Airweld Incorporated is the current STC holder and has FAA PMA for all of the original STC's issued to Winters, as well as STC's issued to subsequent manufactures including Kaiser Aerospace, WAPCO, and Advanced Aerospace. The On-Board Folding Airstairs can be found in use on many U.S. and Foreign Military and Government Aircraft including the Boeing E4B as well as VIP aircraft around the world. The On-Board Folding Airstairs is a multi-section (3, 4, or 5 segment) airstair that can be installed at either the forward, center, or aft doors.