She is an air-hostess in a flight.

[tufguy]

1) She is an air-hostess in a flight.

2) She is working with a company as an air-hostess.

3) She is working with a flight as an air-hostess.

Please check my sentences.

 

[emsr2d2]

People don't just work on one flight (one journey from A to B) as an air hostess/air stewardess, so both 1 and 3 are wrong. 2 is OK but as far as I know you can't be a self-employed air hostess so it's redundant to say "with a company".

She is an air hostess.
She works as an air hostess.
She is working as an air hostess.

If you want to mention the company, use its name. "She's an air hostess for/with British Airways" or "She's a BA air hostess".

In BrE, "air stewardess" is more common than "air hostess" but, in fact, "flight crew" is the more common these days and refers to both sexes.

 

[tzfujimino]

How about "a flight attendant"?
Is it common enough in BrE?

 

[andrewg927]

You can also use "flight attendant".

 

[emsr2d2]

How about "a flight attendant"?
Is it common enough in BrE?

Yes, that's common in BrE too.

 

[Tdol]

Air hostess is seen as a bit old-fashioned by many, especially as we don't say air host for men, where flight attendant works for everyone.