Beechjet 400
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Confusion; Time Pressure; Situational Awareness
Aircraft Equipment Problem Critical
Flight Crew Diverted; Flight Crew FLC Overrode Automation; Flight Crew Landed in Emergency Condition
Aircraft
At 30 min cruise flight @ FL400; Captain (PF) noticed LT Side PFD (Primary Flight Display) IAS flag; and verbalized to PNF (Pilot Not Flying). PF (Pilot Flying) compared PFDs and STBY ASI (Airspeed Indicator). RT Side PFD and STBY ASIs indicated approximately 20 kts faster (220 kts) than LT Side. Over the course of 30 sec; airspeed continued to decay below 200 kts on LT Side PFD and decreased at same rate on both RT side PFD and STBY. PF deemed a descent necessary to trade altitude for airspeed. PNF asked ATC for lower altitude. PF initiated a ~3000 fpm descent and airspeed continued to decay toward 140 kts on all ASIs. PF quickly realized all airspeed information was erroneous and suspected stuck pitot. Both pilots verified pitot heats-on and circuit breakers-in. PF decreased descent to 1000 fpm; set a known power setting and referenced AOA .2. IAS pegged at 40 kts on both PFDs and 0 kts on STBY. PNF [requested priority handling] and asked for vectors to ZZZ. PNF ran loss of airspeed indication checklist and reviewed loss of airspeed approach checklist. All ASIs returned to normal @ ~FL260 and indicated similar airspeeds. PF flew ILS uneventfully into ZZZ.
Captain reported foreign debris in pitot-static line. Aircraft was near maintenance cycle for system to be blownout.
BE-400 Captain reported loss of air speed indication at FL400 during cruise.