Which type of landing gear operations are executed with the tricycle-type landing gear?

The correct choice refers to the types of landing gear operations executed with tricycle-type landing gear, which encompasses both normal and emergency operations.

Tricycle-type landing gear is designed to provide stability during takeoff and landing. In normal operations, the aircraft relies on this configuration to ensure that the nose wheel remains aligned with the runway and to facilitate smooth landings. The design helps in preventing nose-over incidents, which are more common with tail-dragger configurations.

In emergency situations, tricycle landing gear systems are also essential. They must function correctly to allow the aircraft to perform safe landings under adverse conditions, such as when a tire blows out or if there's a necessity for a controlled landing due to systems failure. The emergency procedures typically involve specific checks and adjustments related to the landing gear to ensure the safety of the aircraft and its occupants.

Other options like manual and automatic refer to the modes of operation and not specifically to the emergency functionality. Likewise, standard and optional is more related to the variations of landing gear systems rather than the types of operations executed, and timed versus un-timed does not provide relevant operational context related to landing gear mechanisms specifically.