Software Proves Effective in Avoiding Aircraft Crashes

By Navy Lt. Jennifer Cragg
Special to American Forces Press Service

May 5, 2009 - Leading-edge software technology 25 years in the making by numerous Defense Department agencies and NASA has demonstrated a continuous 98 percent effectiveness rate of eliminating aircraft crashes, a NASA test flight director said. The primary development of the software technology began in 1984 by the Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio, and the Lockheed Martin aeronautical company, said Mark Skoog, test director for the Automatic Collision Avoidance System Fighter Risk Reduction Program at the NASA Dryden Flight Research Center. Skoog made the comments April 29 on Pentagon Web Radio's "Armed with Science: Research and Applications for the Modern Military."

"We based our test program off of mishap history of fighter aircraft at that time. We did an extensive study with Air Force Safety Center, out of Kirtland Air Force Base, to figure out what sort of mishaps we might be able to prevent with this collision avoidance system," Skoog said. "We found out that of all the mishaps that the F-16 had encountered, our system was able to prevent 98 percent of them."

The 98 percent effectiveness rating was gathered from an extensive evaluation of the F-16 system in 1998, he said.

Today, the program combines all of the subject-matter experts responsible for the technology under the same program so they can capture all of the knowledge that has been developed over the past 25 years and make it available to the aviation community, Skoog said.

ACAT systems sense collision threats, such as terrain or other aircraft, and activate an autopilot that can execute an avoidance maneuver. These systems were developed with three overarching requirements.

"Do no harm, do not interfere, and prevent collisions." he explained.

ACAT systems exhibit a high degree of control authority on the aircraft and use the aircraft's full maneuvering capability. Therefore, the biggest challenge is to ensure that ACAT systems operate "nuisance-free" in a way that does not interfere with the normal operations of the aircraft, Skoog said.

"Aircraft are already out there flying, conducting missions today," he said, "and we don't want to put a system on there that would inhibit them from accomplishing the mission."

In addition, ACAT developers aim to design a system that easily can be adapted to other military aircraft in the future.

"We're trying to create a modular software architecture -- somewhat of a plug-and-play capability for aircraft -- so that it can easily be adapted to other platforms and they can leverage the work that we're doing to the maximum extent possible," Skoog said.

Accompanying Skoog on the 13th "Armed with Science" audio webcast were David "Nils" Larsen from NASA, experienced pilot on both Air Force and Navy air frames, and retired Air Force pilot Kevin Prosser.

"We've got a system that we can field, and that's going to save lives," Prosser said. "We're really excited about that, and I look forward to doing some more flight tests with this program and hopefully getting out in the field soon."

Prosser has been flying fighter jets for more than 20 years. He flew F-15s operationally and did flight tests on the F-16 Fighting Falcon and F-22 Raptor.

"I was brand new in the F-16," he said. "I think my first high-risk flight test sortie with Mark, ... I had 70 hours in the F-16 at that time. So, [I was] a fairly experienced F-15 pilot, but inexperienced in the F-16. And, I found myself throwing my body at the ground and seeing if it will avoid the ground."

Larsen has been involved with testing for about a year and a half. Also a retired Air Force pilot, he flew U-2s, F-15s, and even did an exchange tour with the Navy, teaching at their test pilot school and flying F-18s.

"The potential for the future in preventing these collisions with the ground and collisions with other airplanes, that's some pretty neat stuff," Larsen said.

ACAT FRRP is part of a tri-party effort including the Office of the Secretary of Defense's Defense Safety Oversight Council, Air Force Research Laboratory, and NASA.

"We have a very broad team," Skoog said. "What has made this a success is the dedication of a lot of people at various organizations."

(Navy Lt. Jennifer Cragg serves in the Defense Media Activity's emerging media directorate.)