As explained by Facebook:
"For example, let’s say people are looking at holiday trips to Mexico by browsing several airline sites and flight pricing apps. Airline brands will now be able to use Flight Ads to reach those people with tailored ads promoting relevant flight routes. In addition, travelers that visit a travel-related Facebook Page, but have not yet chosen a trip destination may see an ad to visit an airline brand’s site."
Up till now, airlines have only been able to use Travel Ads to re-target customers who'd visited their website or app, and were searching for a particular flight, but now, airlines will be able to reach more consumers who've expressed interest in travel.
Given the aspirational nature of social media platforms, it makes sense for Facebook to provide options to better target prospective travelers. Back in 2016, Facebook conducted a study which showed that 53% of travelers found holiday inspiration on Facebook, while those same users were also spending 5x more time on Facebook than on travel-related apps and sites in the planning process.
Facebook added 'Trip Consideration' options to their Travel Ads back in March, and these new, airline-specific options build on that, enabling brands to tap into user intent and better reach prospective buyers.