Different languages convey nuance with different mechanics. The only reason an English speaker would say "He said he would be at the airport" is to convey nuance.
Fair enough, but the interesting tidbit is that in Turkish you can add a verb ending that implies reportedness and that's interesting in itself and not present in English.
+ He said he would be at the airport
+ He said he would be at the airport
+ He said he would be at the airport
+ He said he would be at the airport