Word has leaked that Google is planning to unveil some hardware later this year that will get pilots dreaming and developers drooling. Google’s sunglasses are designed to house a head-up display. The glasses, according to a report in the New York Times and on several tech websites, will cost several hundred dollars, feature Wi-Fi and cellular connectivity along with integral GPS and accelerometers. The HUD Glasses — Google hasn’t released any official information on the product — will run Google’s Android operating system and will integrate with Google Maps. Of course, the question that pilots are asking about these wired frame glasses is, “Could they be useful as a HUD for when we’re flying?”
Google isn’t even acknowledging the product, never mind talking about specific apps yet, so we reached out to those in the industry who develop HUDs for a living and asked them. While the promise of a wearable HUD is real, there are obstacles in developing aviation applications for the forthcoming Google product, they said.
According to technology experts from a major U.S. avionics manufacturer (which asked not to be named in this forward-looking story), for a HUD to be usable by a pilot in flight, “the projected image would need to be collimated, or focused close to infinity,” as traditional head-up displays are. The problem, according to the experts, with a close-focused HUD image is that the pilot will have to switch focus continuously between the HUD and the outside world, which invariably results in eye fatigue. Collimating the image, as is done on aviation HUDs to overcome this “is beyond the technology employed in the “Google HUD sunglasses,” the expert told Flying.
There’s another big obstacle that would prevent such a wearable HUD from being used for aviation purposes. In a fixed conventional aircraft HUD, the projected image is fixed in relationship to the view of the outside world, by being affixed to the cockpit ceiling. A wearable HUD would have to be “boresighted” with the aircraft electronically, so the HUD image would always be “dead-ahead with respect to the body frame of the aircraft regardless of head position.” This capability is also beyond the technology of consumer HUD technology.
Another hurdle is the quality of the display. For a HUD to be practical in flight, the projected image has to be very bright while also being sufficiently dimmable so that it’s useful in all lighting conditions from the very brightest “sun-in-the-eyes” days to “a moonless overcast night over unpopulated areas,” something that, again, is beyond the capability of a consumer HUD.
So, will there be any aviation apps for Google’s HUD glasses when they appear, likely later this year? Probably. They could include flight data, such as ground speed, track, GPS altitude and even moving map data. But it’s unlikely that first generation products (or second or third) will have the capabilities needed to give Google’s glasses any of the capabilities that make a dedicated aviation HUD such a powerful cockpit tool.
For more on this topic, read Robert Goyer’s take on HUD vs. combined vision.