Date: 201604
Local time of day: 0601-1200
Location: LGA.Airport, NY
Flight conditions: VMC
Light: Daylight
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Tower LGA
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Confusion; Time Pressure
Second reporter function: First Officer; Pilot Not Flying
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Incursion Runway
Detector: Person Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Issued New Clearance
Contributing factors: Chart Or Publication; Procedure; Human Factors
Primary problem: Procedure

Narrative: Taxied out for takeoff on taxiway B to RWY 4. RWY was being used for both takeoff and landing. There were at one time 8 airplanes lined up ahead of us. Weather was clear; VMC. We had just arrived and landed on this runway with a visual approach an hour before. The separation was tight between landing and departing aircraft. One of the airplanes ahead of us took too long to get established in takeoff position and the tower instructed them to clear the runway immediately to the left for landing traffic. We tried to keep close to the airplane in front of us in order to maintain a quick flow. As we approached the number one spot holding short; the tower advised us that we had passed the ILS HOLD SHORT LINE. We were stopped at the runway hold short. A landing aircraft was approaching and the tower instructed us to cross the runway at AA and go the intersection of CY and turn around. As we crossed the runway; the approaching aircraft seeing us on the runway did a go-around. We crossed RWY 4 as instructed and came back and now stopped at the ILS HOLD LINE on AA. Now the tower controller tells us there was no ILS HOLD LINE on AA. We are looking right at it. We are then told to proceed forward. After a few other takeoffs; we are cleared for takeoff from RWY 4 with no further incident or confusion. We notice that now arrivals have been directed to the visual approach to 31.In my flying experience I have not been to an airport where an ILS HOLD LINE was used during VMC conditions. After the event the FO and myself looked again at the airport diagram and at the ATIS. In the ATIS it does mention ILS HOLD LINE in use and on the airport diagram there is a caution with a box. We both missed that and frankly wouldn't have meant much to us under clear skies. There was no mention in the NOTAMS of this special circumstance at LGA and it was not in our Jepp notes. I realize now that it is for wingtip clearance for the landing aircraft. My suggestion would be for the controller to stress stopping at the ILS HOLD LINE. Additionally to mention clearly in the airport notes and on the 10-9 that this is for wingtip clearance and applies under all visibility conditions.


Second narrative: [Report narrative contained no additional information.]


Synopsis: A B737-800 flight crew reported crossing the ILS hold line while waiting for takeoff on Runway 04 at LGA. Crew was confused as conditions were VMC and ILS not in use. Crew later realized the ILS hold line is used for wingtip clearance for landing traffic.