Anyone who states that "there is no problem" doesn't understand the nature of the situation. It
does need to be carefully considered, and not simply from the CRM point of view.
- If in the company concerned, the right-seater is regularly and frequently in that seat, then there is less of a problem. But simply taking someone from the left-seat, putting them in the right, doing a quick check on them and letting them go is not enough. I am double-seat qualified in a few aircraft and I REALLY have to think about where the hands are going to operate this, that or the other.
- The worst FO's I ever flew with were Training Captains. The extent of the duties of an FO are different in every company, and I have met several TC's who couldn't even get the weather off the computer.
- CRM - not an insuperable problem if everyone on the flightdeck operates professionally and with regard to good CRM, but we know that isn't always the case. Some Captains become overbearing in the right seat, particularly if they are senior to the Captain in the left. Others shut up to too great an extent, not wanting to be seen as nit-picking.
In one of my previous companies we had a small spate of runway incursions - four in six weeks. On examination, in every case there were two captains on the flight deck.
Unless in the company concerned it is a frequent occurrence and people are truly double-seated and used to operate as often in the right as the left seats, two captains together is the most dangerous combination of crew possible.