management

[MEEMOO]

what is it appropriate for a manager to be dictorial?

[MEEMOO]

Sorry that should say when.

[buildersmate]

This sounds like you've been set an HR assignment to do. If so, I suggest you look at the Situational Leadership Model (originally developed by Hershey and Blanchard) which will give you ideas you could develop. The model talks about the balance of Directive behaviour by a manager versus Supportive behaviour when managing an employee. High directing with low supporting is what you are asking (though I wouldn't use the term dictatorial). Occasions when it may be appropriate include, when an employee is new and needs instructions to learn the job, when danger or risk demands specific instruction must be obeyed (H&S issue, or Army Commander on the battlefield)l

[parkesquay]

This is not a question that begats simple answers because there are many situations where time constraints don't allow either explanation or consultation. The easiest example of this would normally be military where for example, the NCO of a of a patrol orders his lads to 'get down' . Usually anybody who doesn't obey gets shot(by the enemy). Simplistic I know but relevant. Also, as buildersmate points out , if the person in charge of say a workshop sees somebody about to cut their hand off , a dictatorial approach can stop serious damage.
This is a massive subject. However we should always bear in mind that when it comes to the crunch our immediate superiors have to take full responsibility for subordinates actions and in order to achieve 'their' objectives it isn't always feasible/practical to offer a reason for their 'orders/demands. One's superior my be in possession of facts which is not in his/her remit to share or divulge. So maybe a general answer to your question could be - 'when it is not appropriate to act otherwise'