Avgas is colored by the use of a dye to indicate its octane and lead level. True or false: The higher the octane, the greater the number of letters in the name of the color used.
Answer: As we know, the nearly ubiquitous 100/115 avgas has a light blue color. Okay, blue: that’s four letters. The next-highest octane level for aviation fuel is 100/130, originally designated as the primary fuel for larger reciprocating single and multi-engine aircraft, and colored green. (This grade is usually also approved as a fall-back fuel for use in most Cessna, Piper, and other smaller general aviation aircraft.) That’s also one more letter. Going the other way, one step below 100/115 aviation fuel is the erstwhile 80/87 avgas, which was red in color and was used prior to the late 1970s. (Actually, it’s still available in some parts of the country.) So we have three colors; we also have three grades, and the color of each fits the pattern. Think that might be just a fortuitous coincidence? Would you still think that if you knew that there also used to be an even higher octane (and high lead) fuel, 130/145, intended for radial engines…and that it was…purple? So the answer to this question is: true. (It’s sure helpful to remember this “letter” rule the next time someone asks you which grade is what color.)
Side note: There are several methods of measuring “octane” rating, two of which are known as aviation and supercharge. (Others are research, and motor; the difference is mostly in the engine operating conditions and the measurement method for knocking.) For automotive gasoline, it’s the average of research and motor, which explains the “R+M/2” thing on gas pumps. For aviation gasoline, which are highly leaded, the grading comes in the form of two numbers: first from the aviation test (normally aspirated and with a lean mixture), and the second from the supercharge test (with a rich mixture). They’re not octane ratings as those used for cars, but “performance” numbers; determining the dependence of the highest permissible power in terms of indicated mean effective pressure on mixture strength and boost for a specific light knocking setting.
Low and Slow
You are flying an instrument approach at a stabilized airspeed of 100 knots. However, your aircraft’s power-off stall speed (in the landing configuration, at max gross weight) is 65 knots, which would put it into an approach category of 1.3 times that VS0 number of about 85 knots (actually, 84.5), which would put your aircraft in approach category A (which is up to 90 knots). You’re now flying in approach category B territory though (91 to 120 knots.) Is it required that you fly the approach using the Category B minimums?
- Yes, it’s the law.
- It wouldn’t matter actually, because very few approaches have separate minimums for Category A and Category B (either straight-in or circle-to-land), and the vast majority combine categories A and B.
- There is no such requirement.
- There is no regulation specifically mandating this, but it’s highly advisable that you do so.
Answer: It’s D. Here’s why. First, yes, the U.S. Terminal Procedures publication does state: “…If it is necessary to maneuver at speeds in excess of the upper limit of a speed range for a category, the minimums for the next higher category should be used.” (A descent is a maneuver too, incidentally.) True, you’ll find many approaches where the minimums are indeed lumped together for categories A and B, but by no means does that preclude the need to know the answer to this question. If you were coming out of the clag on the NDB approach at Coeur D’Alene, Idaho, that 100 foot difference in MDAs might be important! But back to the somewhat academic question: nowhere in Title 14 CFR does it give a definition of the imperative “should”. (It never says “must” or the even more definitive “shall”.) That said though, remember this: When you fly faster, you’ll need more room for obstruction clearance because of an increased turning radius, and lower altitudes for a lower category might not give you as wide a swath of maneuvering room. Also, fly faster, and you need more reaction time, which eats up more distance (so your visibility minimums should be greater, as well). Incidentally if you ever forget which category means what approach speeds, just look at a few approach plates. You’ll usually see maximum aircraft speeds for circling approaches shown in lieu of approach category letters. (This started with charts dated after July 27, 1989, and with good reason, as circling approaches are more hazardous and the less uncertainty as to what’s safest, the better.) You probably won’t see approach category E on any approach plates. That’s for aircraft with approach speeds over 165 knots!
The first CFI
The world’s first (civilian) flight instructor was
- Orville Wright
- Frederick W. (Casey) Baldwin
- Glenn Curtiss
- Walter Brookins
Answer: The Wright brothers may have astounded the nation early in the 20th century, but they also had to overcome more than just a little public prejudice. Even though mankind had dreamed of flight for ages, when most people came face to face with aviation in all its cacophonously clattering infant glory, some were just as likely to run the other way as they were to simply stand dumbfounded and gaping, open-mouthed. They knew that if they were going to win public acceptance, they would need more pilots to show just what airplanes could do. In addition to exhibitions, that also meant flight schools. (So Orville and Wilbur were, in a manner of speaking, the creators of the world’s first “Be A Pilot” program!) The very first pilot that the Wright brothers hired was one Walter Richard Brookins. (I know what you might be thinking: “Who?!”) He was a native of Dayton, Ohio, as well as an old friend. He attended the Wrights’ flying school near Montgomery Alabama, soloed in only two and a half hours, and became their very first instructor. His job was to train pilots for the new Wright Exhibition Team. In the year that he became the first “civilian pilot” he set records for altitude, becoming the first pilot to fly an airplane a mile high (actually, 6175 feet) and was the first pilot to fly at night. He was also the first pilot to demonstrate aerobatics. Yes, it’s D. By the way, his portrait is one of the thirty or so enshrined in the main hall of the Visitor Center at the Wright Brothers National Memorial, and you’ll find this story right beneath his image, much as I’ve related it.