it has a nominal range of 5010 NM, I've scheduled it on an route of just 2842 NM, and yet I get this message "McDonnell Douglas DC-10-30: Limited to 53 pax by payload/range" why would this be the case?
Runway Requirement. ABZ has a short runway and DC-10 @ MTOW requires more length. Other widebody aircraft can operate at ABZ, just make sure the runway requirement fits the bill. Also note that the inbound (return) legs don't suffer the capacity hit.
As a furtherance, you may fly the DC-10 on this route, however you will need to create a tech stop on the outbound leg that is a short sector length. Example would be Cork, Ireland. Then the penalty goes away!