I'd like to clarify a misconception about flying VFR on top or OTP as the controller sees it in his flight plan and on the data block on the scope.  This clearance isn't a clearance for a free for all or going as low as you can go.  You are still on an IFR flight plan and must stay on the filed route.  The ONLY thing that does for you is allow you to stay clear of clouds.  You must still comply with VFR visibility, distance from cloud criteria, and the minimum IFR altitudes.  This last one is the biggy.  It takes the burden off the controller to separate you from the ground with minimum IFR separation (1000' AGL or 2000' AGL in mountainous terrain), and other IFR aircraft unless in class B or C airspace.  You are still required to comply with this altitude.   I saw this as a controller on many many occasions, and most controllers don't know what the pilot rules are (and don't really care), so if they tell you go as low as you want, that is not a clearance to break the FAR's.  You can be violated if you do this. (I've seen it happen).   I'd really hate for someone to get a violation on their record because they didn't understand the rules.  If you want to fly right right over Mt Rainier (less than 2000' AGL) and think you can do it VFR on top, you better be canceling IFR first.   There are waivers that the ATC facilities can get such as when flying over Pikes Peak just West of Colorado Springs.  The MIA (minimum IFR altitude) is 16000'MSL.  This is less than 2000 AGL, but ATC has authorization to do this.  Pilots don't have this authorization via a VFR on top clearance.  In this case you would have to be at least 16115' MSL (2000'AGL).
    Another point I'd like to bring up that goes along with this discussion is that you are not allowed to go Direct using GPS (or other RNAV equipment such as INS) in any controlled airspace unless you are receiving radar monitoring(except when within navaid limitations and going direct to a navaid).  What this means is that unless you are in radar contact, you cannot go direct.  I'm sure this has happened to some of you and you were frustrated by why you had to stay on an airway.  This is a huge issue in Alaska since there are so many non radar areas and so many remote airports.  Alaska had a waiver to be able to do this, but it expired last month.  I'm working on this very issue right now with flight standards and all the other affected offices here at the FAA, to allow GPS direct from airport to airport in non radar situations.  Once this is approved, we will hopefully be able to apply it in the lower 48 and you will all be going direct to your destination a lot more frequently.  As a side note, a loophole exists that allows you to go direct in non radar if you are on a VFR on top clearance, so keep that in mind and use the rules to your advantage when possible. 


Ron Galbraith


 
>i used to fly in this area of the Cascades all the time.  If you are on an ifr flight plan with a "vfr on top" clearance, ATC will let you go as low as you want.  One time, when on a VFR on top clearance near Mt Ranier,  I asked how low i could go....they said "you can taxi from there to here if you want".
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