AERONAUTICS Feature on Englewood aviation safety device manufacturer, Frost Engineering. Denver Business Journal v.39 #12 D 14, 1987 p.1,27 British aircraft Optica combines traits of helicopter and airplane. RMN Ag 30, 1988 p.8 Commuter airlines have greater share of fatalities. RMN S 29, 1988 p.20 Ethanol-powered plane demonstrates alternative fuels. RMN 0 3, 1988 p.18,23 0.