B737-700
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Fatigue
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Flight Crew Became Reoriented
Human Factors
During the ILS to 26L; for whatever reason I reset the Alt Select prior to capturing the glideslope and began following a false slope below the FAF. The Captain quickly caught my mistake and I disconnected the autopilot; leveled off and re-intercepted the proper glide path. I didn't realize how tired I was on this red eye until I made such a mistake. Although we had visual contact with airport at all times it was still a breach of procedure. We landed without incident. I followed the fatigue mitigation procedures including caffeine 30 minutes prior to landing but fatigue played a key role in my mistake.
B737-700 First Officer reports selecting a lower altitude on the MCP prior to the FAF and glideslope intercept resulting in descent below the glidepath. The Captain takes note and the reporter takes corrective action. Fatigue was cited as the main factor involved.