The V Flight Formationhas been found to be helpful in achieving greater fuel efficiency and range. Though it is currently used mostly for military purposes, what restricts it from being used for commercial purposes?
- You need to schedule a number of aircraft all flying the same route at the same time for a significant amount of time
- If different, competing airlines should participate in one formation then they have to cooperate and be satisfied that no one is at a commercial (dis)advantage
- A lot of work would need to be done on procedures and training (how does the formation form up, who takes the lead, how/when does the formation leader change, how are emergencies handled, what flight levels are used, what separation is required between formation and non-formation flights etc.)
- Autopilots, software and other equipment would need major updates, which in turn requires re-certification
- All relevant regulations on separation, formation flying and so on would need to be reviewed and changed which in most countries means changing the aviation laws, and changing any law is usually a long, slow process
Having said all that, you'll notice that most of those issues are procedural, not technical. In theory it's a viable approach, but turning that theory into reality would require a lot of work.
Formation flight is not allowed by the FAA when carrying paying passengers:
from 14 CFR 91:
§91.111 Operating near other aircraft.
(a) No person may operate an aircraft so close to another aircraft as to create a collision hazard.
(b) No person may operate an aircraft in formation flight except by arrangement with the pilot in command of each aircraft in the formation.
(c) No person may operate an aircraft, carrying passengers for hire, in formation flight.
The core reason would be safety. If any craft has a problem it needs to be able to get out of formation safely and pilots need to be trained for it. Also flying at cruise requires the autopilot; however no current civilian autopilot can make adjustments to account for maintaining separation in formation flight.
As a passenger I wish:
- To have a good choice of flight times
- Not to have to wait a long time while other aircraft are unloading
- Not to have long queues
- Not to have my flight be delayed due to issues with another flight
The above does not sit well with 'You need to schedule a number of aircraft all flying the same route at the same time for a significant amount of time'.