Boeing 737-700 Delta AirlinesDelta Airlines 737 airplane model. The 737 was conceived as a short range small capacity airliner to round out the Boeing jet airliner family beneath the 727, 720 and 707. Announced in February 1965, the 737 was originally envisioned as a 60 to 85 seater, although following consultation with launch customer Lufthansa, a 100 seat design was settled upon. Design features included two underwing mounted turbofans and 60% structural and systems commonality