Dear Gurus,
There is a dialogue from the recording:

A: When is your flight? - B: It’s AB1234 from Paris at 14:10. It’s /due in to London/ at 15:10.
A: That’s /AB1234 in to London/ at 15:10. Is that right? - B: That’s right.

Above, I used /.../ to point to the words I'm asking about.
As you see, there are two similar segments:
1) /due in to London/
2) /AB1234 in to London/

To my ears, both (1) and (2) sound exactly like I spelled them above. However, it seems like before I met something like /due into/ making 'into' a one word without that space between 'in' and 'to'.

So, could you please tell me whether my spelling (1) and (2) correct or not? Is that 'due in to' or 'due into'?
Thank you!

Question

Dear Gurus,
There is a dialogue from the recording:

A: When is your flight? - B: It’s AB1234 from Paris at 14:10. It’s /due in to London/ at 15:10. 
A: That’s /AB1234 in to London/ at 15:10. Is that right? - B: That’s right.

Above, I used /.../ to point to the words I'm asking about. 
As you see, there are two similar segments:
1)  /due in to London/ 
2) /AB1234 in to London/

To my ears, both (1) and (2) sound exactly like I spelled them above. However, it seems like before I met something like /due into/ making 'into' a one word without that space between 'in' and 'to'.

So, could you please tell me whether my spelling (1) and (2) correct or not? Is that 'due in to' or 'due into'?
Thank you!

Answer

I would use "into" for both of these cases.  The context gives us a sense of directionality: the plane will be flying "into" the airport at a certain time.  It's true that we can also say things like, "When does your flight come in?" or "My plane gets in at nine," and we can also say that we have a flight "to" London, or that we're flying "to London."  So I can see why it seems like you could use "in" and "to" separately.  But when we're talking about something entering a place or area, it makes sense to use the word "into" to describe the motion.