Canadian airspace
...that there are parts of Canadian airspace where compasses are not useful because they are too close to the magnetic north pole?
...that there are parts of <b id="mwA20"><a href="./Canadian_airspace" id="mwA24" rel="mw:WikiLink" title="Canadian airspace">Canadian airspace</a></b> where compasses are not useful because they are too close to the <a class="mw-redirect" href="./North_pole#Magnetic_North" id="mwA28" rel="mw:WikiLink" title="North pole">magnetic north pole</a>?