US Air Force C-5 Galaxy Air Refueling...

[Patriot Lover]

 

[Yaseen1]

this is the largest and heavy transport aircraft in u.s airforce and refueling can help it to avoid landing on any airbase and continue to move between far most places of world

 

[Ultima Thule]

this is the largest and heavy transport aircraft in u.s airforce and refueling can help it to avoid landing on any airbase and continue to move between far most places of world

Not for indefinite time, every aircraft has to come down for maintenance @Yaseen1