Heads Up Displays - The next avionics disruption?

Head’s Up displays, aka HUDs, are a transparent glass that shows the airplane’s primary information overlaid on the pilot’s view outside the aircraft.?The information is presented in a green color since this is most sensitive to the eye. This technology was invented during WWII to help with targeting and was significantly improved through the late 1950s, then was standardized in the 1960s, and was used for instrument approaches in the 1970s.?Military aircraft, especially fighter jets and attack helicopters, use them since the pilots need to be focused outside the airplane during their dogfighting.?Commercial aircraft were slower to adopt the technology but most aircraft now come standard with HUDs, like the 787, or are going through upgrades via STC or TC Amendments.?

I'm not going to go into the details of HUD design, or the evolution of them from the beginning (combiner systems) to the much lighter versions of today (wave-guides). If you are interested then you should read the high-level, Flying article, https://www.flyingmag.com/how-it-works-head-up-display/.

So why am I writing about this technology in my blog??Well, HUDs are about to make a strong emergence in the business jet, GA and eVTOL markets.?There are multiple reasons for this, pilots can fly to lower minimums when using them, they make them better pilots, and their costs are decreasing.?According to a 2009 Flight Safety study (Paper), 'pilot error' accidents in take-off and landing could have been reduced by using a HUD by 69% and 57%, respectively. Keeping your eyes looking outside is better since keeping the aircraft level based on the ‘real’ horizon is better than looking down at the cockpit then outside and back-and-forth.?Your eyes must refocus each time they go from outside, infinite focus to an inside, close focus.??With the primary flight information overlaid on the outside 'picture', you can keep your eyes up and focused outside at all times. Now that the costs are coming down for this technology, the more that they will be in smaller aircraft.

In business aviation, HUDs are going to replace the need to have a Primary Flight Display (PFD) visible for the whole flight.?If you can use the HUD as primary (attitude, airspeed, altitude) then the PFD can be used as a map, synoptics, or other non-primary function.? The regulations state that your primary information must be within the pilot's primary field of view at all times. There is guidance in AC25-11b that states if you are using the HUD as a primary means of aviating then it must be certified as such. To take this a step further is to not require PFD when the HUD is in use.

The information that can be displayed on HUDs has increased over time with the current versions displaying infrared images, called “enhanced vision systems” (EVS).?When enhanced vision is combined with synthetic vision with the basic HUD content, this is called a combined vision system, CVS.?EVS is using the infrared spectrum to see heat signatures (non-LED runway lights, animals on the runway, terrain, etc) through light fog or night conditions. Having this visibility beyond your eyesight enables pilots to land in poor weather conditions.?For example, having an EVS on your HUD now enables an aircraft to land with cloud ceiling heights of 100 ft or to takeoff with zero visibility.?This allows aircraft to land at their primary airport more often instead of spending money burning fuel in a holding pattern, or worse diverting to an alternate airport.?Both scenarios can cost airlines thousands of dollars each time.

Secondly, HUDs have become wearable.?Wearable HUDs are goggles that present HUD symbology near to the eyes while the pilot's head is monitored and aligned with the airplane.?A pilot can wear these goggles during takeoff and landing or during times that an airplane-mounted HUD is used.?The wearable HUDs are less expensive, but not Google-glass cheap since they don’t require as much installation within the aircraft.?The installation is aircraft-specific by sensors located on the goggles that triangulate them versus the windscreen and the attitude of the aircraft.?Wearable HUDs have a bright future since they can be used in many more flight decks due to the less space that is required.

The last segment where HUDs have not penetrated is in low-end GA.?Arguably, this is where the HUD would be most valuable since the pilots are less experienced and can use all the help they can get to fly and land.?The challenge is there is less room in the cockpit, the price of the HUD is too high, and pilots are not ‘sold’ on the need.?An innovative company that is pursuing this market is MyGoFlight with the SkyDisplay. It has multiple STCs including on the Cirrus aircraft.?For under $30k (not installed), you can fly like a professional pilot, well almost since these HUDs cannot be used for landing credit. They are advisory only since they are not calibrated to the airplane or the pilot's line-of-sight, in other words, the real horizon is not calibrated to the pitch horizon of the HUD.

The suppliers of HUDs are growing. The following companies supply them into the commercial markets - Collins Aerospace, Thales, Elbit, Garmin, and MyGoFlight. Other suppliers that were or still are potentially working on civil HUDs are Saab and BAE Systems. Thales and Universal/Elbit have wearable HUDs. In my opinion, if you are a Tier 1 avionics company then a HUD is must-have in your portfolio.

When it comes to eVTOLs, imagination is the limit. Embraer Eve has released some great concepts of their vision of flight information. Just think how great it would be as a pilot to fly with this information below. This is a game-changer and should be part of the discussions on Simplified Vehicle Operations (SVO). There are some challenges with the windscreen now being a primary display, but hey, just details...

I'm excited for the next breakthrough in avionics and I would put HUDs in my top-3 that could disrupt the market. The other two would be SVO and open architecture (IMA) platforms...maybe I'll write about those in a future blog.