I just returned from two weeks of assignment work in Alaska, and as usual had a ton of gear with me. Lights for interiors, prime lenses for portraits, travel zooms…and of course the big 600mm F4 for wildlife. While the other gear fits nicely into rollers and backpacks, the 600mm is a beast. But one look at a distant puffin through that lens and carrying it around would be worth it.
The best way to travel with this lens, both on the trail and in the airport, is using the Tamrac Anvil Super 25. This pack is actually a backpack that can carry the lens on the trail and in the field. The Anvil 25 has a full suspension system, and carries very nicely. The case comes with a waterproof cover, so walking in the rain is not a problem. Better yet, the case is just big enough for me to carry my 600mm F4 with a D850 attached. Hiking to distant bird rookeries is no problem. Outside straps and buckles allow attaching a tripod as well.
While you could get this case into most overhead compartments, if you luck out and no space is available, how do you carry the big lens onto the tiny commuter plane?
Try using a LensCoat TravelCoat. These coast are neoprene, and fit like a glove on your lens. The TravelCoat does a great job of protecting your lens from scotches and small bangs. When I boarded my 30 seat plane for the Pribilofs, there was no overhead space that could take my 600mm in a pack. But I carried on my lens in a TravelCoat, and it fit nicely below the seat in front of me. This is a great option for hand carrying the lens onto very planes with minimal space.