ATM Modernization, Commercial, Military

Q&A: Nick Sabatini and John Timmerman

By Charlotte Adams | September 1, 2005
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Like it or not, unmanned air vehicles (UAVs) are here to stay. The aircraft--big and small--have become a military fixture and made hundreds of flights in the national airspace system (NAS) this year. UAV manufacturers eagerly eye civil government and commercial applications to expand their business. So the pressure on FAA, with its total of about 8.5 "full-time equivalent" UAV people, is intense. Avionics Magazine recently visited Nick Sabatini, associate administrator for aviation safety, and John Timmerman, program manager for high-altitude redesign with the Air Traffic Organization (ATO). We discussed FAA's support of UAV integration at this transitional time, how the agency is handling the unmanned aircraft already crossing the NAS, and its vision for future operations.

Avionics: What priority does FAA give UAVs?

Sabatini: Here's where we place our highest priority. [He pointed to a wall chart depicting the accident rate for cargo and passenger carriers.] Detect, see and avoid, the foundation of our general operating rules to guide everyone who operates in the NAS--the rules of the road--today do not permit [routine UAV] operations.

We're stepping out aggressively with RTCA, a body that helps us establish standards in many areas. We're working [with RTCA] on command, control, communications and sense and avoid. Data link is part of it. I don't have a schedule for getting a rule. [But] I fully expect that within a two-year period I will have something [from RTCA] that is consensus-based, and we can then, with a good foundation, move forward into rulemaking activity. We can move as expeditiously as the rulemaking process allows to put those [recommendations] into regulatory form and promulgate them. Even though we end up with a comment period, I want to start the process on a well understood consensus basis, going forward.

Avionics: How serious is data link latency?

Sabatini: The technology is not up to the level to give us the assurance that we would have today with a manned aircraft. Because of that, we impose limitations on where [a UAV] can go and when it can do it. We're going to require redundancy that would prevent the loss of the [unmanned] aircraft. If one channel fails, is there a backup channel?

You're interested in how fast the FAA is going to be responsive to this industry? But we have a broader responsibility, not to the industry, but to the general public. You can appreciate the pressures that we face. We want to be responsive; we want to be enablers. But we need to do it responsibly and safely. And knowing the limitations, we're going to allow [UAV] operations under very controlled circumstances. And until we can develop an aircraft that, in fact, has no latency, and can handle all of these things [such as sense and avoid], only then will [UAVs] have perhaps the same access that other [manned] aircraft have. So the technology has to catch up with what they would like to do yet can't do today.

It's not FAA or the government that is the inhibitor. The inhibitor is the lack of technology to enable that which they are wanting to do in the NAS, when they are mixing it up with the entire fleet.

Avionics: FAA has requests for civil experimental airworthiness certificates [EACs]?

Sabatini: We have applications for seven types of UAVs. General Atomics for the Altair; Boeing/McDonnell Douglas for the Scan Eagle, two Bat-3s and a PMTD [Persistent Munition Technology Demonstrator]; Bell for Eagle Eye; the U.S. Special Operations Command for four Robinson R-22 Beta rotorcraft; and Northrop Grumman for a Hunter II. [The R-22s would be operated for research and development, transitioning to a supplemental type certificate once the proposed design has been proven out. The R-22 is a civil helicopter with an FAA type certificate.]

Avionics: What is an EAC?

Sabatini: An airframe today would be issued a type certificate that specifies everything about the aircraft--the design, performance parameters, what it is equipped with. It is issued in accordance with a standard that they demonstrate compliance with, for example the air transport category. Once Boeing, for example, demonstrates that they have complied with these rules that control the design of transport category airplanes, we issue a type certificate and, in conjunction with that, issue a standard airworthiness certificate.

There is no standard for UAVs. But we don't have a standard for home-builts and experimental aircraft either. These aircraft are great vehicles for people to do R&D. Under this EAC--under very controlled circumstances--we allow people to operate vehicles in certain airspace with limitations. For example, you can only stay in a given area. [An analogy is] the way we've been handling experimental aircraft for 50 years.

Timmerman: A lot of the safety wrappings that are in COAs--such as coordinating with air traffic--you'll see embedded in EACs. [COAs, which FAA awards to military or government applicants, are certificates of waiver and authorization.]

Avionics: Who's working on issues such as wake turbulence?

Sabatini: Today we have gliders--tiny little things--and we're about to launch the A380, a freighter version of which takes off at 1,300,000 pounds [589,700 kg]. We don't say, the design of your airplane looks kind of flimsy or it's too heavy. What we say is, you must demonstrate that you can control that aircraft through design, so whether it's the glider encountering crosswinds or turbulence, it must be designed to handle the conditions under which it's going to be certified to operate in...individually, each one.

As far as wake turbulence is concerned, we have separation standards today.

Avonics: Do you use the same separation standards?

Timmerman: We use the same separation standards. But we always anticipate what we need to do to maintain those standards. With a UAV we anticipate it takes a little bit more effort to [meet] the standard. Maybe by issuing a clearance sooner.

The operations we have today, unlike file and fly, all take a little bit of extra coordination, so the controllers are specifically briefed on those flights about unique characteristics. We put people in there to coordinate procedures in case they lose link. There is a lot of extra special stuff done for [UAVs].

We make sure that we're going to have enough room around them [and] that they're not going to cause a problem with latency. But we do not segregate or restrict the other airplanes from operating in the NAS just because of unmanned aircraft.

Avionics: Can you apply the standards of manned aircraft to unmanned aircraft?

Sabatini: Why not? Let's fast forward to a time when we have complete technology capability, and we have a UAV following an A380. Of course, we would separate that vehicle, the same as we would someone following a B747 today. They're going to have to demonstrate that they can operate in an area...with an equivalent level of safety.

Timmerman: We have different standards for sizes of aircraft. It's the same with UAVs. When they get certificated, [FAA] will give us standards: this is how many miles behind this airplane has to fly.

Avionics: How do you define an equivalent level of safety?

Sabatini: The equivalent level of safety means--given those limitations and controls they put in place--there's no difference between the operation of that [unmanned] aircraft and the operation of a manned aircraft.

We put that responsibility on the operator. With a UAV it is incumbent on that applicant to describe to us how they are planning to assure that they are not going to run into other aircraft. They need to demonstrate that. Since they can't really demonstrate that with the kind of precision that we need, we will say...the aircraft cannot be operated outside of your line of sight, which really limits their distance. Or if it's going to operate beyond line of sight, it probably is going to involve...others along the line who would have line of sight control over it. If that is not possible, probably they [a military applicant] will have to demonstrate that they have the ability to use a chase airplane. And the purpose of a chase airplane is to make sure that, if the UAV starts to go astray...they may have to shoot it down.

So it's up to them to come to us with a plan that gives us assurance because they've done the risk analysis and the probabilities of these things happening. We would then...develop a set of limitations that compensate for that.

Avionics: Are you going to apply 10-9 reliability?

Sabatini: 10-9 means we don't have a single-point failure, that you have redundancy. What systems do we need to build in the aircraft so that a single failure doesn't cause a catastrophic event? We have to learn from the use of UAVs.

Is it possible that cargo carriers could conceivably be operating a 380, 747 and 777 as unmanned vehicles? Why wouldn't they want 10-9 for something like that? Let's get out of the notion of the Predator and the little Firefly.

Avionics: What about guidance as to climb speeds, turn speeds?

Sabatini: We do not today impose on a manufacturer how fast an airplane has to be able to roll in order to turn or how fast it needs to climb. The value of the air traffic system is that they separate different capability and different performance. Our rules will not specify what you must be able to turn at, climb or speed.

What we do say, for example, in the design criteria for manned vehicles is, once you're up and flying, you must provide clear notice...that you're approaching a stall. On a UAV do we have to warn the operator on the ground it's getting too slow or that it's exceeding its maximum forward speed? Those speeds, that envelope, is determined by the designer in terms of what the mission profile is.

We would like to say something like--on the airframe side of it--if you get too slow, there's got to be some sort of adequate warning to the operator who's on the ground...other than just watching the airspeed indicator...because when you exceed these limitations, things can happen that could cause it to become uncontrollable.

Avionics: Give me an example.

Sabatini: It depends on what they ask for, the authorization to conduct a particular operation. We evaluate that and make a determination as to how best to protect people in the NAS and people on the ground. [Applicants] have to demonstrate that they can control this device, either through line of sight, chase aircraft or data link.

Today we don't have the kind of redundancy we're looking for. We put the responsibility of the hazard analysis on the people who are requesting the authorization. In the event you had a total loss of communication, for example, how would you deal with that? They need to answer that question to our satisfaction. We expect that they describe that in great detail, so that we have a level of confidence in their ability.

Avionics: How are you handling military vehicles today?

Sabatini: COAs have been in place for some time. They would apply to any government agency, including FAA. [The military] can decide for themselves what a fighter needs to do, how it needs to be built and how it flies. But [in the NAS] they are comply with the operating rules of FAR Part 91. The military doesn't have to tell us when they're going to operate [manned aircraft] in the NAS if they're not going to file an IFR [instrument flight rules] flight plan. Just like anybody else, they can choose to do that and they'd be perfectly legal.

But when you identify it as a UAV, they can't just choose to operate in that same airspace...without us authorizing them to do that under very controlled circumstances that we specify in a COA. There are very specific limitations as to where they can do it, when they can do it, how they can do it, etc., that would give us the confidence in the capability of a UAV to operate autonomously, as we would expect a manned vehicle. The technology is not there yet. And when you consider that a pilot sitting in an aircraft has kinesthetic as well as vestibular sensory [inputs] working on his or her behalf, anything the aircraft does that human knows about. [A UAV] can't separate itself [from other traffic] the way a pilot can.

Avionics: UAVs have had a high accident rate.

Sabatini: Where the accident rate is high, we're in what we call fix and fly. You have a crash, find out what happened, fix it, fly it again. It breaks, you fix it and fly again. We don't want to be there, but we are there today. That's part of the growth that's going to take place with any new technology.

Timmerman: The thing we do with unmanned aircraft, even in COAs--which is a similar procedure to the [manned] experimentals--is have lost link procedures. These are procedures worked out with the manufacturers to [have the UAV] return to base or go to some place and orbit and try to pick up the link. They have ways to get in with multiple paths. Sometimes they may be controlled by satellite. They go back to their home base and do a direct line of sight link. So there are procedures built in.

Timmerman: Some of the larger UAVs would take off in restricted military airspace and climb up to Class A airspace [above 18,000 feet mean sea level]. While they were in Class A...we provide separation. But when you're below Class A, you're mixing it up with VFR [visual flight rules] aircraft. That's where see and avoid really comes into high focus. We just don't let them fly in that airspace unless we provide a chase plane or an observer around them.

Avionics: Have there been hundreds of UAV flights in the NAS this year?

Timmerman: If you look at the whole variety of them, that's probably true.

Avionics: Do you keep count?

Timmerman: We don't maintain a count. We don't put [flights] into a big database and manage it. There's administrative overhead in knowing that. We've been more focused on supporting the operation than just counting them.

Avionics: Some COAs allow a year's worth of flying?

Timmerman: That's correct. Each COA has provisions to operate. Some COAs don't even actively involve air traffic control. They're just flying very low altitude close to the base. Some COAs require previous coordination. For example, if Global Hawk's going to take off, we need to know about it in advance and coordinate it. Each COA is tailored to the specific operation they want to do. We put provisions in those COAs to make sure there is safety to the public and other operators in the NAS.

Avionics: How many COAs have been issued this year?

Timmerman: A little over 20. Four or five are pending.

Avionics: Is the idea of first dealing with small UAVs off the table?

Sabatini: Not off the table. But we have to be responsible for the safe introduction of these vehicles on a large scale without needing EACs or special limitations. We have to define what those conditions are and make them standard and available in a regulatory framework. That is being developed with the help of RTCA.

Avionics: What about model aircraft?

Sabatini: We're going to very quickly look at the current advisory circular [AC] that addresses model aircraft. We're going to explain with great clarity what a model airplane is and where you can operate it. It's not going to be a 300-pound device. The context is going to be brought into 2005 and future thinking...stay at very low altitudes, and [don't] operate over a congested area. We probably would stick with the same altitude [400 feet]. We hope to get it out in early 2006.

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