Date: 201410
Local time of day: 1201-1800
Location: LGA.Airport, NY
Light: Daylight
Aircraft: Medium Large Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Tower LGA
Second aircraft: Large Transport
Reporter organization: Government
Reporter function: Ground
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Confusion; Communication Breakdown; Distraction
Second reporter function: Coordinator
Anomaly: Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Detector: Person Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Separated Traffic
Contributing factors: Procedure; Human Factors
Primary problem: Procedure

Narrative: I was working Ground Control. The runway configuration at LGA was the localizer approach landing Runway 31; departing Runway 4. Traffic departing for BOS required coordination with N90 TMU for approval due to a large mile in trail restriction. Aircraft X called requesting taxi instructions for departure. I advised the pilot that his flight would be delayed and a release time was coordinated. After the pilot acknowledged the information; I taxied him onto Taxiway 'A'; 'G' and instructed him to hold short of Runway 4 at Taxiway 'G.' while Aircraft X was holding short of Runway 4 at 'G'; I checked the brite to see where the next arrival was on the final and then scanned out the window to see if Local had any departures in position or on takeoff roll.The closest arrival on the radar screen was on a 4 mile final and there were no aircraft established on takeoff roll or holding in position on Runway 4. I coordinated with the Local Controller to cross Runway 4 at Taxiway 'G'. The Local Controller verbally approved my request to cross Runway 4 at Taxiway 'G.' I instructed Aircraft X to cross Runway 4 at Taxiway 'G' then turn right onto Taxiway 'BB' and hold short of Taxiway 'E.' the pilot read back the taxi instructions and proceeded to cross Runway 4 as instructed. While watching Aircraft X cross the runway I heard the Local Controller issue taxi into position and hold (TIPH) instructions to a departure and then advise the pilot to be ready to 'go right out.' I saw Aircraft Y in position on Runway 4 and a regional jet taxiing into position and hold for Runway 4. I immediately told the Local Controller that I still had a runway crossing in progress at Taxiway 'G.' as soon as I observed Aircraft X complete the runway crossing; I coordinated with the Local Controller that I was 'clear of Runway 4.'I recommend the use of 'memory joggers' for the Local Controller. For example:1. Folding the strip of the aircraft holding in position in the up position.2. The Ground Controller physically placing their hand on the departure bay; in the way of the Local Controller; to prevent reading and/or movement of the strips lined up for departure.3. A 'runway crossing' strip placed in the departure bay until a crossing is complete.


Second narrative: Ground asked for and received a crossing from Local on the departure runway. Ground crossed Aircraft X. Before the crossing was complete Local cleared Aircraft Y for departure. I was trying to work out the location in the line-up for our BOS departure that had an Apreq time and did not notice the error until Ground Control brought it to my attention. At this point it seemed that Aircraft Y had just begun their departure roll and Aircraft X was clearing the runway. Although the Cab Coordinator has many responsibilities I must prioritize better and be more vigilant in my duties.


Synopsis: LGA controllers describe a runway incursion due to the Local Controller forgetting that he/she had approved a runway crossing downfield.