B737NG flight crew reported a runway incursion at 31R in mdw.

Attributes
ACN	1327384
Time
Date	201601
Local Time Of Day	1201-1800
Place
Locale Reference	MDW.Airport
State Reference	IL
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737 Next Generation Undifferentiated
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 125
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 260
Events
Anomaly	Conflict Ground Conflict Less Severe Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Ground Incursion Runway

Narrative:

We were cleared to taxi to runway 31C at mdw via P; G. While on taxiway G; there was a company aircraft holding short of 31C on taxi line E1. With E2 and E3 taxi lanes open; I taxied behind the E1 aircraft and held short of 31C on taxi line E3. Almost clear of the E1 holding aircraft's tail; mdw ground control called and said I should not have passed behind the aircraft. After stopping at the hold short; mdw tower cleared a smaller business aircraft to change from 31C and cleared him to land on 31R. Even though there was no aircraft inbound to 31R when I taxied around/behind the aircraft at the 31C hold short; I think I crossed the hold short line for 31R with my left gear. I still think taxiway G ends and dumps into the huge apron of E1; E2; and E3 hold lines for 31C. I have done this many times; and never been called by ground control. I have often been holding short for 31C on E3 and/or E2 and had aircraft be cleared to land 'over' me on 31R. This is why I did not consider my movement around the holding aircraft to be an encroachment of another runway.

Original NASA ASRS Text

Title: B737NG flight crew reported a runway incursion at 31R in MDW.

Narrative: We were cleared to taxi to Runway 31C at MDW via P; G. While on Taxiway G; there was a Company aircraft holding short of 31C on taxi line E1. With E2 and E3 taxi lanes open; I taxied behind the E1 aircraft and held short of 31C on taxi line E3. Almost clear of the E1 holding aircraft's tail; MDW Ground Control called and said I should not have passed behind the aircraft. After stopping at the hold short; MDW Tower cleared a smaller business aircraft to change from 31C and cleared him to land on 31R. Even though there was no aircraft inbound to 31R when I taxied around/behind the aircraft at the 31C hold short; I think I crossed the hold short line for 31R with my left gear. I still think Taxiway G ends and dumps into the huge apron of E1; E2; and E3 hold lines for 31C. I have done this many times; and never been called by Ground Control. I have often been holding short for 31C on E3 and/or E2 and had aircraft be cleared to land 'over' me on 31R. This is why I did not consider my movement around the holding aircraft to be an encroachment of another runway.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.