M600 SLS From Piper Aircraft Piper Aircraft has been quiet in recent times but they are back in the news because of a revamp of the top-of-the-line M600. The new next-gen variant is called the M600 SLS. What's different about the SLS versus the standard M600 we have been accustomed to? Firstly, the SLS stands for Safety Luxury and Support which gives an idea the direction we are going in with this aircraft. The M600 SLS has something called the HALO System which is keep in this new very automated aircraft. HALO will essentially be the new certification for Garmin's Auto-land technology.