Date: 201704
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Night
Aircraft: Beechjet 400
Operating under: Part 135
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: FMS/FMC
Component problem: Improperly Operated
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Training / Qualification; Human-Machine Interface; Confusion
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew FLC Overrode Automation
Contributing factors: Human Factors; Staffing; Company Policy
Primary problem: Human Factors

Narrative: We had an avionics issue which almost caused an altitude deviation. We were assigned and told to descend via the arrival. The arrival was entered into the FMS and double checked. The arrival was flown on autopilot in VNAV mode with auto throttles on. We noted that the FMS altitude at ZZZZZ intersection was correct; 4000; but was noted in yellow; not in magenta as all other altitudes were. This normally indicates that the FMS has noted an issue; which we believed was caused by the ILS Runway XXC being loaded with an altitude of 5000 at ZZZZZ1 intersection. Normally the FMS/VNAV will still drive the aircraft to a YELLOW altitude but alert the crew that the altitude is in conflict with another altitude. The aircraft leveled at 6000 at ZZZZZ2 intersection as it should have; the FMS calculated a top of descent for 4000 but then leveled at 5000. We quickly disconnected the autopilot and manually descended to 4000; which I believe was completed by ZZZZZ intersection. The flight director and FMS still were showing 5000 even though the altitude selector was set to 4000 at the beginning of the VNAV descent over ZZZZZ3 intersection. I don't believe any altitudes were busted nor did ATC make any note of our progress. This is another example of the issues of flying 3 different aircraft; with 3 very different avionics; 3 different engines; 3 different checklists; 3 different QRH books; 3 different flows and SOPs; and 3 different sets of limitations. It has been over 2 years since we acquired another aircraft type at [Company]; we have not implemented safety considerations for the crews who are required to fly all 3 aircraft. In fact the company has applied pressure to the crews who have expressed safety concerns regarding their ability to safety fly all 3 aircraft. I have been told that I must fly all three aircraft regardless of my safety concerns. Only one member of management has supported my concerns and stated that I can deny flights in any aircraft that I feel uncomfortable in. However this puts pressure on the crews. Safety is created by good policies and by removing pressure; not applying it. I know many other [aircraft type] crew members are concerned that [Company] is not taking this safety issue seriously and dealing with the situation in a timely manner. 2 years is not timely; nor should known legitimate safety issues take a back seat to staffing issues.




Synopsis: Beechjet Captain reported disconnecting the autopilot on descent when it leveled above the cleared altitude; and expressed frustration with flying different aircraft with different engines; checklists; QRH books; flows; SOPs; and limitations.