Hiding in Plane Sight

       No I am not going to apologize for that cheap pun.

     Currently all passengers must wear masks both on airplanes and in airports. Positively identifying every passenger is at the heart of aviation security. Without effective positive identification it is fairly easy for a person to steal and use the identity of a someone else to board a plane. This way a person with a concerning or criminal background faces fewer obstacles to overcome. Every gap in this layer of security broadens the number of people who might try to pass airport security for nefarious purposes. Masks present a small chink in the positive identification armor.

      Currently, the only place a person must remove their mask for identification is the entry to security. While this single identity checkpoint has always been the norm, a single, tired, agent on a busy day might make a mistake or not examine a face closely enough. A person wearing a mask at an airport used to attract a bit more scrutiny from employees, now that it is the norm, this small indicator is now gone. 

     Not requiring masks (or requiring clear masks, gross) is the most obvious solution to this problem. However, this is unlikely to happen any time soon. But even without masks there is still the problem that positive identification is only done at one point by one person. Boarding the airplane must be a second point of identification. When dealing with any sort of checks or security relying on a human factor, two person integrity is necessary.

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(n.d.). Retrieved December 29, 2020, from https://www.tsa.gov/

Security Guidelines for General Aviation Airport Operators and Users. 
     (2017, July). Retrieved December 29, 2020, from      
     https://www.tsa.gov/sites/default/files/2017_ga_security_guidelines.pdf

Blog 3.2 Air Data

 The Lockheed C-130 Hercules, uses a pitot static system to collect air data. The information from this system is used to determine barometric altitude, airspeed, and vertical speed. The pitot tubes measure ram air from the relative wind and the static ports measure the ambient air pressure.

Pitot tubes with and without covers. Covers prevent damage and FOD from entering on the ground.

Static port for measuring ambient air pressure.

     There are two separate, identical, and redundant systems, each one feeds to its own air data computer and then to the pilot or the co-pilot. On the C-130 J model the first indication of a problem with any system is usually the Alerts, Cautions, and Warning System (ACAWS) announcement. This may include an audible signal as well as a digital phrase stating the problem on one of the pilot's screens.

ACAWS messages area.

      One problem which may arise is an airspeed split. When the pilot and co-pilot's tachometers show different air speeds. This can be cause by a blockage of a pitot tube, usually by ice, a malfunction in the air data computer, or a leak in the air data system among other potential problems.

A Pitot-Static tube similar to the C-130. Note the static holes on the tube itself.

     Without accurate air data the pilots will be unable to make safe decisions regarding stall speeds, landing and takeoff speeds and overspeed limits for various airplane configurations. Further it is unsafe to assume that the broken system is the slow system as many aircraft systems, especially the C-130 are computer controlled and so the cause of the problem may not be deduced in flight.

Druck brand test set. This machine produces pressure and vacuum to simulate flight.

    If this occurs in flight it is best to use the "slower" altimeter for all slow speed and stall speed limits and to use the "faster" altimeter for all overspeed limits. Once on the ground the issue will need to be immediately addressed. This involves setting up an air data test set hooked up to the pitot tubes and static ports and simulates an aircraft in flight. Using this data the system the maintainers can then troubleshoot to determine the faulty component.

This fitting goes over the pitot tube. Hoses run from it to the test set.

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ERAUSpecialVFR. (2017, August 01). Pitot-Static Instruments. Retrieved December 19, 2020, from                    https://www.youtube.com/watch?v=kdFGbUouE_4

United States, Coast Guard. (n.d.). Flight Manual C-130 J USCG Series Aircraft.

Clear icing: An brief explanation of how it forms, why water does not always freeze at 0 degrees Celsius, and the adverse effect on clear ice accumulation on the aerodynamic capabilities of an aircraft.

     I had a simple question. How does supercooled droplets of water exist? How does water not freeze at 0 C? I did my research and this is what I found. “We also determined the number of water molecules N* in the critical ice nuclei (including their sheath of intermediate-ice) through the mean first passage time (MFPT) method.” (Moore, 2011) Not surprisingly, this is one of the easier sentences to understand.

    Pure water does not freeze at 0C. It needs a nucleus to form a crystal around. According to Smithsonian magazine (which helpfully summarized the Moore Nature entry) water will not spontaneously form a nucleus until -40 degrees. (Zielinski, 2011). When this supercooled water contacts the aircraft it instantly freezes into clear ice, having a non-water material to catalyze the crystallization process. This icing is most common at temperatures between 0 and 15 degrees Celsius. (“Pilot’s,” 2016) Supercooled droplets of very pure water are found in the low part of turbulent cloud systems. (Airboyd, 2010)

    When clear ice forms on the various forward surfaces it will cause a variety of detrimental effects. Blockage of intakes and carburetors will restrict airflow, and ice on pitot tubes will cause improper reading of airspeed. But most critically the aerodynamics of the vehicle itself will be negatively changed. It is not the weight of the ice, but the shape which is the concern. Clear ice builds up around the aerodynamic surfaces, thickening and deforming the shaped of the airfoil. This significantly reduces the lift capability of both propellers and the leading edges of wings.  (Airboyd, 2010)

     The two primary ways to counteract any icing on the leading edge of an airfoil are using a deicing boot or electricity. A deicing boot is inflated by drawing bleed air off of the engine, that is air that is is taken from the compression cycle of the turbine engine. Alternatively a deicing boot can be inflated using an engine driven pneumatic pump. Propeller blades are deiced with electrical heaters which run along the leading edge of the blade. (Pilot's, 2016)

I think that is pretty a pretty cool fact.

Airboyd. (2010, January 22). Ice Formation On Aircraft (1960). Retrieved December 11, 2020, from https://www.youtube.com/watch?v=9I40DQcK_6U

Moore, E. B., & Molinero, V. (2011). Structural transformation in supercooled water controls the crystallization rate of ice. Nature, 479(7374), 506-8. http://ezproxy.libproxy.db.erau.edu/login?url=https://www-proquest-com.ezproxy.libproxy.db.erau.edu/scholarly-journals/structural-transformation-supercooled-water/docview/910128750/se-2?accountid=27203

Pilot's handbook of aeronautical knowledge: FAA-H-8083-25B. (2016). Aviation Supplies & Academics. Retrieved 2016, from https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/pilot_handbook.pdf

Zielinski, S. (2011, November 30). At What Temperature Does Water Freeze? Retrieved December 11, 2020, from https://www.smithsonianmag.com/science-nature/at-what-temperature-does-water-freeze-1120813/

 

Foundation

    Core values are foundational to ethical choice. If my core values are “bad” yet I act within the constraints of those core value I am acting ethically, at least to myself. Every discussion of ethics carries the implication of “doing the most good.” Ethics mean nothing if not based upon an agreed definition of “good.” Can we “…rationally agree on a standard of measurement and also agree on how to apply that standard...?” (Hoppe, 2018)

    But this is an example of an inverted moral compass. As humans we set and follow our own individual standards or core values. What happens when we must choose between what is required of us and what our values are. Especially when it comes to “morally gray” areas.

      I frequently run into the problem of bad maintenance instructions. While the card must always be followed, there are ways to work around it. First, I must ensure that I have read the instruction correctly. Second, I should ask for help in interpretation or if someone has had prior experience. These two resources exhausted I will eventually have to decide whether to continue while using best maintenance practices, that is, doing a safe and effective job but not precisely following the card, or stop and risk possible negative consequences of not finishing a task.

     I do work in an environment where stopping and reassessing, or stopping altogether, in the name of safety do not carry negative consequences. But that does not stop the conflict inside of me where my desire to finish a project well opposes my desire to be safe. One of those must win out. And the winner is what my true core values are.

 

Hoppe, E. A. (Ed.). (2018). Ethical issues in aviation. ProQuest Ebook Central                

https://tinyurl.com/y27fwpat P. 5