IIRC there was a difference of opinion between RSZ and Rav Elyashiv of why melacha in a airport would be mutar.
According to Rav Elyashiv - since an airport is outside the techum it therefore doesn't have the status of the Ir (Similar to the Svara of RYB).
According to RSZ- in an airport there is no chashad of Maras Ayin, in a regular place if one sees one doing melacha his first reaction, hey, why is he doing melacha and then only afterwards might he realise that he's a ben EY.
In a airport however, since it is for travelling - people will autimatically assume that hes a ben EY and that's why he's doing melacha. Since there is no Chashad, Chazal weren't gozer.
According, there would potentially be a nafka mina if one landed in a airport which is the city...