Is there any advantage to running AN brake fittings ?

The single flare using a tube nut & sleeve for an AN fitting is easier to do than a standard double flare or ISO "bubble" flare used on brake lines.

It's pretty easy to botch a double flare if you don't prep the tube right or position the flaring tool right for the first stage, doing a single flare for the AN fitting is quite a bit easier.

Yeah, but AN fitting are not flared with the same flaring tool as automotive flares.

Is one more leak proof than the other ? Seems like all the circle track guys use AN.Maybe because they tear their cars apart often.Is it easier to work with ?

AN fittings are 47 degree flared they are used in aviation applications with little if any problems as long as they are not overtorqued causing lines to split.

actually AN fittings use a 37 degree flare and the double flare on our cars is 45 degrees. You can screw AN flares up to, the best thing to do is to know what your doing. I am an A&P mechanic, and I've seen plenty of AN fittings leek. The downsides are that the fittings can easily strip, if you use aluminum and they are not properly aligned, Also the flares can crack because they are thinner. Done properly AN fittings are easier to work with though.

IMO its just an AN coolness factor for brake lines.

duh thats what i meant 37 degree. Im an A&P also and the biggest problems I have seen with AN fittings is lines splitting due to overtorque, they are easier to work with, but you still have to be aware of what you are doing.