Air carrier Captain reported the similar fix names; NOONN/NOONE; led to a navigation error.

Date: 2026-01 · Aircraft: Commercial Fixed Wing · Phase: cruise

Anomalies: aircraft-equipment-problem-less-severe|deviation-track-heading-all-types|deviation-discrepancy-procedural-clearance|deviation-discrepancy-procedural-published-material-policy

Synopsis

Air carrier Captain reported the similar fix names; NOONN/NOONE; led to a navigation error.

Narrative

Normal flight XNA - ZZZ. Followed FOM/AOM procedures. I was Captain and PM and the FO was PF. During preflight I programmed Perf-Init (Performance Initialization) and FO input the route into the FMS. During route verification I read it off and FO checked each point. However; a GPS point was misspelled in the FMS. We were cleared to navigate to NOONN intersection on the departure clearance. However; the point in the FMS was spelled NOONE; which is about 50 NM south of NOONN. Neither of us saw the misspelling and we continued the flight. It wasn't until we crossed BETIE and the aircraft turned toward NOONE instead of NOONN when ATC inquired what fix we were navigating toward. They issued a new clearance to fly direct COMDY. They didn't issue a pilot deviation and the flight continued to ZZZ.The cause was the Captain's failure to catch the misspelled GPS fix. A contributing cause to this was the FO's failure to spell the correct fix into the FMS.The pilot reading off the FMS for the route verification should also verify the route spelling on their EFB or the PDC to check for spelling errors.

Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.