Now my REAL question. How easy is it to "execute" alternate Flight Plan B by accident? A slip, a slide, a push-pull? By definition, an emergency back-up flight plan should be quick and easy to execute, was it too easy?
This other flight plan in the FMS is normally called the secondary flight plan. Just like disabling ACARS, it can be selected, then activated by a fairly simple keystroke sequence on the CDU (the box with the keys and buttons on it).
Since you have to select the secondary flight plan and then activate it, I can't think of a time when I've seen it done accidentally (or on purpose, for that matter) in the aircraft. I have practiced using the secondary flight plan in the sim on occasion.
Some folks use the secondary flight plan to plot things like ETP's and other stuff over water. I'm a minimalist, the less buttons I push, the less chance of screwing it up is my thinking. We still do legacy plotting and position tracking paperwork. However, in a modern jet I'd rather mess up the paperwork and get it right in the FMS than the other way around.
The primary and secondary flight plans are normally erased automatically after a flight. Some, but not all, carriers also have canned flight plans stored for frequently flown routings that can be called up on preflight into the primary and secondary FMS flight plans.
Over the planned route of MH370, I don't see a reason for route 2 to be different to route 1 in the cruise phase. I also would find it highly unlikely that route 2 could be inadvertently selected AND executed. If it was, and a turn to the left suddenly ensued, why not just re-activate route 1?
Yep, I agree.