Mission Performance Aids discern all mission critical events: detect all signals, categorize all mission critical events according to their intrinsic risk producing properties, alert the crew to the detection of all mission critical events, and formulate and display appropriate responses to all such events. Most importantly, they know how to respond to mission critical events described as extremely dangerous.
All Mission Performance Aids (MPA) are conceptualized and derived from the previously presented mission performance models. This reference to an appropriate mission performance model is important to not only ensure all performance aid requirements are met but as a means to avoid piecemeal and largely ineffective design initiatives. These models have been organized under the following categories:
The basic concept of MPA is discussed in this chapter. Utilizing the appropriate mission performance model as a template, a mission performance aid is an information package that is automatically displayed to the flight crew (flight deck) during changing operational conditions. This built-in capability provides the flight crew with the right information at the right time. The time-sensitive MPA is triggered by encountering a mission critical event. Mission critical events are categorized using criteria such as levels of danger. Here is a brief overview of a crew station MPA display protocol.
Trajectory Management
Performance aids are most useful when the time between a mission critical event and an appropriate response to the event is short. The most important aspect of an operationally useful performance aid is the depiction of target pitch attitudes. A target pitch attitude is a per-determined trajectory control parameter that is specified for a number of specific maneuvers. Operating within this control parameter is essential for mission success.
A target pitch attitude the initial attitude to get the airplane on the proper trajectory. After the target pitch attitude is achieved, it may be necessary to continue to optimize the trajectory. These refinements may often include the use of the flight director, vertical speed indicator, and aircraft heading. On the crew station’s attitude directional indicator, the pitch attitude ladder is segmented into 2.5 degree intervals. These are explained below.
The 20 degree pitch target: reserved for only one maneuver, the ground proximity statement or escape maneuver. This maneuver involves the immediate execution and achievement of the specified pitch attitude to avoid catastrophe.
The 15 degree pitch target: target pitch attitude of takeoff when anticipating wind shear or any other need to abandon normal noise abatement profile. This is also the attitude of a normal missed approach and wind shear recovery during the landing maneuver.
The 12.5 degree pitch target: for an engine failure during takeoff operations for most narrow-body transport airplanes. A narrow-body transport airplane is one in which the maximum takeoff weight does not exceed 250,000 pounds. This is also the target pitch for a missed approach.
The 11.5 degree pitch target: for an engine failure during takeoff operations for most wide-body aircraft except for the Boeing 777. This is a lower pitch attitude than for the narrow-body fleet is because of different flap and wing design.
The 10 degree pitch target: for an engine failure during takeoff operations, engine failure on missed approach, and engine out missed approach for the Boeing 777 and other similar airplanes.
The 5 degree pitch target: for engine out ILS approaches.
The 2 1/2 degree pitch target: for normal ILS approaches for most aircraft and ILS approaches for wide-body heavy aircraft operating either one or two engines.