In the US, how does the distinction between E2 and E3/E4 airspace affect pilots?
&quot;Caution: as noted in the links below, in actual practice, the distinction between E2 airspace and E3/E4 (&quot;extension&quot;) airspace is often ignored by ATC...&quot;
In the Center environment, we make no distinction between the surface area and the extensions when dealing with SVFR. The reason is simple. I can't clear a SVFR and an IFR in that airspace at the same time (or two SVFR aircraft), so those extensions should be empty if I'm allowing SVFR. Conversely, I'll not allow a SFVR operation (remember, the pilot has to request it), if I have an IFR aircraft cleared in that surface area.
In the case of Class E that's adjacent to Class C or D airspace, the pilot should be talking to ATC, anyway.
Keep in mind, though, if you're just buzzing along VFR and you see that there's a surface area ahead of you, there's nothing wrong with calling Center and asking if there's known traffic there, or even requesting flight following (cheap insurance!) through the area.