do not know.2-I think the NY Center Controller or all of that sectors controllers need refresher training on the letter of agreement. They may not realize those aircraft are my control to descend therefore they must not switch them to me until there is no traffic in the way. I have seen and missed their traffic in the past. I just missed this one in my scan. But they are not being diligent if I have seen this more than once.3-If this was an ERAM fail in automation; that needs to be addressed.4-A procedure may be needed here to mandate no one turn the speaker volume to mute; or put a modulator on the knob to prohibit this.


Synopsis: New York Center and New York TRACON Controllers reported a loss of separation due to a handoff not being made to the correct sector and the landline speaker being muted.