Call the airline to apply for the wheelchair service. It is free for NW but
prepare some tips. The service men don't speak Chinese, they work for the
airport not the airlines. They will greet the seniors at the gate. Then they
will send the seniors to the gate for the next flight (just ask your parents
to show them the boarding pass for the next flight). Yes they did wheel my
parents to pass the customs.
They are really helpful especially if your parents can't speak English or
worry to be lost
