Although the answer is most likely to be 'no', there are still some crews on certain airlines who may (very small possibility) allow a flight deck visit in flight.
This is correct,
I have been quite lucky on the Portuguese airlines . When i went back home to Portugal last year i got 3 out of 3 flight deck visits now if me being a student pilot, or Portuguese affected the decision i dont know, i always try to book flights when i know that a friend either the captain or FO will be on that flight.