Drones in our Airspace

Drones are here to stay. Not only are they here to stay, but it may surprise some who have not been following this topic closely to learn that the number of registered drones already far surpasses the number of registered GA, air taxi and commercial aircraft combined, and that gap is expected to grow dramatically in the coming decade. For example, based on FAA statistics, in 2017 the total number of registered aircraft in the general aviation fleet and air taxi fleet was 213,050 with an additional 7,141 commercial aircraft. Based on the FAA Aerospace Forecast Fiscal Year 2018-2038, numbers for general aviation, aircraft and air taxis are expected to hold steady for the next two decades while the number of aircraft in the U.S. commercial fleet is forecast to increase to 8,290.

By comparison, nearly a million drones had been registered with the FAA by the end of 2017. FAA forecasts approximately 2-3 million additional will be registered by 2022, and some experts believe that that forecast severely underestimates the coming wave of drones. Since manned aircraft and drones will be increasingly sharing airspace, irrespective of the type of certificate you hold, it's important that we all understand the rules of the airways for both manned and unmanned aircraft. The recently passed FAA reauthorization bill could also result in significant changes in rules for drones, including night flying and beyond visual line-of-sight flying, underscoring the need for a broad understanding of the rules for unmanned flight in the airspace we all share.

Before going any further, the terminology around "drones" can be confusing, so let's start with "what is a drone?" For our purposes, we're not talking about the military behemoths that we hear about in news reports, such as the MQ-9 Reaper with its 65-foot wingspan and 4900-pound empty weight. The regulation of these aircraft in U.S. airspace (known in FAA parlance as Large Unmanned Aerial Systems) is a different topic and outside the scope of this article. What we refer to here are "unmanned aircraft weighing less than 55 pounds on takeoff, including everything that is on board or otherwise attached to the aircraft." Such aircraft are referred to by the FAA as small unmanned aircraft. When referring to these small aircraft and all of their associated communications links and controllers, the FAA designation is small unmanned aircraft system (sUAS).

Although aircraft in the sUAS category can weigh up to 55 pounds, in practice, the vast majority of these drones weigh far less. The market leader here is DJI, and some of its most popular models weigh less than a pound (Spark), 1.6 pounds (Mavic Pro), about 3 pounds (Phantom 4 Pro) and 7.6 pounds (Inspire 2). However, it also offers drones that are listed as having a maximum take-off weight of just under the 55-pound maximum for this category. Other manufacturers, such as Yuneec and Parrot, have other offerings across the weight range, but the lighter-weight models are most prevalent. Drones weighing less than 250 g (0.55 lbs) do not need to be registered with the FAA and often have no capability for connecting to the internet. UAS weighing more than 55 pounds must be registered using the existing aircraft registration process (14 CFR part 47). The recent surge in popularity of drones is primarily rotary aircraft and can be quadcopters, hexacopters or octocopters.

However, there are many models of fixed-wing aircraft that fall under the sUAS designation that is used for both recreational and commercial purposes.

Pilots of manned aircraft need to know about where drones might be found in airspace and how they are regulated as part of standard risk assessment for any flight. However, the explosion in the numbers of registered drones, different categories of drone operators and recent changes in certification and regulation make a complete and up-to-date understanding challenging. In addition, as the numbers of drones increase, so does the probability of drone encounters, further underscoring the need for understanding how drone encounters comprise an aspect of risk assessment.

Drone flight is regulated by the type of drone, the use of the drone, the certification of the pilot operator, local airspace considerations and other factors, such as weather and time of day. As already described, drones in the sUAS category are those weighing 0.55 to 55 pounds. Aircraft is this category can be further divided into model and non-model. Most drones registered by the FAA in the recent past are characterized as model aircraft and are typically flown by hobbyists who require no certification from the FAA. The primary uses for model drones are for the simple joy of flying or for non-commercial photography or videography. Operators of model sUAS do not require a certificate from the FAA.

By comparison, non-model aircraft are those that are flown for commercial purposes and, for operation, a certificated pilot is required. The interesting thing about the distinction between model and non-model drones is that the same drones used by modelers are often high enough quality for commercial applications. For example, many commercial applications of drones simply require the ability to capture high-quality aerial images. These applications include real estate, roof and solar panel inspection or construction site monitoring. Example images are shown for each of those categories taken with the lightweight DJI Phantom 4 Pro. Other commercial applications such as professional cinematography and agricultural application require heavier drones capable of carrying a heavier payload.

Under current rules, there are two ways that sUAS can be flown legally, both of which require that the drone be registered with the FAA. Drones can legally be flown for hobby or recreation only without an FAA certificate by flying within visual line-of-sight, away from other aircraft, and by notifying any airport or air traffic control tower within five miles of the flight. Under normal circumstances, hobby flying cannot be done in Class B airspace. Hobby flyers are also expected to follow community-based safety guidelines and are prohibited from flying near emergency response efforts.

Drone operators can legally fly for recreational or commercial use by obtaining a Part 107 Remote Pilot Certificate. Like hobby flying, remote pilots flying under Part 107 must fly within visual line-of-sight, away from other aircraft, only in daytime or civil twilight with clear visibility at an altitude of less than 400 feet AGL. A big difference between hobby and Part 107 flight is that Part 107 pilots can operate in Class G airspace near airports without contacting the airport. Also, rules related to Part 107 are subject to waiver, which may permit flying at night or above 400 feet, for example. Flying under Part 107 allows operators to take advantage of the newly rolled out Low Altitude Authorization Notification Capability (LAANC) system, which provides a mechanism for flying in controlled airspace near airports using Airport Facility Maps, which specify altitude restrictions using a grid system superimposed upon the airport map. Finally, other restrictions for both hobby and Part 107 flight relate to flight in national parks, Special Use Airspace, near stadiums and sporting events, and near wildfires. Again, when operating under Part 107, waivers may be available for some of these activities depending on specifics. Commercial apps such as AirMap provide a graphical example of airspace limitations for hobby flying compared to Part 107 and Airport Facility maps; lists of airports currently participating in LAANC and related information can be obtained from the FAA website. (Note, there are other ways to fly a drone legally for commercial work, such as under what is known as a Section 333 Exemption, but these are largely being superseded by flight under Part 107.)

Now that we've described the type of drones that have been garnering so much publicity recently, where these drones can be flown legally and who flies them, let's return to the question of how much of a safety risk drones represent for manned flight and how to assess that risk. Obviously, the only real risk to manned aircraft of a drone is a collision, so what are some of the factors that could determine the likelihood and severity of a manned aircraft and a drone collision? Some that come to mind are altitude, weight and construction of the drone, type and construction of the manned aircraft and location of the impact on the manned aircraft airspeed. Under normal circumstances, with current regulations, drones will not normally be found above 400 feet AGL. On the other hand, fixed-wing manned aircraft will normally be below 400 feet AGL only shortly after takeoff and on short final approach for landing. Similarly, a large majority of drones are registered in the model category and so are likely to be on the lower end of the weight spectrum. These aircraft are limited in airspeed by regulation to 100 mph (87kts) but in practice, drone airspeeds in the range of 20-30 mph are probably more common.

For aircraft taking off and landing, the exact speeds vary by type of aircraft. In general, however, when thinking about the highest probability event for a collision between a drone and a manned aircraft, in aggregate these factors would suggest that the most likely event would be between a small drone and a much larger manned aircraft, both operating at relatively slow airspeeds. Current regulations for drone flight are designed to minimize drone manned aircraft "kinetic impact," taking exactly these factors into account. So would a drone versus conventional aircraft midair collision be catastrophic to the piloted aircraft? It's possible but highly unlikely.

It would seem, then, that even with an enormous increase in the numbers of drones in U.S. airspace, the risk of coming to harm due to a collision with a drone is exceedingly low. One additional factor, however, is that there are frequent reports of drone operators not following safety guidelines. Based on FAA sighting reports, there were just under 2000 instances where drone operations raised concerns from November of 2014 to June 2018. These included reports of drones operating dangerously in airport traffic patterns and instances where drones were operated far above the typical 400-foot AGL altitude restriction. Since a $1500 drone like the DJI Phantom 4 Pro (the one I own) has a service ceiling reported by the manufacturer of 19,685 feet, it may not be surprising to read in these sighting reports that drones were spotted at 8,000 feet. A drone being operated at 8000 feet, however, would not only be violating the 400-foot altitude limit. At that altitude, it's a certainty that the drone operator also would be violating the regulation for keeping the drone within visual line-of-sight.

As the pilot of a manned aircraft, then, how much concern should you have about drones? Probably the best way to think about it is by comparison to birds. It has been estimated that there are about 10 billion birds in U.S. airspace. Like most pilots, I've have had close encounters with birds comparable to the most common drones on many occasions and have never experienced a bird strike, nor have I lost a moment of sleep worrying about it. When there are birds on the runway or in the vicinity when getting ready to take off, our awareness of them as a risk is heightened. Likewise, if you are aware of drone operations nearby, heightened awareness about their operations is justified.

If drone collisions represent less of a risk than other risks we commonly treat as acceptable, as pilots of manned aircraft, why pay much attention to drones? One reason is that for anyone with a more traditional type of certificate, this is about the easiest add-on there is. It can also be a lot of fun, and you'll be able to provide your non-pilot friends details of why the breathless news reports about drone collisions are overblown. There are also many examples now of commercial activities that can be done more easily and cheaply with a drone than with manned aircraft. In fact, there are an increasing number of examples where drones are really the only practical solution, so increasing your understanding of drones improves your ability to assess the "right tool for the job."

Although employment prospects for manned aircraft pilots are bright and expected to continue so for decades, the FAA forecasts that over 300,000 new remote pilots may be needed in the next five years. Even for those who don't care to make being a remote pilot their primary source of income, commercial activities associated with sUAS could represent significant potential for extra income. Also, there are many worthwhile government and nonprofit groups who hunger for the expertise present in the manned pilot community. These range from model flying groups, such as local chapters of Academy of Model Aeronautics, to local airports and airport commissions struggling to understand their obligations relating to drone flight. In these communities your experience as a manned aircraft pilot is likely to be welcomed with open arms. In my case, I began flying drones after a local conservation group requested assistance setting up a drone program to augment its monitoring projects for coastal erosion and marine mammal protection. I never expected to be flying drones, but now that I'm doing it, I've added a whole new dimension to my flying that's fun and satisfying! Finally, there is already a huge group of drone pilots, and these numbers will only increase. Welcoming them into the aviation community generally can only help.