Ordem FAA JO 7110.65W - Procedimentos ATC, Capítulo 10 descreve como o ATC deve lidar com procedimentos para situações de emergência.
Na primeira seção, no entanto, diz:
10-1-1(d)
Because of the infinite variety of possible emergency situations, specific procedures cannot be prescribed. However, when you believe an emergency exists or is imminent, select and pursue a course of action which appears to be most appropriate under the circumstances and which most nearly conforms to the instructions in this manual.
Então, para Mayday e Pan-Pan, diz em 10-1-1 (a):
A pilot who encounters a Distress condition should declare an emergency by beginning the initial communication with the word “Mayday,” preferably repeated three times. For an Urgency condition, the word “Pan-Pan” should be used in the same manner.
O uso de Mayday e Pan-Pan declara uma emergência, mas não diz ao ATC sobre a natureza dessa emergência. Portanto, apenas dizer essas palavras não aciona nenhum método específico para lidar com a emergência, exceto o controlador que descarrega o tráfego e dá prioridade ao manuseio. Provavelmente também irá desencadear uma limpeza do espaço aéreo ao seu redor, e se você estiver no final ou perto de um aeroporto, um porão de terra.
Para o Medevac:
2-1-4 (b) esboços:
Provide priority to civilian air ambulance flights (call sign “MEDEVAC”). Use of the MEDEVAC call sign indicates that operational priority is requested. When verbally requested, provide priority to AIR EVAC, HOSP, and scheduled air carrier/air taxi flights. Assist the pilots of MEDEVAC, AIR EVAC, and HOSP aircraft to avoid areas of significant weather and turbulent conditions. When requested by a pilot, provide notifications to expedite ground handling of patients, vital organs, or urgently needed medical materials.
NOTE−
It is recognized that heavy traffic flow may affect the controller’s ability to provide priority handling. However, without compromising safety, good judgment must be used in each situation to facilitate the most expeditious movement of a MEDEVAC aircraft.
Para combustível mínimo
2-1-8 Esboços:
If an aircraft declares a state of “minimum fuel,” inform any facility to whom control jurisdiction is transferred of the minimum fuel problem and be alert for any occurrence which might delay the aircraft en route.
NOTE− Use of the term “minimum fuel” indicates recognition by a pilot that his/her fuel supply has reached a state where, upon reaching destination, he/she cannot accept any undue delay. This is not an emergency situation but merely an advisory that indicates an emergency situation is possible should any undue delay occur. A minimum fuel advisory does not imply a need for traffic priority. Common sense and good judgment will determine the extent of assistance to be given in minimum fuel situations. If, at any time, the remaining usable fuel supply suggests the need for traffic priority to ensure a safe landing, the pilot should declare an emergency and report fuel remaining in minutes.
(ênfase minha)
Realmente você deve ler todo o documento (longo) para ver como o ATC deve se comportar em certas situações. O Capítulo 2, Seção 1, tem muitas situações de "emergência", mas a maior parte se resume a dar prioridade e assistência que o piloto pede.