Beechjet 400
Flight Crew Air Transport Pilot (ATP)
Workload; Training / Qualification; Distraction; Time Pressure
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Diverted; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Aircraft
Shortly prior to initiating our initial descent the First Officer (FO) Pilot Monitoring (PM) noted that our hydraulic pressure was indicating very close to the red line 1750-1800 (red line was 1850). I noted and recorded the pressure on the gauge. I then requested him to run the appropriate checklist for high Hydraulic Pressure. After completing the abnormal checklist; we came to a consensus on our best alternate option and then requested a diversion to utilize the longer runway and have emergency equipment available to us. We briefed our arrival.  The passengers were asked to come up to the cockpit where I briefed them on a possible emergency landing; the plan of action and the hand signals from the crew that would be used to note time to touchdown. We [assumed] the worst case scenario; if we had to land without hydraulics. The abnormal checklist allowed us to utilize the hydraulic pressure when required; and we were able to utilize the hydraulics until completion of the flight.
Before descent I Pilot Monitoring (Pilot Monitoring) noticed hydraulic pressure was around 1800 PSI. Pilot flying told me to run the checklist for it and completed as so. We both figured it'd be best to find a long runway and deviate there. So; we agreed to [the alternate]. After we had the checklist run; the Captain briefed the passengers of the situation and updated any time we could. Meanwhile; as an emergency aircraft; we weren't sure if there would be any other complications so we requested runway XY. [Runway XY] is a long runway well over the the extra we would need had all hydraulics been available. Hydraulics were available per the checklist.
A Hawker 400 flight crew reported abnormally high pressure in the aircraft's hydraulic system. Pilots successfully diverted to a suitable airport.