"They will be 1 1/2 to 2 nautical miles away from the leading aircraft, and slightly offset, which means they are on the side of the vortex. It's no longer the

"They will be 1 1/2 to 2 nautical miles away from the leading aircraft, and slightly offset, which means they are on the side of the vortex. It's no longer the vortex, it's the smooth current of rotating air which is next to the vortex, and we use the updraft of this air." Taking advantage of the free lift in this updraft of air is called "wake-energy retrieval." ... on long-haul flights, fuel savings of between 5% and 10% may be achieved, "which is an enormous number."