[FlyChicaga]

Two considerations:

First, we have a stipulation in our FOM that says we cannot depart without proper fuel reserves, but enroute delays or unexpected circumstances do not preclude us from burning into our reserves. Basically, we can burn into this fuel if we feel that using it is a more prudent decision than not.

Also, remember that the fuel reserves are for planning purposes. If you visualize the situation I have presented, you are between your destination and alternate. If you fly to your destination, go missed, then fly to your alternate, you will not likely have 45 minutes of fuel remaining. However, if you fly to your destination and land, or divert to your alternate and land without flying an approach at the destination first, you will land at either airport with well above 45 minutes of fuel remaining.

I have had this exact scenario twice in the past few months.