Você já tem uma boa resposta sobre separação especificamente, mas vale a pena notar que existem algumas regras gerais sobre vôos de formação em 14 CFR 91 :
As regras de formação mais específicas estão em 91.111:
§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.
Voos de caridade estão isentos de exigências de transportadora aérea (parte 119) e teste de drogas / álcool (parte 120), mas somente se o voo não for um voo de formação (entre outras condições):
§91.146 Passenger-carrying flights for the benefit of a charitable,
nonprofit, or community event.
[...]
(4) The flight is not an aerobatic or a formation flight;
Você deve fornecer detalhes de formação se estiver preenchendo um plano de voo VFR:
§91.153 VFR flight plan: Information required.
(a) Information required. Unless otherwise authorized by ATC, each
person filing a VFR flight plan shall include in it the following
information:
[...]
(2) The type of the aircraft or, in the case of a formation flight,
the type of each aircraft and the number of aircraft in the formation.
(3) The full name and address of the pilot in command or, in the case
of a formation flight, the formation commander.