Normally two pegs as out the box.
Some things look better on one peg. Support ships like my HWK i put of three so it looks like they are standing off and doing 'comand and control' a little more
It might have been interesting to have an advance rule to allow number of pegs to show an abstract measure of 'height' in relation to other ships but it would be a pig to keep changing pegs and isnt *that* relevant in open space. In a ground attack varient telescopic bases for height would be excellent
(we did this at a fighter combat demo game at games day with GW once called 'air waagh' all the ork and imperial fighers were on heavy lead bases and mounted on car antennas/ariels so you could make them 6, 12 or 18" above ground)
Where pegs are in fact used as altitude indicators is in Wings of Glory (former Wings of War) WWII version. You have to play a climb maneuver for a few turns and gain altitude counters and every few counters you gain an altitude level and adf a peg under your Spitfires and Focke-Wulffs. Of course you can also dive back down which happens a lot faster!
In fact it's a nice idea, but in space combat as opposed to atmospheric combat it hardly makes any sense!
