Re: Maximum operating airport altitude for commercial jets
If there's a market for it, any airliner can probably be certified for ops at LaPaz or Quito etc. There are plenty of restrictions (TOGW, etc.) but it can be done. Additionally most operators will have special procedures - the crew goes on 100% oxygen 30-60 minutes before departure, etc.
This is one area where four donks really make a difference! Having 75% thrust available at 13,000 ft. really beats 50% available.