Originally Posted by
Capt Scribble
EASA Rules dictate you arrive at destination with a minimum of 30 mins fuel at 1500ft plus diversion fuel. Once in the vicinity, you can burn off the diversion fuel. However, airports can close completely for events such as a drone or bomb warning. In the A321 that’s about 1500kg + Alt, normally around 2400kg (min).
EASA also lets you plan without alternate, so you can legally land with less fuel than that.