Takeoff and landing are the two most dangerous periods for any aircraft, a danger that is particularly intense for a helicopter caught in a brownout.
Caused by rapidly blowing sand and dirt thrown into a vortex by the rotor blades of a helicopter, a brownout's swirling dust gives pilots the illusion they are moving even if they are hovering stationary. Hazardous in any situation, it is particularly risky when landing in a combat zone.
"Flying in a brownout is very disorienting because you lose the visual cues that a pilot normally relies on to maintain a rate of closure and maintain aircraft attitude next to the ground," said Maj. Joe Minor, Chief of the Flight Projects Branch and Experimental Test Pilot at the Aeroflightdynamics Directorate at Moffett Field in California.
Having flown multiple missions in Afghanistan, Minor continues, "Traditional techniques involve trying to stay ahead of the brownout cloud to maintain visual contact until about 10 feet or so off the ground when the dust cloud envelops the aircraft. At that point you are committed to come down and forward until you hit the ground: if it's not performed precisely you can hit the ground too hard and cause aircraft damage," he said.
Currently an Office of the Secretary of Defense program is testing a Laser Detection And Ranging (LADAR) -based system called the Three-Dimensional Landing Zone (3D-LZ) at U.S. Army Yuma Proving Ground to give pilots a reliable pair of electronic eyes that can see in even the most degraded visibility conditions. Of particular importance to this testing was YPG's construction of the Degraded Visual Environment, or DVE, LZ, an isolated landing zone with tilled lanes meant to maximize the grit and dirt kicked up by a helicopter's rotor wash.
"It was custom-designed to test these technologies in brownout conditions," said James Savage, the Joint Capability Technology Demonstration's technical manager from Air Force Research Laboratory. "The sand and dirt is particularly powdery and silty, so you get massive plumes of dust that mimic the environments the pilots have been experiencing in theater."
Throughout the 27-month long program, experimental test pilots from the U.S. Army and Air Force fly tactically realistic scenarios across the proving ground's vast ranges, utilizing the DVE LZ and various mountain ranges along the way from YPG's Laguna Army Airfield. Both during the scenarios and in the training leading up to them, the pilots rely on LADAR information from the 3D-LZ's sensor projected onto an eight-inch screen that shows high-resolution 3D imagery of the terrain while highlighting obstacles in the path of the aircraft.
In addition to giving reports on their experiences using the system, the pilots are accompanied by a test observer and a chase helicopter that gathers data during each flight. The effort commonly requires the support of between 20 and 25 personnel.
In addition to such efforts as coordinating helicopter re-fueling at the isolated DVE LZ to maximize the testers' range time, YPG test officers ensure that the wide-ranging missions can take place without interference from other test programs in progress on the range.
"We work with other test officers to make sure that it is a seamless effort for our test team to share the range and YPG assets while, at the same time, allowing everyone to accomplish their mission," said Hi-Sing Silen Soto, test officer. "The task of scheduling and de-conflicting happens in the background: we try to keep ahead of the curve. This is a dynamic test with many moving parts, but that's what we do."
Testers hope 3D-LZ technologies will be fielded within several years, and they emphasize that YPG testing is an essential part of making it happen.
"It's been really good over the years," said Savage. "We get access to the range and all the people we need. Among all the places I test, this is first class."
"I enjoy testing here," added Minor. "YPG is a great place because a lot of smaller issues that normally occupy a test director are taken care of by the test officers here. You're allowed to focus on your test and getting your data without having to worry about minutiae."
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