The emergence of damage tolerance as a primary design consideration for new generations of aircraft is shown to be the result of concern for increased safety and reliability by airframe manufacturers and regulatory bodies. Design criteria applicable to the case of structurally damaged components are defined. Application of "failed single principal member" concept to typical airframe construction is found to have little effect on aeroelastic properties. Internal load paths for damaged structure are described, with typical examples of design practices aimed at minimizing structural vulnerability to damage.