The good, the bad, and the ugly of head-up displays.

Abstract

Issues with the head-up display (HUD) are wide and varied. The purpose of this article is to summarize and provide an overview of some of the pros and cons of using the HUD-to identify the good, the bad, and the ugly. HUDs have many excellent features, and the need for an HUD is well documented. Conclusion 1: there are many good things about using an HUD. However, work must continue to eliminate the bad. Most of the bad things described, if approached by human-factors engineers (given the authority to make the changes), could be corrected. Whether these corrections will be made is another story. Conclusion 2: most of the bad things can be corrected. The really dangerous features (the ugly ones) need to be addressed in the HUD education and training programs. Although the HUD training programs are not very common, flight instructors are becoming more aware of these more difficult issues. Perhaps these adjustments will be made as the HUD continues to evolve. Conclusion 3: HUDs have some problems that may not be fixed. It can be summarized, at least for now, that if HUDs are going to be used within the general aviation community, then caution must be exercised. General aviation pilots have the least instrument experience of all flyers, and the HUD is not intuitive-it requires training and continual practice. Except in a very few specific commercial aviation cases, the HUD has not lowered the weather minimums required to execute an approach. This should tell us something about the magnitude of its improvement to instrument flight. And there are a few reasons to be suspect of the HUD's safety, even in clear weather conditions. There are other head-down display concepts that could be tried (e.g., an outside-in display with a fixed runway, or a highway in the sky display) before the HUD is considered the final instrument solution to basic flight information for general aviation. The HUD has become a significant advancement of technology; however, it is not the end of flight displays. There are other solutions that must be tried and evaluated.