Slightly off topic, but in some ways it looks more like C than C++. For example, C++ provides classes such as std::vector which effectively replace arrays for code such as this, making the programmer's life easier. And I would expect those string fields in your FlightType structure to be type std::string.
Returning to your question, sorry, I'm not sure what you mean by 'update'. If you know the index of your array entry, just write to one of its fields using something like:
But I'm guessing that wasn't what you were asking; please could you clarify?