Smartphones - a new flight safety instrument?

I was more than a little amazed to read that smartphones may become vital flight safety instruments, if a current NASA experiment bears fruit. Ares reports:

A lightweight automatic ground collision avoidance system (Auto GCAS) which depends on a terrain database of the entire world housed in a smart phone is being flight tested by NASA.

The flights follow initial development of the Auto GCAS for U.S. Air Force F-16, F-22 and F-35 fighters, and are aimed at extending use of the safety system to a much broader range of applications from unmanned air vehicles to general aviation aircraft. The system uses precise navigation, performance and digital terrain data to constantly monitor the aircraft’s position relative to known obstacles. Auto-GCAS is designed to intervene as a last resort, automatically recovering an aircraft when it senses that a ground collision is imminent and the pilot is not taking action.

Unlike the original Automatic Collision Avoidance Technology (ACAT) Auto GCAS project which was flight tested on an F-16D in 2010, this new test phase is using a 9 ft 8 inch wing span radio-controlled hobby Super Flyin’ King model aircraft [shown below - image courtesy of NASA].




Tests of the Droid (Dryden Remotely Operated Integrated Drone), are being undertaken by NASA Dryden Flight Research Center with support from the Office of the Undersecretary of Defense and the Air Force Flight Test Center.

“We’ve talked about the modular architecture which means you can put it on other aircraft, but we’d only flown it on an F-16. So we asked why not try it out on a very different aircraft,” says Auto-GCAS project manager Mark Skoog. Aside from demonstrating the transition and portability of Auto-GCAS to another platform, the project is also designed to develop and explore performance enhancements such as new escape maneuvers beyond the vertical fly-up used by the F-16 system.

New lateral escape maneuvers (marked in blue) are being tested
in the latest flight test phase (image courtesy of NASA)

Primary objectives include integrating the safety device without increasing the weight of the UAV, demonstrating a system that functions autonomously during a lost link with a ground station and showing the GCAS algorithm can be run using a smart phone – in this case a Motorola Droid X. The phone uses the open Android operating system architecture which can be modified to run the Dryden-developed Auto-GCAS software.

“We’re flying with the entire globe modeled on the phone. We can take it anywhere on the planet and it will have collision avoidance capability,” says Skoog. “This shows you can break the paradigm on accessibility to other platforms. You don’t have to go through a full-scale Defense Department development cycle, and it opens up many opportunities in the future,” he adds.

There's more at the link. You can read more about the original ACAT program here (link is to an Adobe Acrobat document in .PDF format).

The 'terrain database of the entire world' referred to in the article is that provided by the Space Shuttle, first using the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) during 1994, then in 2009 during mission STS-99, the Shuttle Radar Topography Mission. It's been enhanced by data from ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer), a Japanese instrument. Here are four examples of the depth of data obtained so far, visible in particular in the last two images, which combine photography and radar data on surface topography. Click on the link beneath each of the last three images to be taken to its NASA catalog page, from where you may view and/or download a much larger version if you wish. (Be warned - the image of North America is a VERY big file! Downloading it is very slow, even on a high-speed connection.)

First, here's an image from the 1994 SIR-C/X-SAR mission, showing Mount Pinatubo in the Philippines.




Over the next fifteen years, orbital radar and computer technology advanced dramatically, as can be seen in the following three images using data from the STS-99 mission of 2009.

Shaded Relief with Height as Color, North America

Cape Town, South Africa, Perspective View, Landsat Image over SRTM Elevation

Perspective with Landsat Overlay: Antelope Valley, California

As you can see, armed with elevation data so precise, plus navigation systems (inertial, GPS, or other) that can plot an aircraft's position in real time to within a few tens of yards, it becomes entirely feasible to build a terrain avoidance system that can direct the pilot (or take control of the aircraft itself) to avoid terrain obstacles ahead. I hadn't thought of loading it into a smartphone as an 'app', but of course, there's no reason why that can't work. A modern smartphone has more computing power than most desktop computers of five to ten years ago!

Here's a NASA video clip showing the ACAT system in operation on the test F-16D aircraft.

If the smartphone system can incorporate that sort of terrain avoidance information (albeit in a less automated form), it'll be a blessing to general aviation. Miss D. would have found it very useful during her epic journey from Alaska to Tennessee in a pre-World-War-II light aircraft earlier this year.

Peter