well maybe,
But I noticed when you create large number of planes this has a tendency to show up. What I noticed instead of creating one flight with a formation like ''Right Echelon". I created multiple flights with a formation of 'solo' to replace it adding a solo flight for each plane that should be in the echelon. Now this may not be possible for missions that have more than 40 planes in them but I did notice that it help with smaller missions that had more than 20. For instance the 'The Great Marianas Turkey Shoot' mission I created had this problem but after making the change the problem went away. Try it out in the mission editor and see if the problem goes away..
p.s -sudz- after doing a spell check here I just found out that Echelon is missspelled in the mission editor flight formation list...
