Originally Posted by Aus_Mal
I agree that O7 is a little weird.
However, OZ was already taken. OJ doesn't seem to be taken - but they may not have wanted to be compared to Orange Juice and/or confused with DJ.
Unfortunately, the 'OJ' designator is taken as well by Overland Airways Limited of Nigeria. This leaves OzJet with little choice since all two letter codes that begins with O has been taken up already.
Have a look
here under 'airline codes'...