Does anyone know why whenever I input a block fuel value, it calculates my trip fuel, reserve, and final, but leaves the alternate and extra time lines blank?It worked fine for me when I flew a flight between LAX and SFO earlier today. I'm trying a longer haul between SFO and ANC and now it's not giving me any values.

After some testing, I finally figured out what the problem was.I was using PAED as my alternate airport and because of that entry it wasn't displaying alternate and extra fuel values in the MCDU.The airport is approximately 7nm away from Anchorage. Could the distance between the two have anything to do with it?Does anyone know the FMC is behaving like this?

Not really sure about the distance, but do you really want an alternate that's just 7nm away?

The weather in the area was fine. I didn't feel like searching for another nearby alternate and Fairbanks was pretty far.

Hi,this happens:a ) when your alternate airport isn't available in AIRAC Database on principleb ) or you have chosen an alternate Airports with runways smaller than 6000ft and the corresponding option active.

I noticed that the extra/time result field doesn't refresh after entering a new BLOCK value until I press something else on the FMS. A bug I guess. To workaround, I press CLR twice after entering my BLOCK value and then the FMS will run the calculations.(yeah, old post I know :) )

Edited January 12, 201214 yr by clarkTX