Betsy is a 5.1% abv unfiltered, bottled beer brewed by the Hong Kong Beer Co. which uses a lager yeast, English Fuggles as well as local New Terrritories hops and 60% wheat malt in the mash. It's named after the first DC-3 aircraft the company flew in its early days in the mid-40's. and supposedly has a flavour profile which works particularly well at thirty-five thousand feet. It all sounds a bit gimmicky to me.
Having a beer on the plane is a ritual which is part of most people's holidays, although you're most likely to get served the product of a global brewer like Amstel or Stella. The one beer I look forward to drinking when flying is Lufthansa's in-flight beer Warsteiner which always seems to have a bit more hoppiness than the average mass-market German Pils.