Lift- and volume-dependent wave drag, induced drag and viscous drag are evaluated at key mission points. Inviscid drag is estimated using linearized methods. The viscous drag computation is sensitive to Reynolds number and Mach number, and is based on an experimentally derived fit. Special attention is paid to transonic drag rise, with numerous points being sampled up to and through Mach 1. Analysis detail is of a level that allows, for example, configuration tailoring to minimize drag during supersonic cruise (area rule).

Component weights are based on available data for various classes of aircraft. Wing weight is estimated based on a bending index that is related to the fully stressed bending weight of the wing box, coupled with a statistical correlation. Tail surfaces are similarly determined. Fuselage weight is based on gross fuselage wetted area and upon a pressure-bending load parameter.

CG location is computed based on typical placements for and weights of the various aircraft components; CG movement during the mission due to fuel burn is also computed based on the (user-definable) fuel tank layout.

Engines are typically modeled by sampling a manufacturer's deck at numerous Mach numbers and altitudes and constructing a fit. A number of sample decks are provided, emulating anything from a simple turbojet to a hypothetical propfan engine. Given the flexibilty of the software framework, it is possible to interrogate manufacturer's engine decks directly, though this incurs a hit in analysis speed.

Low-speed stability and trim are computed using a discrete-vortex method. This data is then used to predict such things as the BFL for the aircraft, stability derivatives and estimates for tail incidences at critical low-speed points (take-off rotation, for example).

The mission analysis routine ties together all the various tools in PASS to run an aircraft through a typical flight and evaluate its overall performance. The key points analyzed are the takeoff run, takeoff rotation, 2nd segment climb, subsonic climb to acceleration altitude, subsonic to supersonic acceleration, supersonic climb to initial cruise altitude, cruise and landing.

PASS provides a non-gradient based optimizer for configuration studies. Given some variables, the optimizer will minimize a given objective subject to constraints. The variables, constraints and objective are all user-defined. Typically, the optimizer will be tied to the mission analysis computation. Constraints usually consist of performance goals such as range and balanced field length. Additional constraints to ensure a viable aircraft in the eyes of the FAA may also be imposed, to ensure, for instance, that a conceptual twin-engined aircraft will climb out at the minimum 2.4% gradient stipulated by FAR regulations.