1. The aircraft model (Boeing 747-400) includes the basic equations of motion, aerodynamic model, engine model, auto-pilot, auto-throttle control system, aircraft sensors and air-data model. The aircraft model is based on point mass equations of motion but with additional realistic rotational dynamics about the centre of gravity (see [15] and [16]). The model includes lateral motion of the centre of gravity and dynamic characteristics of the engines [6]. A detailed description can be found in [16]. An admissible speed envelope model based on physical limits like stall speeds and maximum airframe speeds is incorporated in the aircraft model. These limits may not be as conservative as airline normal operational limits. B. Wind Model
2. The lead aircraft followed its own descent profile and a trail aircraft of the same type (Boeing 747-400 with initial mass 271 tonnes) adjusted its own speed to acquire and maintain desired time spacing behind the lead. The two aircraft were flying straight along different merging trajectories to the same fixed merge waypoint. Once the lead reached the waypoint each aircraft follows its own trajectory within the sequence, trail aircraft maintaining the spacingbetweenitselfand the lead, withbothaircraft descendingto 5,000 feet.
3. For each run the mean, standard deviation, maximum and minimum values of cumulative CAS speed variations were computed and recorded.Figure 10 summarizesthe resultsfor both manual and automatic modes.