I eat in a mostly (not pure) Paleo style, kinda like keto but high protein, medium fat, low carb and as little processing or messing about with core ingredients as possible. When I want to go into Ketogenesis I mix paleo with Intermittent Fasting.

That said, airline/lounge food is terrible for this. Gluten Intolerant meals are the closest thing available, you are guaranteed to not get pasta. Most of the time it is grilled chicken or beef with little to no heavy sauce and for breakfast, almost always eggs of some type. (note: I fly mostly Star Alliance - but the concept of Gluten free is pretty universal) I have even had friends start to use GI special meals to avoid being stuck with pasta.

edit: this may not be good for nut allergies as the bread/desserts are usually the ones made with almond flour