use of on and in

Why do we say 'in a helicopter' but 'on a plane'; 'in a boat' but 'on a ship';'in a car' but ' on a bus'? this is a confusion i can't find an answer to.

There is no answer :)
You have to memorise these prepositions, like in French as with many other languages. (or had the chance of growing up with the language)

what a confusion with surface and enclosed space. as a teacher of english most of my adult learners keep asking these questions and prepositions and phrasal verbs leave them bemused.
thankyou mike. you have made me feel better as i too thought there was no rule behind that usage.
mridula

English teachers try to explain what has no explanation,
you have to memorize to use at, on and in,

I was an Enlgish teacher for foreigners for more than 7 years.
When my students came up with the question "When do you use at, in and on?" I always told them to learn the particular cases BY HEART. The solution is to listen to a lot of Enlgish so that you develop the feeling of what is / isn't correct. I used to tell them that learning any rule for these prepositions was not really helpful, since the cases in which they are used are many times contradictory.

Exactly. Each case has to be learned individually. Many languages, such as Russian, are the same way in their use of prepositions.

Love is in the air.
Radio is on the air.

Check in your brain, not on your head.

The men are tough.
The women are fine.

Dha men ar tuf.
Dha wimmin ar fein.

"Love Is In The Air" is on the radio.

On: means like above or about something working with.

In: means interior, not exterior or in the space of something although plain or flat.

in

http://www.dictionary.cambridge.org/results.asp?searchword=in&image.x=25&image.y=11

on

http://www.dictionary.cambridge.org/results.asp?searchword=on&image.x=36&image.y=9

I'm not a dictionary. I just guess with my own words about.

Yes, it is always difficult to learn preposition, because there are a lot of exceptions.