A: PC-PUMP checks the input in the wellbore survey to ensure it meets certain criteria (for example each survey point must be at a deeper measured depth than the previous one). PC-PUMP, however, does not check everything. This error is most likely caused by an incorrect value in the survey. You can probably find the problem by scanning your inputs for a number that looks out of place. If not, save the file and email it to C-FER for diagnosis.