Maintenance routes

First of all, Sorry if that was already posted somewhere.

I am thinking about, that u r able to open an route to the airport where u can do maintenance (for example from NGO u can open HND) but u can not send there normal flights. Only when u need maintenance. Is this for u ok?

Like I have opened it and now I have 1/15 routes. But can not improve, because u r unable to send your aircrafts. Som it will take me 10 planes to send for maintenance until I will reach 10 flight there and will be able to open another second route? Quite stupid