Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 240; Flight Crew Total 16000; Flight Crew Type 5000
Human-Machine Interface
ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance
Chart Or Publication; Human Factors; Procedure
The MSCOT arrival is not built so the Airbus--as programmed--can fly the arrival without intervention. The FMGC was loaded by us correctly. There was only a slight headwind. The FMGC plans descent to cross JJACK at 19;600 feet which is 600 feet high. The FMGC plans to cross MSCOT at 250 knots; 30 knots slow. These are I assume programmatic errors with the airbus FMGC; but I thought the intent of these arrivals was to simplify [our task] and make our arrivals more efficient. This and several other arrivals into IAH (I have previously referenced the others in an FSAP); do not achieve this. The workload is increased exponentially as designed. These are violations waiting to happen for crews if they are not well ahead of the FMGC's plan. This needs to be corrected; and in my opinion the company needs to issue a communication to aircrews warning of the possible traps on these arrivals. This is not a professional analysis; but the way these new procedures have been instituted is very frustrating. The method puts crews at jeopardy every day. I asked ATC in the past if they were aware of the limitations and they said they had heard nothing. Incredible.
An experienced Air Carrier Captain advised the crossing restrictions of the MSCOT RNAV STAR to IAH appear to be incompatible with the programming/autoflight capability of the A320; planning to cross JJACK 600 feet high and MSCOT 30K slow. Flight crew intervention required to correct those errors significantly increases flight crew workload; draws their attention away from other critical duties and exposes them to certificate action due to non-compliance.