time - Use of the present continuous to refer to timetabled events

One of the things that is constantly confusing for English language learners, but comes with ease to native speakers, is when to use present continuous and when to use present simple.

Because of this, there are long lists of specific situations where students have to learn which tense is used for what.

For example, we use present simple for a re-occuring or habitual event "I walk home with Josh at 5:00pm" (implies this is a regular occurrence), whereas we use present continuous for a one off future planned event "I'm walking home with Josh at 5:00pm" (I'm doing that later today).

However, one thing that I keep seeing crop up in textbooks is the idea of "timetabled events". This is always left undefined, and is not really clear what it means. The typical example given is "the plane leaves at 3 tomorrow".

But honestly, I'm sure I'm just as likely to use the expression "the plane's leaving at 3 tomorrow."

Which tense to you think you would use, and should the use of the continuous here be viewed as "incorrect"?