Commercial Fixed Wing
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 50; Flight Crew Type 10000
Workload
ATC Issue All Types
Air Traffic Control Issued New Clearance
Environment - Non Weather Related; Human Factors; Procedure; Company Policy
Chicago Approach was very; very busy our entire time on frequency. Runway 13C Ops likely made this more challenging. Some aircraft were given to expect the RNP Y; while some were being vectored to ILS final. We were set up for the ILS as expected but also reviewed the RNP. Approach Control suddenly assigned us direct TINLY to fly the full RNP procedure. I refused as we were only a mile or so away and not prepared (I wonder if that was even legal under their rules?). I could see the First officer (F/O) instantly go heads down and start the FMC re-programming. I have been in this situation too many times before when we try so hard to comply that we rush beyond our capabilities and likely make critical mistakes. Ironically I was showing the F/O earlier how to not succumb to the double discontinuity trap with changing approaches so close in. ATC was a bit miffed and that was disappointing to see as there was no way we could have pulled this off. We then were given vectors to final and landed uneventfully all the while staying in the Green. Chicago Approach has some of the most talented Controllers; but they were trying too hard this day with too much traffic. They were in the Red whether they realized it or not.
Air carrier Captain reported refusing a last-minute clearance change to the RNP approach at MDW; citing workload and the high possibility of programming errors.