The Princess and the Pilot (2011) on Netflix

Plot summary

The Levamme Empire and the Amatsukami Imperium have been at war for years. Prince Carlo Levamme proposes marriage to Juana del Moral and promises to end the war within a year. When the Amatsukami hear of it, they attack the del Moral home and target Juana. The San Maltilia Airforce hands the task of carrying her to the prince in secret to Charles Karino, a mercenary flyer of mixed Amatsuvian and Levammian blood, the kingdom's most skilled pilot, who outperforms elite airmen in combat exercises yet is refused recognition as a flying ace. He is to take the seaplane Santa Cruz 12,000 kilometers through enemy territory while other mercenary units fly diversions.