Date: 201912
Local time of day: 1201-1800
Location: PWM.Airport, ME
Flight conditions: IMC
Weather elements / visibility: Icing; Snow
Light: Dusk
Aircraft: Small Transport
Operator: Air Taxi
Operating under: Part 135
Flight plan: IFR
Flight phase: Taxi
Reporter organization: Air Taxi
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Other / Unknown; Distraction; Confusion; Communication Breakdown; Situational Awareness
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown; Ground Excursion Taxiway; Inflight Event / Encounter Weather / Turbulence
Detector: Person Other Person
When detected: Pre-flight
Result: General None Reported / Taken
Contributing factors: Airport; Environment - Non Weather Related; Human Factors; Weather
Primary problem: Weather

Narrative: I was taxiing from the [FBO] hangar to gate; in preparation for boarding of flight to ZZZ. It was the first flight of the day; as all previous flights had been cancelled due to winter weather. Because all airport surfaces were covered in snow and ice; snow removal men and equipment were at work on the taxiways and ramps. After I contacted ground and requested a reposition from the hangar to the terminal; I was assigned an escort operations truck to guide me to the terminal as surface markings were nearly impossible to see being covered in snow; and snow removal equipment were busily plowing surfaces nearby. After following the operations vehicle ahead of me to the terminal on taxiway C we were quite close to terminal. The truck ahead of me was going faster than I felt comfortable keeping up with due to the slippery taxiway conditions; so there was about a 50 yard gap between his truck and my airplane. As we approached the ramp close to gate; I took in the situation going on around me. There were lots of plows; trucks; and snow blowers quickly moving about the ramp. I noticed one plow heading perpendicular to my plane; and moving quite quickly. I instinctively stopped the aircraft; just in case the plow for some reason didn't see me; or his brakes failed; as it was quite slippery on all surfaces. I'm glad I stopped; because the plow kept going right in front of me. I'm not sure if the plow did not see me; or if he just assumed I would yield to him plowing; but the Ground Controller quickly notified the operations escort truck in front of me that the plow had just 'cut me off.'The plow operator didn't respond; and continued plowing normally; leading me to believe he had seen me and just assumed I would stop for him. The plow had just come from the area in front of gate; and plowed a clearing into taxiway C; right in front of me. At this point; my escort truck was over 100 yards ahead of me; and waiting for me to follow its course. However; this course would lead me close to more moving plows and trucks; and I did not feel comfortable proceeding ahead. So I continued remaining stopped. Because there was so much activity straight ahead of me; and none to the right of me; (which is where my gate and final destination are located) I asked the controller if I could make a right turn; and taxi straight to my gate. The Ground Controller asked my escort if this was ok. The escort replied that it was ok. The Ground Controller then instructed me to 'proceed at my own risk' to the gate. I taxiied the aircraft straight to the gate; bypassing taxiway A; and hazardous snow removal equipment and blowing snow from the machines. A cape air ramp agent was awaiting my arrival with lighted wands; and I was able to park the aircraft normally.This morning; a [Company] employee notified me a 'taxiway excursion' report may be filed for what I had done [a few days earlier]. I wasn't sure what he was referring to when he first told me; then I realized that aircraft do not normally taxi between [the] gate and taxiway C. When I taxied the airplane on this course on Tuesday night; I did not realize this. It was very dark out; all ground markings were completely covered over in snow. In addition; there was no visible difference between the taxiway and ramp; as it was all just paved asphalt with a layer of snow on top of it. Because of this; I saw no threat to my aircraft or any other ground equipment; and decided it would be the safest option rather than taxiing on taxiway A; close to fast moving plows and blowers. In doing so; I did not realize I had taxied my aircraft over an area where aircraft are not normally allowed to taxi. This exact area (although not specifically marked on airport diagram) is located between the East End of the terminal apron; and the South End of taxiway C.Loss of positional awareness of taxiway and ramp during winter weather conditions; and approval from air traffic control to proceed at my own risk through an area not normally authorized for taxiing aircraft.Not being allowed permission to taxi through an area not normally authorized for taxiing. Lights illuminating an area not authorized for aircraft taxiing. Designated marking on airport diagram saying there is a no-taxi zone between taxiway C and terminal apron.




Synopsis: Pilot reported a snow plow cutting off aircraft while taxiing to gate.