Extra Eyes in the Sky
Advanced Tools for CFIT Avoidance
By James Williams
Source: FAA Safety Briefing Nov/Dec 2020
“With great power comes great responsibility.” You’ve probably heard that aphorism a few times over the past couple decades. The rise of superhero movies and series reboots over that time have hammered that witty point home. The line also resonates well with pilots because it does capture a certain raison d’être of flying. In a way what we do have is a real world superpower. A century ago, it was the preserve of only the most daring people, and a few decades earlier than that, it was literally impossible.
As with any hero, there must be a rogue’s gallery. In this issue we focus on controlled flight into terrain (CFIT). CFIT is a dangerous villain because it strikes often, even as it seems so obviously avoidable. Other articles in this issue cover various methods of CFIT avoidance, but I’m here to talk about using great powers.
X-Ray Vision
Who wouldn’t want X-ray vision? When I started flying a little more than two decades ago, I would have called you crazy if you told me I could have such capabilities in a general aviation (GA) airplane. But enhanced vision systems and synthetic vision systems (EVS and SVS) have made good on that promise.
EVS uses sensors like infrared cameras to “see” in different ways to include in the dark and through most weather. So EVS can help you avoid CFIT both at night and in poor weather. You need to be aware that EVS is not an EFVS (enhanced flight vision system). EFVS has specific hardware and display requirements in addition to training and currency requirements. EFVS allows a pilot to use the display information to proceed on an approach beyond the minimums. An EVS system can only be used to get you to a point where you must be able to see the runway environment with your own eyes. EVS thus lets you position yourself for the best possible chance to make the landing. It will let you “see” where to look for reference points that can be seen with the EVS system, before they can be seen by your natural vision, in addition to keeping you aware of your general surroundings and possible obstacles. Think of it like a traffic callout that helps you spot another aircraft, whether from Automatic Dependent Surveillance-Broadcast (ADS-B) systems or from ATC. By telling you where to look, it dramatically reduces the time needed to visually acquire reference points and improves your chances of seeing them.
Like most superpowers, though, this one has some limitations. First and foremost is cost. It’s a bit of a miracle to have EVS at all, but this particular miracle comes with a steep price. Second, EVS sensors have technical limitations. They “see” infrared wavelength which means they struggle to detect things like the LED lights that are becoming more popular on airports due to their high performance and improved efficiency. Part of that efficiency improvement is from dramatically reducing wasted heat energy as seen with other lighting forms. The problem for EVS is that waste energy is what the sensor “sees.” Some EVSs include multiple sensors that can detect LEDs, but this adaptation adds cost and complexity.
If your budget or hardware appetite doesn’t allow for EVS, there is another option: synthetic visions systems (SVS). SVS produce a similar end product — a depiction of the outside world sans weather and darkness — through an entirely different method. The synergy of highly accurate position detection, with high quality geographic data and increasingly common display screens, allows for the world to be “reverse engineered” around you by knowing exactly where you are and what geography and obstacles are in that area. This allows the SVS to “draw” a picture of the outside world regardless of conditions. In that way, it can have an advantage over the vision capability in some EVS, since those can be degraded in specific circumstances.
SVS can also be added to some avionics suites with far less expense and modification to the aircraft if you already have a compatible display and position information source. In fact, some manufacturers were able to add this function to existing devices in the aftermarket.
But as with EVS, SVS does have its limitations. Most critical is that what you see on the display is only as good as your position source and your database. Also, since SVS is showing you what should be there rather than what is there, it can’t display things like traffic, vehicles, or wildlife on the runway. So SVS should be used somewhat more strategically than EVS. SVS does allow for a major step forward in terms of CFIT avoidance that is much more accessible than an EVS, even if it isn’t quite as powerful.
Spidey Sense
While it doesn’t get as much attention in the most modern interpretations, your friendly neighborhood wall-crawler and web-spinner was known to be able to detect immediate danger headed his way. This spidey sense, as it was termed, proba-bly could be handy in an airplane. The same tools that help make SVS a reality can also provide extra terrain awareness and warnings. The concept has been around for a while in the form of Terrain Awareness Warning Systems (TAWS). TAWS, and its predecessor, the Ground Proximity Warning System (GPWS), were developed specifically to combat CFIT accidents in the air carrier world.
Early systems relied on radar-like sensors to detect ground and later used highly detailed terrain databases. These systems provided more warning time to the crew; they have thus been required in the air carrier world for decades. The rise of GPS as the staple navigation aid in GA, along with copious storage, meant that all the pieces were in place to make this superpower available to GA. These systems use the precise GPS location information combined with highly accurate terrain and obstacle databases and can provide aural and visual warning of impending danger depending on aircraft equipment configuration.
In the generic sense, TAWS capability is available from many avionics systems with the required components. Some systems can even be optioned with officially sanctioned TAWS. The difference between TAWS and the more generic systems is similar to that between EVS and EFVS. The certified TAWS system has to meet specific regulatory requirements in terms of equipment, installation, and data-base fidelity while the generic does not. The generic terrain systems can offer significant assistance to a pilot but do not meet the technical requirements of a certified TAWS. For the average GA user, though, even the basic terrain/obstacle avoidance technology is a huge win.
Just Another Rather Very Intelligent Assistant
No doubt you’ve seen movies featuring Robert Downey Jr. as Ironman, rapidly issuing commands to his AI assistant, Jarvis (an acronym for Just Another Rather Very Intelligent System), or later Friday, and thought it sure would be nice to have an assistant like that on my flights. Well, you might soon be in luck.
Like the competition for super-capable AI assistants in smartphones and home assistants, this idea is also gaining steam in the GA world. Research by the MITRE Corporation led to a software system called digital copilot, created to run on tablet type devices, which will give the pilot timely information and alerts. It works by monitoring a large set of aviation databases and flight progress. According to MITRE, “This prototype technology may be applied to airspace awareness, clearance conformance, approach briefing automation, surface safety, holding pattern depic-tion and traffic pattern entry, and other tasks.” MITRE’s goal wasn’t to bring an actual product to market, but rather to prove the concept and let others develop the idea.
That’s what has happened. Apps like ForeFlight and Garmin Pilot have added functionality to adopt some of the digital copilot concepts. These apps can do things like assist with preflight briefings and flight plans, provide notification of changing conditions on your route of flight, and pull up geographically relevant charts and procedures. As you would expect, there are differences between each implementation and some will be of greater benefit than others. All will improve over time as more experience leads to better systems. But the goal is clear: shift workload from the pilot to the digital copilot and provide another set of eyes to alert the pilot to potential problems.
Super Powers in Your Pocket
So you’re probably wondering where this leaves you if you don’t own or have a say in your airplane’s equipment. I have good news: you’re not left powerless. Some of the shiny new superpowers are available in portable devices. When combined with a portable ADS-B receiver/AHRS (Attitude and Heading Reference System) they can offer amazing capability. Some concepts like the digital copilot are designed for such devices while others can be adapted. In fact, with the addition of ADS-B/AHRS units, or if your aircraft has a compatible system, you can gain terrain/obstacle awareness and warnings and even SVS.
Yes, there are limitations. Much depends on the devices you have and how they play together. Not all providers offer their product on all mobile platforms. As with anything at the intersection of technology and aviation, you need to know before you go — check what works before relying on any of these superpowers.
You also need to consider inflight power usage. If the aircraft you are flying doesn’t have a way to provide contin-uous charging, it’s a good idea to have an alternative power source. Keeping the screen on, particularly at higher brightness settings, can drain the battery pretty quickly. The last thing you want is to line up for an approach and watch the approach plate disappear because your battery just died.
Notwithstanding the limitations, the portable revolution gives you a great set of tools for avoiding CFIT — tools that were unimaginable not so long ago. Most of these apps will allow free download at least for trial purposes. If you’re starting from scratch, make sure you have compatibility with all platforms and accessories you intend to use.
Check with friends and fellow pilots for advice on what to buy. You may be able to save a bit by opting for a slightly older model without sacrificing too much performance. You should also be sure to ask what accessories you will need. In terms of capability gained per dollar spent, these superpowers are some of the best deals in GA.
As stated earlier, great powers come with great responsibility. You have to know the limitations. Remember that most are for advisory use. It might be tempting to use that shiny new EVS to sneak below minimums on the approach. But that’s where the responsibility comes in. Pushing these powers too far could put you in exactly the situation they were intended to avoid.
James Williams is FAA Safety Briefing’s associate editor and photo editor. He is also a pilot and ground instructor. |
