The Turkish flight at this time brings not only one passenger. Sorry sometimes it is better to give no reply then a wrong one.
There is an exchange open, when you come for a special reason. Sometimes people don't have Dollars for the visa. so they have to change Euro in USD. That's why it has to be open.
Out of the exit gate right hand you see the ATM. Normally it is very well stocked. But because this is an EXIM Bank ATM it gives only 300,000 TZS with the same fees which Barclays or CRDB give 400,000. To change at the Airport Forex I recommend to change only a small amount, the rate is not good. Better to go next day to roundabout area in Arusha, there are many Forex and competition makes rates better. If you go only to Usa River halfway to Arusha, then in Rotterdam compund is Forex with the same rates like Arusha.
For cash USD nowadays it is much better to take only the new colored ones. (For instance 100 USD are blue).
Johannes
The Schimann Family