Other flight groups dosent take off?

[SEE]

There is only one mission that has a second group taking off with your group but it only has one Spit in it, (this is the one you have seen flying around doing nothing much) the others you see are just parked and not part of any flightgroup, thay are just static actors, this is why they seem to stay put and do nothing. Thats is the only mission you will see this.