This thread keeps running away when I'm not at the keyboard, so I'm late here, but I'd like to weigh in. The issue here, to me, isn't that the player asks for an F-14, but rather how the GM decides to operate on that. It is literal? Is the GM forced to only consider the request as a literal ask for a literal F-14 (metaphorically within the fiction of the game, of course)? I contend no. The ask is based on the reference frame of the player, and, like many asks, needs to be translated into the game.
It feels like you're questioning what much younger me and my character were thinking and wanting. I wanted an F-14, and was thinking one like in the photographs I had seen. And who wouldn't want rockets and radar in a world of carts and horses!
So, then, what's the difference? Magnitude. Asking for an F-14 is a pretty big departure from the game fiction so it confounds our normal translation because of this and because we haven't trained ourselves in translating F-14s the way we have the more common statements. So, we evaluate it not in need of translation into the fiction, but as something that breaks the fiction. And, in most fantasy games, I'll agree a literal F-14 breaks the fiction to a greater or lesser degree. What to do about it? Declare that impossible and demand a different action, or work harder to translate? I say work harder.
How can what a player has a character visualize (think) break the fiction? I could have sworn that characters can think anything and it isn't the DMs job or purview to police character thought. Why is this different than gun powder or a printing press?
The ask for an F-14 is almost never going to be for the physical reality of an F-14, but for what that represents. You can talk with the player and find out what they're actually asking for in terms of abilities that they initially presented as an F-14 because that was their understood frame of reference. Once you do that, you can find a way to implement that into the fiction in a way that doesn't break the fiction -- and, usually, it requires very little change! For example, you could implement an F-14 in the fiction as something with a very similar form factor but powered not by electronics and aviation kerosene, but magictech. The effect achieves what the player is asking for, via their reference frame, but now translated into the fiction in a way that doesn't break the fiction.
That seems like an awful lot of work to get into what a character was thinking and adjudicate it. I could have sworn that wasn't something adjudicable. It does mean our later worries about needing to wish for someway to refuel, or investigating how to create fuel, wouldn't have been as difficulty. :=_
But seriously, I'm pretty sure the folks who are open to pausing in the rare instances where something seems off for the game world could easily have that discussion with their player about what the player really wanted. I was just trying to figure out how everyone else would deal with it. Needing to be translated into fiction and not wanting to break genre feel like reasonable things to me. They don't seem to be in RAW and I'm not sure I would have thought to bring them up in session 0.