Originally Posted by
BlueZebra
Example: UA 900 (probably a CRJ 700) goes SAN-SFO, arriving around noon. UA 900(heavy) flys SFO-FRA, departing around 2pm, but is a 747. No issue.
Not a good example. A CR7 flight is always operated by UA Express. Two problems here. First, any UAX flight is a four digit flight number. Secondly, the only non-US destination this would be able to continue onto (either in the same aircraft or a different one) would be one in Canada.