NetJets is adding in-flight Internet service from Aircell to another 100 or so aircraft in its fleet, Aircell announced yesterday. In 2010 the fractional operator initially opted for Aircell Internet service aboard more than 250 of its jets, and the additional 100 systems will expand NetJets’ connected fleet by about 40 percent. The installation process is already under way at Duncan Aviation, and the entire retrofit program is expected to be completed by mid-2014.