sentences:  In February 1961, the 171st Air Transport Group was formed at Greater Pittsburgh Airport flying the C-121 Constellation as a component of the Military Air Transport Service (MATS).Upon formation, the 147th Fighter-Interceptor Squadron was reassigned from the 112th FIG and re-designated as the 147th Air Transport Squadron, becoming the operational squadron of the new 171st ATG.The 146th FIS remained with the 112th FIG at Pittsburgh thus became the last Air Defense squadron in the PA Air National Guard.