Date: 201703
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: Citation X (C750)
Operator: Fractional
Operating under: Part 135
Mission: Passenger
Flight phase: Landing
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Pressurization System
Component problem: Malfunctioning
Reporter organization: Fractional
Reporter function: Pilot Flying
Human factors: Situational Awareness; Workload; Confusion; Distraction; Troubleshooting
Second reporter function: Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe; Airspace Violation All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural FAR
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Became Reoriented
Contributing factors: Airport; Human Factors
Primary problem: Human Factors

Narrative: The PIC takes full responsibility for this event. This was an embarrassment to [Our Company] and to the pilots involved. The crew did their descent checks briefing which included tuning up the NDB and both sides had their respective NDB needle up. They even made a 'Place Bearing Distance' (PBD) fix at 5miles at 3'500 feet at the end of the runway. On the descent into ZZZ1; descending through approximately 38;000 feet the amber Cabin Altitude CAS message came on and so both pilots DON their mask. The cabin altitude was steady at approximately 8;500 feet and the crew stated to ATC that they wanted to keep descending due to a pressurization issue. ATC asked the pilots if they wanted to declare an emergency and they declined since the cabin was stabilized at 8;500 feet. The pilots were then given a different fix to fly to. They were filed to ZZZ but were given direct ZZZ VOR direct ZZZ1 plus they were also given a crossing restriction. Which I believe was to cross 15miles west of ZZZ1 at or below 14000 cleared to 9000. The nonflying pilot was busy reading the checklist and flying pilot was flying the aircraft and on the radio. The amber Cabin Altitude message went out as they descend through 25;000 feet. ATC told them the airport was at their 11 o'clock and so they had an airport in sight. The wind was reporting at ZZZ1 230/13G16KTS. The wind vector display on the FMS showed a steady cross wind of 18kts while on final and so flying pilot had his hands full. The flying pilot saw the runway numbers 30 and landed the aircraft safely. Once they taxied clear of the runway the pilots had difficulty reaching the FBO. That's when they realized that they landed at the wrong airport and landed at ZZZ2. The PIC informed the passengers of the mistake and they decided to reroute their transportation. It was a combination of multiple factors that lead to this mistake: Maintenance issue (cabin altitude CAS message); multiple ATC instructions while running through an abnormal checklist; 2 airports near each other lined up in the same magnetic direction; large inviting runway in the same general location where ATC says it's located; and a strong crosswind that needed visual cues to land the aircraft safely. Task saturation was a large culprit to this error and again; the PIC takes full responsibility for this event. This never should have happened nor will it again. The pilots should have declared emergency and they would have received preferential treatment. They should have encompassed geographical clues about the airport ZZZ1 during the briefing. The flying pilot should have used his instrumental cues to align himself up to the correct runway/airport.


Second narrative: Second in Command (SIC) occupied the left seat for training purposes. Pre-departure briefing included the fact that ZZZ1 was an uncontrolled airport and a review of relevant landing procedures. For situational awareness ZZZ1 NDB tuned and displayed and a point; bearing; distance 5nm from at 3;500' established in the FMS.A routine departure and cruise at FL430 ensued. Descent commenced to cleared FL370. At approximately FL380; an EICAS 'CABIN ALTITUDE' annunciated. Cabin altitude of approximately 8;500' was observed. Oxygen masks were donned and communications established. ATC advised of a pressurization issue and the need for further descent. Descent was expedited. Descending through approximately FL250 the cabin altitude stabilized then started to descend.Both the PIC and myself saw what we believed to be the ZZZ1 airport at our 11 o'clock position and so advised ATC. ATC cleared our flight for a visual approach which was accepted. The flight maneuvered on a left down wind and aligned with a clearly marked runway and landed on that runway. This however turned out to be runway at the ZZZ2 airport.Accept the pressurization issue as an emergency and so advise a ATC. Be aware of geographical features unique to the intended airport e.g. ZZZ1 has crossing runways. ZZZ2 does not. Do not abandon valid NDB indications. Utilize the place bearing distance que that was established. Be aware of task overload to the detriment of an accurate landing.


Synopsis: Citation 750 flight crew reported a pressurization malfunction and requested priority handling from ATC to their destination airport. While dealing with the malfunction they accidently landed at the wrong airport.