To "take something under advisement"

Solution 1:

It depends on context and you are talking to, but it may well suggest that you are far from considering the issue in question:

Take something under advisement: (TFD)

• to hear an idea and think about it carefully. It's a good idea, but I'll have to take it under advisement. The suggestion was taken under advisement, and a reply was not expected for at least a month

Take under advisement (Urban Dictionary)

• The proper response to someone who request or advises you to do something you have no intention of doing.

Solution 2:

It literally means "to take away, consider and get advice on". When used literally it essentially means "to consider deeply". But as with most English idioms it can be used ironically, for emphasis - and is often used so. Thus the meaning asked about of "to ignore the advice" is simply the ironic use of the phrase.

Solution 3:

It literally functions the same as saying,

I'll take that under consideration.

So far as I know, there is little difference in the connotation, either. My experience would suggest, "I've thought about it already and chosen a route. What you're saying might make sense, but it'll probably be more trouble than I'm willing to commit to really compare your suggestion with the route already chosen."

Solution 4:

This is a useful phrase in response to a suggestion (good or bad) or information (good or bad, relevent or irrelevent.) The point is that hear what's being said and are not taking a position on it at this time. The speaker might or might not have a position already but they are not committing to it. It's also a way to accept input while reminding someone that they aren't your supervisor.

When used informally it can be humorous or ironic, as has been pointed out.