How is pitch control maintained in Back-up Mode?

In Back-up Mode, pitch control is primarily maintained through the use of pitch trim switches. This mode is typically engaged when the primary autopilot system or flight control systems are compromised, and manual control becomes limited. The pitch trim switches allow the pilot to make fine adjustments to the aircraft’s pitch attitude without needing to manually force the control yoke or stick. This is essential for maintaining the desired flight path and ensuring controlled flight under potentially challenging conditions.

Using pitch trim effectively allows the pilot to counteract any undesired pitch movements that might arise from factors such as airspeed changes or shifts in weight distribution. This capability enhances safety and stability during flight when other control systems are not functioning optimally.

In contrast, ailerons are primarily for roll control, not pitch control, making them less relevant in this scenario. Throttle adjustments influence altitude and speed but do not directly manage pitch attitude in the same way that trim does. The flight director, while useful for providing guidance, does not directly control the aircraft's pitch in Back-up Mode. Thus, pitch trim switches are the correct and most efficient means of maintaining pitch control under these specific circumstances.