Narrative:

We landed at mdw with an inoperative (left) pilot side windshield heat. The alternate windshield heat system either was not working properly; or simply did not provide enough bleed air to heat the windshield adequately to prevent 'fog' from forming. Although; I (the flying pilot) had enough visibility to safely land the airplane; it quickly became clear that I would not be able to taxi the airplane to the ramp. My co-pilot's electrically heated windshield was working properly so he was able to take the aircraft and begin to taxi. As fate would have it; it seemed all of our turns during our taxi were made to the left; which required my co-pilot to have at least some visibility out of my side of the windshield; which by now; was all but impossible. All I could see was the glow of the lights; and could not distinguish taxiways from grass. Upon clearing the runway; the ground controller did not issue us a specific taxi route which allowed us to essentially find our own way to the ramp. I thought it was a bit unusual that he did not issue us a specific route considering the maze of taxiways and runways at mdw; but there was; after my initial look at the airport diagram; an obvious route that would take us to the FBO that would not cross the active runway. We cleared runway 31C at the end; and made a left turn onto taxiway west and continued on west until we approached runway 4L. As we got closer to the runway intersection; I consulted the airport diagram; and noticed after crossing 4L we would have to make a decision as to which taxiway to take to cross 4R. I was not going to make that decision without consulting the tower and they said to cross 4L onto V; turn into the holding pad; join Z; then cross 4R; and join Y to the ramp. At some point; due to our ever-worsening visibility; we did not join Z prior to crossing runway 4R; and instead; remained on taxiway V which led to nowhere but runway 4R. We had to make an immediate decision to turn right onto the runway and clear at the end onto taxiway Y. The ground controller did not say anything about our mistake; and the runway was not active; however; it was clearly a mistake on our part which I take full responsibility for. There were multiple factors that contributed to this situation; and several of them were things that I definitely should have done differently. Obviously the root of our problem was the inoperative windshield heat. The system has been inoperative for several weeks and is MEL'd. I have been in communication with my chief pilot and director of maintenance since this incident happened and am in the process of trying to convince them that we need to either move up the repair date or possibly consider not dispatching this aircraft at night. This part of the event was clearly out of my control. The part of the situation that was in my control and I should have handled better; was when we were not immediately issued a specific taxi route; I should have demanded one. As I stated earlier; mdw has a maze of taxiways and intersecting runways that are difficult to navigate under the best of circumstances. I waited too long to get an assigned route and by the time I received it; our visibility situation had deteriorated and we were more focused on keeping the plane out of the grass than we were on navigating properly. In hindsight; what I probably should have done after crossing runway 4L was go into the holding area; shut down; and gotten a tug; but by that point we could see our FBO and 'get-there-itis' had set in. As I write this and consult the taxiway diagram; I am rather surprised that the holding area between runways 4L and 4R is not a 'hotspot.' with the confluence of 4 or 5 taxiways all coming together between two closely spaced runways; it seems like an area that should be closely watched. Perhaps if it was designated as a 'hotspot' the controller would have immediately given us a specific taxi route instead of waiting until I requested one. I'm not 100% sure of this; but aren't controllers required to give specific taxi instructions regardless of the situation? I thought that requirement had been implemented several years ago.

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Original NASA ASRS Text

Title: Air Taxi Captain landed at MDW with the left windshield heat on MEL which had been the case for several weeks. Fog formation quickly required the First Officer to preform taxi duties and a taxiway incursion occured while attempting to cross Runways 4L and 4R to Taxiway Y.

Narrative: We landed at MDW with an inoperative (left) pilot side windshield heat. The alternate windshield heat system either was not working properly; or simply did not provide enough bleed air to heat the windshield adequately to prevent 'fog' from forming. Although; I (the flying pilot) had enough visibility to safely land the airplane; it quickly became clear that I would not be able to taxi the airplane to the ramp. My Co-pilot's electrically heated windshield was working properly so he was able to take the aircraft and begin to taxi. As fate would have it; it seemed all of our turns during our taxi were made to the left; which required my Co-pilot to have at least some visibility out of my side of the windshield; which by now; was all but impossible. All I could see was the glow of the lights; and could not distinguish taxiways from grass. Upon clearing the runway; the Ground Controller did not issue us a specific taxi route which allowed us to essentially find our own way to the ramp. I thought it was a bit unusual that he did not issue us a specific route considering the maze of taxiways and runways at MDW; but there was; after my initial look at the airport diagram; an obvious route that would take us to the FBO that would not cross the active runway. We cleared Runway 31C at the end; and made a left turn onto Taxiway W and continued on W until we approached Runway 4L. As we got closer to the runway intersection; I consulted the airport diagram; and noticed after crossing 4L we would have to make a decision as to which taxiway to take to cross 4R. I was not going to make that decision without consulting the Tower and they said to cross 4L onto V; turn into the holding pad; join Z; then cross 4R; and join Y to the ramp. At some point; due to our ever-worsening visibility; we did not join Z prior to crossing Runway 4R; and instead; remained on taxiway V which led to nowhere but Runway 4R. We had to make an immediate decision to turn right onto the runway and clear at the end onto Taxiway Y. The Ground Controller did not say anything about our mistake; and the runway was not active; however; it was clearly a mistake on our part which I take full responsibility for. There were multiple factors that contributed to this situation; and several of them were things that I definitely should have done differently. Obviously the root of our problem was the inoperative windshield heat. The system has been inoperative for several weeks and is MEL'd. I have been in communication with my Chief Pilot and Director of Maintenance since this incident happened and am in the process of trying to convince them that we need to either move up the repair date or possibly consider not dispatching this aircraft at night. This part of the event was clearly out of my control. The part of the situation that was in my control and I should have handled better; was when we were not immediately issued a specific taxi route; I should have demanded one. As I stated earlier; MDW has a maze of taxiways and intersecting runways that are difficult to navigate under the best of circumstances. I waited too long to get an assigned route and by the time I received it; our visibility situation had deteriorated and we were more focused on keeping the plane out of the grass than we were on navigating properly. In hindsight; what I probably should have done after crossing Runway 4L was go into the holding area; shut down; and gotten a tug; but by that point we could see our FBO and 'get-there-itis' had set in. As I write this and consult the taxiway diagram; I am rather surprised that the holding area between Runways 4L and 4R is not a 'hotspot.' With the confluence of 4 or 5 taxiways all coming together between two closely spaced runways; it seems like an area that should be closely watched. Perhaps if it was designated as a 'hotspot' the Controller would have immediately given us a specific taxi route instead of waiting until I requested one. I'm not 100% sure of this; but aren't controllers required to give specific taxi instructions regardless of the situation? I thought that requirement had been implemented several years ago.

Data retrieved from NASA's ASRS site as of April 2012 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.