-
Making the Brazilian ATR-72 Spin
by
[sc name=”post_comments” ][/sc]
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…)
-
How the FAA Let Remote Tower Technology Slip Right Through Its Fingers
by
[sc name=”post_comments” ][/sc]
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…)
-
MCAS Certification a Human Factors Failure
by
[sc name=”post_comments” ][/sc]
During the interviews for a story on avionics interfaces, one source made a passing reference to interface failure of the Boeing 737 Max MCAS (Maneuver Characteristics Augmentation System). The significance of this observation did not resonate until I started reading FAA Advisory Circular 25.1302-1, Installed Systems and Equipment for Use by the Flightcrew, dated May 3, 2013.
The guidance in the 62-page AC “is intended to minimize the occurrence of design-related errors by the flightcrew and to enable the flightcrew to detect and manage errors that do occur.” I added the italics because the 737 Max interface certainly did not enable the crews of the two doomed 737’s to detect and deal with the MCAS errors. (And why the FAA conjoins flight and crew is beyond me, so I’ll separate them in the following sections of the AC.)
The AC addresses the design and approval on installed flight deck equipment and makes “recommendations for the design and evaluation of controls, displays, system behavior, and system integration, as well as design guidance for error management.” The complexity of the system design “from the flight crew’s perspective is an important factor that may also affect the means of compliance” with the certification requirements.
Part 25 requires manufacturers to design installed equipment whose behavior is “operationally relevant to the flight crew tasks…predictable and unambiguous.”
Operational relevance is the combined effect of the system’s operational logic, control function and placement, displayed information, and the crew’s perception and awareness of the system’s operation.
Complex controls that are inconsistent with each other or other systems are a source of errors. The family of controls includes buttons, switches, knobs, keyboards, keypads, cursor control devices, and touch screens.
After reading the guidance on “system behavior,” one wonders what obtuse rationalization laid the foundation for this aspect of MCAS certification.
Chapter 5 of the AC says a predictable and unambiguous system “enables qualified flight crews to know what the system is doing, and why. This means a flight crew should have enough information about what the system will do under foreseeable circumstances as a result of their action or a changing situation that they can operate the system safely.”
Clearly, this guidance did not lead to the desired safe outcome on two occasions. — Scott Spangler, Editor
-
Flying After Getting a New Hip or Knee
by
[sc name=”post_comments” ][/sc]
Needing to keep my mind occupied after they wheeled my wife into the shop to get a new hip, I wondered how joint replacement surgery would affect a pilot’s ability to fly. Thankfully, the surgical waiting room had wi-fi.
My only knowledge of orthopedic consequences to a pilot’s medical certification was Frank Tallman, the renowned movie pilot. In the mid-1960s, he fell while pushing his son’s go-cart and injured his knee. An infection set in, and the doctors had to amputate. Tallman got his medical certificate back with a Statement of Demonstrated Ability (SODA).
But was the the time-consuming process of getting a SODA necessary? A joint replacement returns a body to its original operating condition, fixing the problem that led to its replacement, like the pain involved with the arthritic corrosion.
Wandering through the halls of the FAA’s website led me to the Guide for Aviation Medical Examiners: Decision Considerations—Aerospace Medical Dispositions Item 42. Upper and Lower Extremities. First up was Amputations. Apparently nothing had changed since Tallman lost his leg in the mid-1960s. A SODA is still the solution.
In this table, there was nothing specific to joint replacement. Atrophy, neuralgia (and its related ailments), osteomyelitis, and “tremors, if sufficient to interfere with the performance of airman duties,” all required an FAA decision based on detailed reports specific to the condition.
The closest this table got, in the neuralgia entry, was “limitation of motion of a major joint…sufficient to interfere with the performance of airman duties.” Okay, but the doc said the new hip would (after she’d healed up) restore her full range of motion.
Hmmm. Google told me that docs replace approximately 700,00 knees and 400,000 hips every year. Certainly some of them had to be pilots.
Finally, in the Federal Air Surgeon’s Medical Bulletin, Vol. 48, No. 1 2010-1, I found information specific to hip and knee replacements. It was the last item in Dr. Warren S. Silberman’s “Certification Update: Information About Current Issues,” under the subhead: Orthopedic Surgical Procedures.
After talking about Herniated Nucleus Pulposus (spinal disk) and rotator cuff surgery, it said “The FAA allows all types of joint replacements,” which generally do not need a special issuance medical certification.
“We need to know why the joint was replaced and when the procedure was done (provide us the Operative report). When the treating physician and the airman feel he can return to flying, the FAA needs to know the range of motion and strength of the involved joint. It would be ideal if whoever generates this report addresses whether the airman can function in the aviation environment.”
And this won’t happen until the patient is off all of the industrial grade pain medications. I didn’t have to look up anything to know that a pilot taking an opioid does not fly. But, the doc said, my wife will be up and taking her first steps on her new hip as soon as the anesthetic wears off, so pilots getting a new hip or knee should know that their patch back to the cockpit starts there. — Scott Spangler, Editor