Medium Large Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 87; Flight Crew Total 2901; Flight Crew Type 101
Situational Awareness; Troubleshooting
Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Runway
General Evacuated
Human Factors; Airport; Weather
We were repositioning empty to pick up our passenger. We planned on departing at XA00; so we arrived at the hangar [an hour and a half early]. After filing for an XA00 departure; I didn't see any NOTAMs at RIL regarding braking action; so I called FBO in KRIL to see if they'd had any reports. They told me that braking action was reported 'medium.' I reviewed our performance charts in our quick reference handbook for a contaminated runway with ice and we were within the unfactored distance. I briefed the other crew member; and we decided to make sure we land right in the touchdown zone and put the nose down first before we started using thrust reversers in case of an asymmetric thrust reverser deployment. We were delayed past XA00; but were able to depart just after XB00.We were cleared for the ILS 26 into RIL with traffic 15-20 miles in trail. The ASOS was reporting 'unknown precipitation' and -2 degrees Celsius. On the approach we again reiterated that if we did not land in the touchdown zone; we would perform a go around. We broke out of the clouds approximately 5 miles before the runway. We landed exactly as briefed; and when I checked the braking action; it was good at approximately 1200 feet down the runway. I decelerated to approximately 50 knots; and checked again at the halfway point of the runway and decelerated further to approximately 20 knots. The traffic on the ILS behind us asked what the braking action was; and we reported 'Good.' My co-captain said to 'not try to make this one' referring to not trying to stop by taxiway A2 in order to prevent higher braking than required. I complied and we continued to roll to the end.At approximately 1000 FT to the end of runway 26 and at approximately 15 knots; I again applied brakes. Nothing happened. I immediately scheduled thrust reverser deployment. As soon as I did that; the other crew member said 'slow down.' I replied 'I can't.' We watched as we slowly slid straight off the runway; into the overrun; and out about 20 feet into the grass. We notified Denver Center about the overrun; and they closed the runway. We shut down the engines; called for the airport authority to come meet us; opened the door; and inspected the plane. We found zero damage. Airport Fire and Rescue drove out onto the runway to come meet us. When they reached us; they also reported that they could barely stop their trucks. We spoke with them and decided to attempt to taxi off the grass; back onto the runway via our own power. We put our gear pins in and were able to successfully taxi back onto the runway. After we parked the aircraft on the ramp; we did another visual inspection. We again found no damage. My other crew member did an extensive visual inspection of the landing gear and belly antennas. He determined a third time that no damage occurred to the aircraft. He spoke with a representative of the NTSB and they took a report from him. We spoke with our Chief Pilot; our Safety Management System Coordinator; and the President of our company. They all determined that since no damage was done; they thought it was safe to continue operations. I learned a few very important lessons: brake while you can. The braking action was good for the first 2/3 of the runway. I thought it was best not to be aggressive on the brakes to avoid skidding at high speeds. Once I determined the braking action was good; I should have continued to decelerate quickly. I also learned that weather is so volatile in the Rocky Mountains; that I should have called to get a braking action report again before I departed. I was caught up getting the plane ready that I didn't think to call KRIL again to get an updated report. The fact that KRIL is uncontrolled also played a part as well. The ASOS reported a special observation with light freezing rain just 6 minutes before we landed; but we never received that report because we had already received the ASOS prior to it being updated. If the field had a control tower; it would have been broadcast over the communications frequency that weather had changed. In the end; no damage or injuries resulted but the fact that it happened at all is a serious matter that I will never forget. I will definitely make changes to how I operate in the Rocky Mountains with volatile weather.
Corporate turbojet ran off the end of a runway into the overrun due to nil braking action at the end of the runway. No damage inflicted to the aircraft.