N139BG

N139BG is a Grob G103 Twin Astir operated by PHILADELPHIA GLIDER COUNCIL INC. SkyMeter has tracked 800 flights totalling 286 hours of airtime via ADS-B across 2 callsigns. The most frequent segment is KCKZ to KCKZ. Service window in our records spans 388 days. Of those flights, 18 (2.2%) carry at least one detected incident: a go-around, unstable approach, stall warning, or runway excursion. The Grob G103 Twin Astir has a maximum takeoff weight of 1,212 lb, light wake category.

About the Grob G103 Twin Astir

The Grob G103 Twin Astir is a German-built two-seat sailplane that became one of the most successful training and club gliders of the 1970s and 1980s. Designed by Burkhart Grob and first flown in 1976, the Twin Astir combined docile handling with respectable performance, making it ideal for ab-initio instruction and cross-country soaring. Its fiberglass construction and side-by-side seating offered a modern alternative to older tandem trainers, and more than 1,000 examples were produced before the line ended in the mid-1980s.

The type remains popular in North American gliding clubs for its forgiving stall characteristics and straightforward maintenance. With a best glide ratio around 1:34 and a minimum sink rate near 140 feet per minute, the Twin Astir is no record-breaker, but its reliability and two-seat versatility have kept many airframes flying decades after manufacture. The G103 has no engine and relies entirely on aerotow or winch launch, then thermal or ridge lift to stay aloft.

Its VNE of 135 knots and clean stall speed around 38 knots define a comfortable operating envelope for pilots transitioning from single-seat trainers or building cross-country experience. SkyMeter has tracked flights across airframes and operators, with the largest observed operator.