The U.S. executive charter market enjoyed a markedly stronger month in February than during the same month a year earlier, according to online charter booking portal CharterX. Midsize jets showed the strongest recovery, with a 25.9-percent year-over-year increase, to 15,509 flight hours. Heavy jets recovered by 12.3 percent, to 8,610 hours, and light jets climbed 11 percent, to 14,757 hours. Overall, flight hours last month were down slightly from January, but CharterX said this is in keeping with seasonal trends and the market continued to track the S&P 500 index fairly closely.