Narrative:

At 39;000 feet MSL just prior to planned decent into ZZZ we were approximately 50 nm west of ZZZ1 AFB. We experienced a main hydraulic failure. Among other things; we lost normal braking; airbrakes; nosewheel steering; and normal gear extension capabilities. We were left with emergency braking which is much less effective than normal braking. Our checklist dictated that we needed to plan for a 7;900' landing roll. Our destination only had a 9;300' runway. Considering that we would land approximately 1;000' down and most likely the runway would be wet (based on experience) I did not feel comfortable with a planned landing roll so close to the last brick of the runway when we have longer runways in the area. To complicate the problem the weather at ZZZ was forecast to be broken at 900; overcast 1500; 3 miles vis with fog. ZZZ1 had ATIS information left; at the time; we were making our divert decision with overcast at 1700' and 10 miles visibility. Considering the potential stopping problem and the directional control problem we faced we needed to find a large runway with good emergency services. We discussed what was the longest and widest runway within the radius to which we could fly. We determined ZZZ1 was the best option based on the fact that the runway is 12;000' long and 300' wide and the weather was the best for the area. I called ZZZ1 ground as there was no VHF tower frequency published on the government charts. They said they were open and could handle us as an emergency landing. Thus; we diverted into ZZZ1 and shot the ILS to runway xx down to minimums (200 and a 1/2 with heavy rain) contrary to what ATIS called the weather. The major event of this is that we diverted a civilian aircraft to a military field.

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Original NASA ASRS Text

Title: G100 Captain experiences main hydraulic system failure at FL390 and elects to divert to a nearby AFB due to the weather and length of runway at destination. Landing is uneventful but weather is much worse than reported on ATIS.

Narrative: At 39;000 feet MSL just prior to planned decent into ZZZ we were approximately 50 nm west of ZZZ1 AFB. We experienced a main hydraulic failure. Among other things; we lost normal braking; airbrakes; nosewheel steering; and normal gear extension capabilities. We were left with emergency braking which is much less effective than normal braking. Our checklist dictated that we needed to plan for a 7;900' landing roll. Our destination only had a 9;300' runway. Considering that we would land approximately 1;000' down and most likely the runway would be wet (based on experience) I did not feel comfortable with a planned landing roll so close to the last brick of the runway when we have longer runways in the area. To complicate the problem the weather at ZZZ was forecast to be broken at 900; overcast 1500; 3 miles vis with fog. ZZZ1 had ATIS information L; at the time; we were making our divert decision with overcast at 1700' and 10 miles visibility. Considering the potential stopping problem and the directional control problem we faced we needed to find a large runway with good emergency services. We discussed what was the longest and widest runway within the radius to which we could fly. We determined ZZZ1 was the best option based on the fact that the runway is 12;000' long and 300' wide and the weather was the best for the area. I called ZZZ1 ground as there was no VHF tower frequency published on the government charts. They said they were open and could handle us as an emergency landing. Thus; we diverted into ZZZ1 and shot the ILS to RWY XX down to minimums (200 and a 1/2 with heavy rain) contrary to what ATIS called the weather. The major event of this is that we diverted a civilian aircraft to a military field.

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.