A320
Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Situational Awareness; Human-Machine Interface; Distraction; Confusion; Workload
Aircraft Equipment Problem Critical; Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Aircraft; Chart Or Publication; Human Factors; Procedure
We were taken off the GEELA RNAV STAR; MOHAK transition; given numerous heading and airspeed clearances and then cleared direct GEELA and cleared to 'descend via' the arrival. We verified and executed the clearance; then selected Managed Descent.At this point we transitioned FL180 and I called for the descent Approach Checklist. Upon reaching MNSTR I noticed that we were at 13;000 although the procedure required crossing between 16;000 FT and 15;000 FT and at 250 KIAS. I advised the Captain; verified the situation; ensured we were in Managed Descent and complied with all remaining restrictions.I'm not sure what happened! I just do not know how much more I can do. ATC is always issuing new clearances and restrictions which create a lot of confusion when running checklists and managing the vertical path and ensuring compliance with restrictions. We get way too many clearance modifications from ATC on all of the arrivals; all of the time and on a regular basis.
An A320 flight crew; as well as the Managed Descent mode of the FMGC; were flummoxed by multiple ATC directed modifications to the GEELA RNAV STAR and descended to cross MNSTR at 13;000 vice between 16;000 and 15;000 as required. The reporter expressed his dismay for the complexity of the STAR procedure; the inability of his autoflight system to comply with that complexity and especially for modifications to it given by ATC which may render the flight crew unable to comply due to excessive workload.