We try not to make big bold claims about "if you have X, you're legal", because flight situations and the information that they require are subject to some interpretation.
91.503 says "The pilot in command of an airplane shall ensure that the following flying equipment and aeronautical charts and data, in current and appropriate form, are accessible for each flight[…]Pertinent aeronautical charts.".
91.103 also has more. "Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight... This information must include - (a) For a flight under IFR or a flight not in the vicinity of an airport, weather reports and forecasts, fuel requirements, alternatives available if the planned flight cannot be completed, and any known traffic delays of which the pilot in command has been advised by ATC;
(b) For any flight, runway lengths at airports of intended use, and the following takeoff and landing distance information:
...
(2) For civil aircraft other than those specified in paragraph (b)(1) of this section, other reliable information appropriate to the aircraft, relating to aircraft performance under expected values of airport elevation and runway slope, aircraft gross weight, and wind and temperature."
So SkyView's digital databases have practically all of the gov't-provided information that you'd find on an aeronautical chart /AFD, with the caveat that the "paper" versions of the charts sometimes have a bit extra information that isn't encoded in the digital data. An example of that is the preferred VFR procedures to cross Sea-Tac's class B here in Seattle. So does that violate the spirit of not having an aeronautical chart, when the data that your SkyView system displays comes from the same gov't-provided dataset that the charting office uses to make the paper sectionals? One could argue it both ways. If you want to be double extra sure, remember that the digitized versions of the paper charts are available from Seattle Avionics for $99/year.
