Polly want a cracker?
How did the use of the term “squawk” originate, in reference to transponder codes?
Going incognito
The FAA requires many aircraft to display N-numbers that are a foot high. Which of the following are exceptions? (More than one may apply.)
- antique aircraft (a U.S. registered aircraft built more than 30 years ago, or an experimental category aircraft used either for exhibition purposes or amateur operation and having the same external configuration as one built at least that long ago) may have N-numbers only two inches high.
- experimental aircraft having a maximum cruising speed of 180 knots or less can use N-numbers that are three inches high (but they have to be on either both sides of the fuselage or both sides of the vertical tail surface).
- all airships, gliders, or balloons, but again, it must be on opposite sides (in the case of balloons, at points near the maximum circumference)
- an aircraft can get away with having no N-number displayed during an air show or the filming of a motion picture (or for practice and test flights, as well as en route to and from a base of operations)
- if an airplane was manufactured before November 1, 1981 and originally displayed two-inch marks, they may be left that way until it is repainted or the markings are otherwise repainted, restored, or changed
- none of the above
Different meanings
In an airship, what does the term “pressure height” mean?
- when the cells become 100% full
- when the airship flies through a low pressure area
- when the airship deflates due to very high pressure surrounding it
- when the strain on the envelope is within 10% of burst pressure
The Answers…
Polly want a cracker?
Answer: The origins stretch back into aviation’s earlier history, and as with many, this one goes back to the Second World War. After radar was developed, a method was needed to distinguish between friendly and unfriendly airplanes. The answer was transceivers that could respond to radar interrogations with a specific code. Allied aircraft could be identified by such unique codes while the enemy (for the time being) had no such codes. The Brits called the system “Parrot.” (The more common term was IFF, which stands for Identification Friend or Foe.) The radar station would instruct a pilot to “squawk his Parrot” (that is, to a specific code). While Polly has flown elsewhere, that term remains today, meaning to set a code in our transponders.
Going incognito
Answer: With the exception of the last choice (F), all of them. See Advisory Circular 45-2B, dated 7/16/03. Also, 14 CFR part 45 describes the rules for displaying registration markings and identification plates, and Advisory Circulars 43-3 and 43-17 cover the installation, removal, or change of aircraft identification data.
Different meanings
It’s choice A. As an airship rises higher where the air is less dense and where the external pressure decreases, the helium within the ship expands and the cells swell out. At a point called “pressure height,” when the cells become 100% full, any further ascent would result in increased pressure within the cells. If this were not relieved, it might eventually deform the surrounding structure and burst the cells. To guard against this, the cells are equipped with automatic valves set to open at a safe pressure and discharge their helium into the air. The Fujifilm web site has a pretty good “blimp glossary” if you’re interested.
