Large Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2.5
Distraction; Confusion; Workload
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Airspace Structure; Procedure
Busy session on final landing the Expressway Visual Approach to Runway 31.  My final started to get backed up and I needed to vector northbound over Manhattan for spacing.  Aircraft X was eastbound over Manhattan at 3;000 feet when I cleared him for the approach.  The approach clearance instructed him to cross DIALS; which was about 3 miles east of his position; at or above 2;500 feet.  In between this aircraft and DIALS; Aircraft Y was level at 1;900 feet at the border between LGA Tower's airspace and my own.  Aircraft X descended to 2;500 feet; directly overhead of Aircraft Y at 1;900 feet.When LGA is landing left traffic to Runway 4 the Tower may only work VFR aircraft at 2;000 feet up to the LGA 240 radial.  When LGA is landing left traffic to Runway 31 the Tower may work VFR aircraft at 2;000 feet up the LGA 230 radial.  Even though it's only a 10 degree difference; in such tight airspace it makes a very big difference.  If Aircraft Y was west of the LGA 240 radial there would not have been a problem.  I recommend the Tower's airspace be restricted to the LGA 240 radial when landing left traffic to Runway 3.
N90 Controller makes a request to change airspace related to IFR operations and VFR Helicopter operations.