While I may not agree with the earlier poster's phrasing, I agree fully with his sentiment. RPGs are not (and should not be, IMO) a low-level simulation game.
Most things in Traveller are pretty high level (abstract) simulations. Abruptly, when it goes into combat, this suddenly changes. I feel it's the place where a lot of these RPGs (including Traveller) show they were developed from wargamers or written by wargamers. What was a reasonably abstract exercise in wish-fulfillment becomes a tactical mid- or low-level simulation, with the range grid coming out (or even a hex grid and miniatures) and many Refs expecting detailed answers on squad deployment, spotting assets, and where the support weapons are being deployed. Range and movement maximums come into play and injury modifiers and similar stuff ... this level of detail doesn't exist for other skills in Traveller, though it's hilarious to imagine it happening:
"Okay, here's the diagram of 777's cockpit, the these lights are showing red and this one says NO VOR, what do you do and in what steps? You have 30 seconds to answer."
Just because the Ref is a certified 777 pilot doesn't make it okay to do things like this to their players.
So, how would you deal with a player, or even players, that have characters that are radically different from the player's own experience and background?
I feel you have to abstract it in that case. It's okay to let skill rolls handle it in this case. As a GM I feel you have to be generous, not strict, in your interpretation of a what a character knows. Traveller is a skills light system, especially the earlier editions, but no RPG, even GURPS with its overlong lists of skills can actually ever cover all the nuanced skills that characters would (or should) have. One of the drawbacks of Traveller's die-roll skills assignment is that you can have characters who curiously lack skills you'd think are required for a role but they never got them because of the rolls during chargen ("Your marine was a SEH winner 5 term gunnery sergeant who led a squad and he never got Tactics?" "Die rolls."). Some skills just don't exist in Traveller.
At the extreme end of high-level abstraction, there's little interaction and everything is handled by die-rolls. At the other extreme, low-level (or low abstraction) nobody can play a character that is not them and it stops being a game about a future alternate universe and becomes some odd exercise in 21st century people cosplaying living in a future where all the technologies and situations are those of the 21st century. Where you and your group falls is likely somewhere in the middle. Every gaming group has a level that they're comfortable it, but it's not a static thing; the group's comfort level with things like this can change between sessions.
There's a "trap game" mentality which is a danger I think all GMs can fall into if we're not careful - where Traveller changes from a high-level simulation to a low-level simulation abruptly when it's something the GM knows something about:
Player: "I go hunting for a bear."
GM: "Well as a matter of fact, I lived in the hill country in West Virginia most of my years until I went to college and have done some bear hunting ... describe to me how you do this."
Yet, this same GM is perfectly content just rolling dice when the Engineer wants to repair the Jump Drive and doesn't expect this level of detail because it's something that the GM doesn't know anything about.
This is wrong and we as GMs have to avoid doing it I feel. We have no idea how jump drive work, so anything involving it are abstract skills but just because something has a real world analogue (especially combat), Traveller should not become a vengeful penalty game where it is akin to the players walking around an unmarked minefield and only the GM knows where the mines are. One wrong answer and boom. (Until you have that player who spent 4 years in Africa clearing mines as part of an NGO and the GM gets their come-uppance of "well actually ...")
It's also the responsibility of players: I tell my players it is well within their rights if I start expecting them to describe some action in detail (eg; I start going down the penalty game route) they can flat out tell me, "It's my character who's an expert at this, not me. You tell me." In addition, I usually tell my players if it's an application of a skill they know nothing about, it's okay for them to keep their actions relatively vague and make me fill in the blanks in the narrative.
I think the idea of a "forecasting" or "estimation" check is fine. If you as the GM (remember, I feel GMs should be generous rather than strict with this) feel the player is about to do something questionable that their character would know better than doing, it's fine to tell the player (before the action is undertaken) the risks involved in their proposed action and let them reconsider - I usually lay out of them what their likely paths are, what the hazards/level of risk is for each path. Then I let them choose which action they take based on the risks/rewards. This is for combat. But it is applicable to other skills as well, fortunately, most gamers typically don't expect this level of detail with a lot of other tasks, but it's still okay have a Mechanic (or Doctor) for instance, make a roll before the actual action: "You have a pretty good idea of what the problem is, but you lack the skills to fix it / you'll need some items you don't have to fix it / you can't really heal this person but you can stabilize them for an hour or two during which they'll need to be transported somewhere with proper medical facilities"
This idea of "not making players roleplay skills they don't have but their characters do" has made me change how I view encumberance/load on a character as well; a character experienced in mountaineering is going to have certain things on his or her person (and not have a bunch of things) compared to someone who has no idea about what mountaineering requires and is just choosing things from an "equipment list" of they imagine they might need. Again, I feel its unfair to ding players for not having the right items when their characters would know.
