Medium Transport
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Aircraft; Human Factors
Cleared by ATC from RSW via CSHEL5 ORL as filed. Briefed the departure at the gate before push back and verified the departure setup.Upon reaching runway 6; we completed the before takeoff checklist. Cleared for takeoff by tower - runway heading runway 6. Departing runway 6 from RSW; CSHEL fix is dropped from the legs page. Departure control cleared us direct CSHEL; however the fix dropped out of the legs page in the FMS. We advised ATC and they assigned a heading of 360deg to give us time to re-input the CSHEL fix. We confirmed the routing on the 20-3A RNAV SID and flew direct to CSHEL. Flight continued without incident.Future crews must be aware of this when departing runway 6 at RSW that CSHEL will drop out of the legs page. We flew this same departure yesterday departing runway 24 without incident. All of the fixes remain in when departing runway 24.
Captain reported that after departing Runway 6 in RSW the FMC dropped the CSHEL fix.