What does HUD display mean?

[Shane]

HUD is a head-up display system. The following are specific details about HUD: 1. Background: The head-up display, hereinafter referred to as HUD, is a flight assistance instrument used in aircraft. The term 'head-up' means that the pilot does not need to lower their head to see the important information they require. Head-up displays first appeared in military aircraft, reducing the frequency with which pilots needed to look down at instruments, avoiding interruptions in attention and loss of situational awareness. Due to the convenience of HUD and its ability to improve flight safety, civil aircraft have also followed suit in installing them. Cars have also begun to install them. 2. Principle: HUD uses the principle of optical reflection to project important flight-related information onto a piece of glass. This glass is located at the front of the cockpit, roughly at eye level with the pilot. The projected text and images are adjusted to a distance with an infinite focal length. When the pilot looks forward through the HUD, they can easily merge the external scene with the data displayed by the HUD. The purpose of HUD design is to allow pilots to maintain a head-up posture without needing to look down at instrument displays and data, reducing the rapid changes in the external environment that may be overlooked when looking down and up, as well as the delay and discomfort caused by the constant adjustment of eye focus.