I believe, when my Grandpa did things for TWA that were other than line duty (Manage pilot training, acceptance flight and develop training for DC-9, manage Saudi Arabian Airlines) he was paid "top line pay" - or what the most senior Captain on the biggest airplane made, plus some other incentives. He only did this in bits - the Saudi thing was two years, the Training center was 2 or 3. After his last non-line position, he went back to flying the line - mostly domestic on the DC-9 because he njoyed the airplane and slept at home most nights. I think the money he made in the non-traditional roles helped him by not giving him the need to continually bid larger equipment in out of town bases (NYC, LA).

As a follow up - any old TWA guys know what the deal with Saudi Arabian Airlines was? Seems like a lot of old mechanics and others did at least some time there.