Just in case of any aircraft is very short on fuel the pilot MUST declare 'proceeding for landing' even though he/she hasn't got the ATC CLEARANCE.
The ATC will devote full attention to the aircraft with "run of fuel" declaratory (It is Law Declaratory). All other aircraft lose their priorities, even if other aircraft has declared "supposed fuel leak".
The aircraft declaring "run of fuel" and "proceeding to land" takes over the highest priority even though it hasn’t got proper authorization from ATC. It is in the same priority of GLIDERS because it has lost its own propulsion system.
2° Aircraft in Aero-medical service (wounded or seriously injured)
3° Aircraft operational SAR (search and rescue)
4° Aircraft in Military Operation (War mission)
5° Aircraft carrying the President of the Nation
6° Aircraft in Military (Military Maneuver)
7° Other Aircraft
2° Aeronaves em serviço aeromedico (Enfermo ou Ferido grave)
3° Aeronaves em operação SAR (Busca e Salvamento)
4° Aeronaves em Operação Militar (Missão de Guerra)
5° Aeronave transportando o Presidente da República
6° Aeronaves em Operação Militar (Manobra Militar)
7° Demais Aeronaves