Questions on the FUEL PRED page on A320

[Asuspilot]

Hello all,

Hope you can help me out as I am trying to get my head around the FUEL PRED page on the A320. I have tried to attach an image from google that I found to help (hopefully it is accurate).
2684

The EFOB arriving at LTAN should be 3.6 tonnes
The EFOB at the alternate would be 2.4 tonnes

Not sure about the meaning for the route reserve.
The ALTN/TIME is the fuel required from the destination the alternate according to the flight plan?

The FINAL TIME is the holding time at 1500ft?

The EXTRA TIME is just that. At what point would you divert though? Once the EXTRA TIME has ended or can you then use the FINAL TIME on top after that before diverting.

Just trying to get to grips with this. Thanks for your help.

[hph304]

Route reserve is the contignency fuel. You can set either mass or a % of the trip fuel. Once airborne, this fuel is added to the extra fuel.

ATLN/TIME: The figure below ALTN is the amount of fuel required to the alternate. If hard tuned, as it is in this case with 1.2 tons, no time is displayed. If you leave the ALTN blank, the FMGS will calculate the amount of fuel required to your alternate and the flight time. For the best prediction you enter the alternate routing in the flightplan.

FINAL/TIME: figure below final is the final reserve fuel, time is the amount of minutes.

When you divert depends on the situation. You can either use all the extra fuel until you arrive at your min dest fob. At that point you would have to divert. You can of course also divert before touching your extra fuel.

If you start touching your final reserve fuel you become a fuel emergency.

[pineteam]

If the weather is not marginal, you don't have to divert. This is at PIC discretion and common sense. As long as you land with at least 30 min in the tank, no one can tell you anything. Obviously it's not a situation you want to be. But in good weather conditions with no or little delay expected for the approach, it's actually safer to cancel you alternate fuel and shoot the approach and land at destination instead of initiating a diversion to your alternate with zero extra fuel.. A slight delay or one go around and you are in a mayday fuel situation.