How to calculate Maintenance Fees

[HOCC Airline]

As I have found in #506, the maintenance fee makes me in trouble, but I cannot determine which kinds of planes burden me more, and hence I cannot perform suitable preventive actions.
Is there any mechanism for allowing the Bosses (i.e. the players) to know the distribution of maintenance fees of specific planes?

Thanks for answering.

[pseudoswede]

The exact maintenance fee formula has not been made public--nor will it be released. However, there are a few guidelines to reduce maintenance fees...

* Avoid old planes available on the used market -- typically anything older than 3 years old.
* Avoid any plane over $200M, unless you want to replace it every 6-12 months.
* The more expensive the plane, the quicker you need to replace it.
* You incur maintenance fees whether your plane is on routes or sitting around--so avoid having too many planes hanging around.

[XeniaAirways]

I know a general rule of thumb is that new aircraft can be operated with high profit margins up to around 3 years of age.  However, acquiring used, aircraft at a discount price is not a bad choice either.