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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.
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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21st Century Airship Development Preserves History
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The most fascinating nugget of news in the announcement of the FAA’s issuance of special airworthiness certificate to Pathfinder 1, LTA’s prototype 21st century rigid airship, is the authorization to fly it in Class D airspace defined by California’s Moffett Federal Field (NUQ) and Palo Alto Airport (PAO), which is next door, so to speak. The nugget was nestled in LTA’s certificate application. The airship’s experimental flight test program would establish its flight envelope through “substantial indoor and outdoor ground testing.”
I emphasized indoor because rigid airships are not small flying machines. Pathfinder is 124.5 meters of carbon-fiber-polymer tubes connected by titanium hubs. You need some pretty good indoor space to fly something 136 feet long. Fortunately, LTA Research, founded by Google cofounder Sergey Brin, has options. And in acquiring them, he has saved significant parts of American lighter than air history and national historic landmarks that continue to make contributions to aviation, and would be nearly impossible to replace or recreate.
Moffett Field is south of San Francisco, established in 1931 as the Navy’s West Coast rigid airship facility. (Lakehurst, New Jersey, served America’s sunrise coast.) It is home to three airship hangars. The Navy built Hangar 1 in 1933 for the USS Macon, ARS-5. In 2011, Google’s founders saved Hangar 1 from demolition by underwriting its restoration. Three years later, Google subsidiary Planetary Ventures signed a 60-year lease with the General Services Administration to manage Hangar 1 and the surrounding airfield.
Across the main runways from Hangar 1 are the smaller Hangars 2 and 3, two of the world’s largest freestanding structures. They are two of the 17 wood blimp hangars the Navy built during World War II for its antisubmarine blimp fleet. Hangars 2 and 3 are two of the seven survivors (there are two more in Tustin, California, two at Lakehurst, New Jersey, and one at Tillamook, Oregon). Pathfinder 1 made its first flight inside Moffett’s Hangar 2 on May 12, 2023.
After Pathfinder 1 finishes if Moffett Field flights, it will move to Akron, Ohio, home of the 1175-by-325-foot Akron Airdock, which LTA bought in 2022. Once the world’s largest structure without internal supports (it covers 364,000-square-feet, roughly 7 football fields), the Goodyear Zeppelin Corporation built it in 1929. From it emerged the US Navy dirigibles Akron, ARS-4, in 1931, and the Macon, ARS-5, in 1934.
Pathfinder 1 is but a prototype, to be followed by larger iterations as the test program progresses. And, in time, it will offer aviation aficionados the unique opportunity to witness the past, present, and future of one (lighter than air) aspect of aviation. — Scott Spangler, editor