Learjet 35
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 125; Flight Crew Total 24000; Flight Crew Type 12000
Ground Event / Encounter Other / Unknown; Ground Excursion Runway
Air Traffic Control Provided Assistance; Flight Crew Regained Aircraft Control
Weather; Airport
I was flying from ZZZ1 to ZZZ. I got a weather update while refueling in ZZZ1. When we were about 10 mins before landing; I called the Tower and asked about runway conditions. The Tower told me that within the previous 15 mins a landing aircraft reported braking good. The controller reported the runway braking 5-5-5. I touched down on Runway 10 about 300 feet from the approach end. Initial braking was fair to good. About 2/3 of the way down the runway we were below 40 knots; I was applying full braking with some effect. As we approached the end of the runway we were slow enough that I felt I could turn onto the taxiway. The aircraft turned toward the taxiway; but the direction of travel did not change. We slid through a small bank of snow off the end of the pavement and came to rest with the aircraft perpendicular to the runway centerline; nose to the right; with the right main landing gear about 8 feet from the pavement. There was no damage; and no injuries.
I was operating as First Officer from ZZZ1 to ZZZ. The Captain and I reviewed the weather and found it favorable for the flight. Prior to landing; the Captained called the Tower and the Controller reported runway braking condition were 555. I recorded the ATIS prior to landing; it was winds calm; 500 OVC and 10sm visibility. We came in on the ILS RWY 10 and broke out above minimums. We continued the approach and landed between the number and the precision touchdown markers. Halfway down the runway; the Captain informed me that the aircraft was sliding and the airplane started to drift to the left. The Captain corrected to the centerline. The aircraft slowed down to taxi speed and the Captain attempted to turn onto the taxiway. The aircraft did not change direction and slid off the runway. The aircraft came to rest about eight feet off the end of the pavement.
Lear35 flight crew reported a loss of directional control while exiting the runway with reported braking action of 'good'.