A320
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Fatigue
Aircraft Equipment Problem Less Severe; Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Aircraft; Human Factors
On the Delta 4 arrival into SLC was cleared to cross JAMMN at 17000. Had verified altitude restrictions with the pilot flying. Approaching the fix was cleared to descend via. PF selected 11000 for lowest restriction at MAGNE. We were still in managed descent. Prior to SPIEK we both verified altitude and noticed we were low. The aircraft had reverted to vertical speed. Started the correction and advised ATC asking for a safe altitude. Was given 13000. We had visual on terrain and no TCAS warning. Was then cleared to maintain 11000 and given a runway assignment of 16L. Continued on downwind and cleared for a visual. The flight started with a three hour round trip. We had a mechanical upon return and changed planes. Had to wait for a security check on the plane prior to boarding. Then 2 mechanical issues. No catering bins; had to wait on that. Late push. Late arriving into SLC. I feel fatigue was the main factor in catching the event immediately. The aircraft losing automation was the ultimate cause of the event but was preventable had we been more alert.
Vertical Speed being activated at some point without us being aware of the change from Managed Descent. High task loading at this phase of flight. Distraction with the FA announcement procedures as the PF and approach chart verification.
A320 flight crew reported missing a crossing restriction at SPIEK on the DELTA 4 Arrival SLC. The FMGC had reverted to vertical speed with 11000 feet set. The flight crew detected the error just before ATC issued a low altitude alert. Fatigue was cited as a contributing factor.