Wednesday, June 16, 2010

Send in the Drones?

There can be no doubt that we are being prepared for the day, not very far off, when we will be sharing the skies with Unmanned Aircraft Systems (UAS), also known as drones or remotely piloted vehicles (RPV's). According to a recent Associated Press article, the FAA is coming under heavy political pressure to admit UAS's to the national airspace:
Texas officials, including Gov. Rick Perry, Sens. Kay Bailey Hutchison and John Cornyn, and Rep. Henry Cuellar, have been leaning on the FAA to approve requests to use unmanned aircraft along the Texas-Mexico border. ...

Homeland Security Secretary Janet Napolitano has told lawmakers that safety concerns are behind the delays. Cornyn is blocking a Senate confirmation vote on President Barack Obama's nominee for the No. 2 FAA job, Michael Huerta, to keep the pressure on.

Other lawmakers want an overall plan to speed up use of the planes beyond the border.

There are, to put it mildly, safety concerns. In the same article, the FAA's head of air traffic operations, Hank Krakowski, is quoted as saying:

I think industry and some of the operators are frustrated that we're not moving fast enough, but safety is first. This isn't Afghanistan. This isn't Iraq. This is a part of the world that has a lot of light airplanes flying around, a lot of business jets."

In April 2008 the National Transportation Safety Board held a 2-day Unmanned Aircraft Systems Safety Forum discussing the safety issues surrounding integration of UAS's into the national airspace. The forum was organized in the aftermath of a mishap two years earlier when an RPV operating in civil airspace suffered the loss of both power and communication due to operator mis-management and subsequently crashed. The NTSB Final Report reads like one of those "nothing can go wrong...go wrong...go wrong..." scenarios.

Of course, the FAA is reacting to the pressure. Now comes the May/June 2010 issue of the publication FAA Safety Briefing, offering on page 20 an article titled "Eye in the Sky." The subtitle is "Assuring the Safe Operation of Unmanned Aircraft Systems." The article observes that:

[D]espite the numerous environmental, economic, and safety benefits of UAS, there remains an underlying, and understandable, apprehension of how these “flying robots” will perform alongside manned aircraft, especially during an unexpected event or emergency.

In discussing this apprehension, the article reviews ongoing FAA research regarding the characteristics and behaviors of UAS's, and acknowledges the need to address the "sense-and-avoid" (sic) issue.

Of course, the "sense-and-avoid" issue (which used to be called "see-and-avoid") is the elephant in the room. Here's what an executive of Insitu, Inc. (a Boeing subsidiary in the UAS business) has to say:

While we don’t have a pair of eyeballs on the aircraft, there are several feasible alternatives that need to be tested and evaluated.” Existing test data show current ground-based radar and TCAS systems are able to pick up nearly any vehicle within 12 to 15 miles of a UAS. “By working with the FAA, we’re seeking to obtain the safety ‘street’ credit for these systems, along with rules that permit reasonable access.”

Isn't that nice. We will supplement the UAS's on-board sensor suite with radar data (and, no doubt, ADS-B Out product - another reason to press on with NextGen) so that the robot can "sense-and-avoid" threat platforms. It is unclear how that is going to help the VFR pilot in the Cessna 172 who is squawking 1200 and not talking to ATC to understand that he is potentially in conflict with an aircraft that has only a limited ability to react to his presence. And that doesn't begin to account for the NORDO J-3 Cub or the sailplane or the hot air balloon, any of which may or may not be "sense-able" by the UAS's "sense-and-avoid" systems.

As if "see-and-avoid" were not already sufficiently problematic as a collision avoidance strategy (see, for example, the circumstances surrounding the mid-air over the Hudson in the summer of 2009) we would now shift most of the burden of "seeing-and-avoiding" to the general aviation pilot with the degree of difficulty increased by the typically small size of the UAS.

A few conclusions can be drawn. First, it is apparent that there are political and economic forces in place that are strong enough to ensure that This Will Happen. UAS's are coming to an airspace near you.

Second, it would seem that the only way to accommodate UAS's in the National Airspace System without unacceptable risk is to understand that any airspace in which they operate is de facto Restricted Airspace. As with the Restricted Areas that we're already familiar with, IFR traffic can be separated from UAS operations by ATC; VFR traffic will have to avoid the airspace. Check NOTAM's!

The alternative would be to require UAS's operating in unrestricted airspace to carry Visibility Enhancement Systems to give pilots a fighting chance to see them and avoid them.

  • Light 'em up like a Christmas tree!
  • A colored smoke trail would be nice.
  • While we're at it, restrict them to 140 knots.

Of course, that would eliminate any thought about stealth. The border patrol probably won't like that.

The FAA is planning to publish a Special Federal Aviation Regulation (SFAR) that will govern operation of small (under 55 lb.) UAS's in commercial airspace, by mid-2011 with a final rule
expected in late 2012. That one will bear watching.

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