Krdytkyu

From your comments:

Actually management has make promotion exam in english to enhance Englsh understanding better which helps to understand technical orders mainly in English

This sounds to me as if there is a valid business reason why the role requires a decent understanding of English.

Rather than arguing for an exception why not approach the worker like so:

I really think you've got the skills and experience to do very well in the Foreman position which would be a good promotion for you. Unfortunately your English level is currently too low for you to pass the exam. Have you ever thought of taking some online/night/weekend classes to try and improve your English?

Why do you need to promote him to the supervisor's category?

What you've said is that he's an excellent engineer. Great. He's also pretty bad at English. Okay. In his current position, his lack of ability at English isn't slowing him down. As a supervisor, it would be. Further, he has to know this. If he was really motivated to be a supervisor, he probably would have put some more effort into learning English sometime within the past five years.

So if he isn't super-motivated to be a supervisor, and he has a weakness in his skill set that would hamper him as a supervisor but doesn't slow him down where he is... maybe he shouldn't be a supervisor.

Of course, that still leaves you where you are, where this particular worker is more dedicated and skilled than you'd expect out of anyone who wasn't a supervisor. He's a special case in that. So... why not try to address it from that direction? Instead of trying to push him through as a supervisor, try get the man a bit more money (as raise or in bonuses) in the slot that he's in - the one in which he's shown particular excellence.

Really, the worst thing that could happen here would be if you promoted him and (due to lack of skill in English) he wasn't successful. Then you've gone from having an excellent engineer to having a mediocre-at-best supervisor (quite possibly with plummeting morale), and that's no good for anyone.

If this person truly is a valuable asset to your company, I would suggest partnering with him and having the company provide paid rudimentary training in English for him. Depending on the size of your company, it might also promote goodwill within the employees to offer this to anyone interested. If orders are given in English, I would think that having multiple employees being able to understand the orders as-given would be an asset. Maybe have a tutor brought in and provide training during lunches or other time so your employees can learn (if they wish), and not take significant time away from their regular duties.

Though I would suggest trying to make sure that the English tutoring be targeted towards the specific needs of the job and exam. There is likely little need to go into the whole complexity of the English language if a subset of the language is sufficient for the orders and tasks at hand.

Based on the phrasing of your OP I'm presuming you are above this person in your organization, so this answer is written from that perspective.

Have you considered asking this employee his opinion? Mention to him that you think he would make a good supervisor, and you would be happy to promote him if he improved his English, and see what he says. If he commits to improving his English, then you should assist him in any way you can to do so. However, there's a possibility he's just happy where he is; after all it's been 25 years and he hasn't complained at all so far (or at least if he has you didn't include it in your OP). Maybe he just doesn't want to put in the effort, and he's happy just being an engineer.

In either case, probably you should start by asking him what his aspirations are and go from there.

Not everybody who is a good worker is also necessarily a good supervisor.

The oral exam most likely doesn't test knowledge at all but covertly tries to assess the presence of soft skills in prospective supervisors. For the same reason, most likely, the annual assessments are weighted in to get an impression not on the quality of work, but on the "overall thing", how a person interacts in the work process and with the immediate supervisor, if there's friction, etc.

If being a supervisor was about skill and knowledge, the requirement of a minimum of 20 years of service alone would be enough. You cannot do a job for 20 years without acquiring skill and knowledge (not unless all your supervisors are complete idiots, or unless you are a public officer who cannot be fired unless caught committing a crime).

If you are in a job for 5-10 years and you show no signs of serious competence, you soon find yourself out of a job at the next restructuring occasion. Thus, 20 years is pretty much a guarantee on skill, no test necessary.

The exams are in English, which suggests that English is a language that is being spoken in that company. Obviously, for a supervisor being able to communicate properly with his subordinates, he should be fluent in that language. The written test, too, most likely doesn't verify knowledge, at least not primarily. Again, knowledge is not so much a dominating factor for someone with 20 years of experience.

You can, however, use a written test to assess language skills and the general ability to identify and analyze problems, and to find appropriate solutions (and many other things, it depends on how exactly the test is conceived).

So... hard as it sounds, no matter how well this guy does his job and no matter how diligent and nice he may be. If he cannot do the test, then he probably simply isn't qualified as supervisor.

The company policy on English language skills with the reason given is a worthy policy, but in this case it goes contrary to company goals.

Obviously, the goals of the promotion rules are to ensure that qualified personal gets promoted. The goals of the English requirement are different from that (development of people). If the two goals conflict, the more important one should take precendence and this worker and his skills need to be used to the greatest advantage of the company.

Allow for exceptions to the English rule, while keeping them exceptions, allows both goals to be followed in the optimal way. Insisting too strictly on the language rule is to the disadvantage of the company.

In essence: You argue using company goals and company benefits as the primary arguments. The fact that the worker deserves something is irrelevant in your argument, but that the company is missing out on advantages cannot be ignored.

Since there is no requirement stated in the policy for him to be fluent in English, have the exams translated into his native language. Provide technical interpreters if required.

This should be no more of a barrier than a no-impact disability.

He may enough English to provide direction, but I would think after 25 years, he has that. Possibly German as well, the nouns are generally always picked up.
(Kardan, Kolben, Kupplung, etc.)

You certainly can circumvent policy for his merit and in this case I would be a bit inclined to say its justified given that he makes a good fit for the role, assuming that his non-knowledge of English isn't a pre-requisite of that role and he would only need English to take the test.

Beware though that special rules and favorable treatment (no matter how deserving it seems to you) may open an entirely new can of worms down the line, as others may feel they are special enough to have preferential treatment as well.

As such you should be very delicate over how you treat this case to not leave room for misinterpretation and/or hurt feelings from fellow workers. Overall, a better solution would be, in case English knowledge isn't required for the foreman role to change the policy for everyone, so people may take the tests in other languages as well.

Unless all his coworkers speak his minority language then this is the wrong way to reward him. Making him foreman would be a disaster since he would be unable to communicate properly and you would also lose your best machinist.

Your best avenue of reward is to increase his pay. Not to make his work harder, responsibilities more and set him up for failure.

Not everyone wants "promotions" - he may be happy in his current role.

Some people are very good at getting work done but they make terrible leads or bosses.