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Making the Brazilian ATR-72 Spin
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Note: This story was corrected on August 10th at 10:23 am, thanks to the help of a sharp-eyed reader.
Making an ATR-72 Spin
I wasn’t in Brazil on Friday afternoon, but I saw the post on Twitter or X (or whatever you call it) showing a Brazil ATR-72, Voepass Airlines flight 2283, rotating in a spin as it plunged to the ground near Sao Paulo from its 17,000-foot cruising altitude. All 61 people aboard perished in the ensuing crash and fire. A timeline from FlightRadar 24 indicates that the fall only lasted about a minute, so the aircraft was clearly out of control. Industry research shows Loss of Control in Flight (LOCI) continues to be responsible for more fatalities worldwide than any other kind of aircraft accident.
The big question is why the crew lost control of this airplane. The ADS-B data from FlightRadar 24 does offer a couple of possible clues. The ATR’s speed declined during the descent rather than increased, which means the aircraft’s wing was probably stalled. The ATR’s airfoil had exceeded its critical angle of attack and lacked sufficient lift to remain airborne. Add to this the rotation observed, and the only answer is a spin.
Can a Large Airplane Spin?
The simple answer is yes. If you induce rotation to almost any aircraft while the wing is stalled, it can spin, even an aircraft as large as the ATR-72. By the way, the largest of the ATR models, the 600, weighs nearly 51,000 pounds.
Of course, investigators will ask why the ATR’s wing was stalled. It could have been related to a failed engine or ice on the wings or tailplane. (more…)
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How the FAA Let Remote Tower Technology Slip Right Through Its Fingers
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In June 2023, the FAA published a 167-page document outlining the agency’s desire to replace dozens of 40-year-old airport control towers with new environmentally friendly brick-and-mortar structures. These towers are, of course, where hundreds of air traffic controllers ply their trade … ensuring the aircraft within their local airspace are safely separated from each other during landing and takeoff.
The FAA’s report was part of President Biden’s Infrastructure Investment and Jobs Act enacted on November 15, 2021. That bill set aside a whopping $25 billion spread across five years to cover the cost of replacing those aging towers. The agency said it considered a number of alternatives about how to spend that $5 billion each year, rather than on brick and mortar buildings.
One alternative addressed only briefly before rejecting it was a relatively new concept called a Remote Tower, originally created by Saab in Europe in partnership with the Virginia-based VSATSLab Inc. The European technology giant has been successfully running Remote Towers in place of the traditional buildings in Europe for almost 10 years. One of Saab’s more well-known Remote Tower sites is at London City Airport. London also plans to create a virtual backup ATC facility at London Heathrow, the busiest airport in Europe.
A remote tower and its associated technology replace the traditional 60-70 foot glass domed control tower building you might see at your local airport, but it doesn’t eliminate any human air traffic controllers or their roles in keeping aircraft separated.
Max Trescott photo Inside a Remote Tower Operation
In place of a normal control tower building, the airport erects a small steel tower or even an 8-inch diameter pole perhaps 20-40 feet high, similar to a radio or cell phone tower. Dozens of high-definition cameras are attached to the new Remote Tower’s structure, each aimed at an arrival or departure path, as well as various ramps around the airport.
Using HD cameras, controllers can zoom in on any given point within the camera’s range, say an aircraft on final approach. The only way to accomplish that in a control tower today is if the controller picks up a pair of binoculars. The HD cameras also offer infrared capabilities to allow for better-than-human visuals, especially during bad weather or at night.
The next step in constructing a remote tower is locating the control room where the video feeds will terminate. Instead of the round glass room perched atop a standard control tower, imagine a semi-circular room located at ground level. Inside that room, the walls are lined with 14, 55-inch high-definition video screens hung next to each other with the wider portion of the screen running top to bottom.
After connecting the video feeds, the compression technology manages to consolidate 360 degrees of viewing area into a 220-degree spread across the video screens. That creates essentially the same view of the entire airport that a controller would normally see out the windows of the tower cab without the need to move their head more than 220 degrees. Another Remote Tower benefit is that each aircraft within visual range can be tagged with that aircraft’s tail number, just as it might if the controller were looking at a radar screen. (more…)
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Math Transports Jellyfish From Sea to Sky
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Technology rules the present and future of every aspect of aviation. It seems clear that pilots can’t fly today without it, or very well with it. If there’s handwriting on the hangar walls that pilots should be paying attention to it would be drone code, UAV, UAS, and RPA. But aviators are not alone. The technology geeks should check out “With Math as Inspiration, a New Form of Flyer” in the January 15 New York Times.
Dr. Leif Ristroph, an applied mathematician at New York University’s Courant Institute, created this small flying machine with four 3-inch wings. Electrically powered, it keeps itself right side up without sensors or a righting mechanism. Its stability depends completely on the shape and movement of its wings. And it is not alone. A variety of geometric shapes, a pyramid and section of a cone, float in a stable hover before the four-wing flying jelly fish flaps its way into the video that accompanies the article.
This captivating design is not a helicopter or some insect-derivative drone. Dr. Ristroph and his Courant Institute colleague, Stephen Childress, wanted to create a new form of hovering flyer. Why they wanted to create it is an unspoken question not answered in the article, but ultimately I guess it really isn’t that important. It’s also interesting that their design work that started with mathematics, which bring images of Sheldon’s formula-covered Big Bang whiteboards to mind.
Even more interesting is that the duo didn’t model their hovering jellyfish after the real thing. They made the connection after they turned their formulas and force diagrams into something tangible. Still, it makes sense because water and air are both fluids. I take comfort in the reality that while they solved the engineering side of the stability challenge, mathematically, “we don’t really understand for the active flyers how this works.” Nor do they know if their creation will be something useful, but for me, being captivatingly cool is enough. — Scott Spangler, Editor
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Flight Training, a GA Pilot and a Goose
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Taking a Bite Out of Those GA Accident Statistics
Whenever a flight instructor finishes up a training session with a GApilot — new or old — they always hope that pilot really understood the lesson before they head out on their own. An instructor knows that when an emergency arrives one day, there won’t be time for a last minute review. Just one more reason for all pilots to take some kind of regular flight training.
With GA accident numbers that never seem to decline, it’s nice to write about a pilot who did everything right … despite significant odds against him.
I spent some time chatting with private pilot Keith Baird the other day. He bases his 1968 Cessna 210 at Chicagoland’s Brookeridge Airpark, also known as LL22 southwest of the city. On December 28th, Baird decided to take a friend for an after-Christmas flight in some nice weather. But climbing through 400 feet or so on departure, Baird’s airplane collided with a 15-pound Canada goose, about the same size as the ones that downed a US Airways flight shortly after departure from LaGuardia five years back.
If you haven’t yet watched the short video shot from inside the airplane that day, it’s worth a few minutes of any pilot’s time. I’d never seen a video of a bird and a plane colliding through a windshield. Trust me it’s eye opening. Baird Bird Strike video. But come back for the rest of the story … (more…)