Archive for April, 2013

Confusing Spin Guidance

Wednesday, April 10th, 2013

Got a request from a reader in Canada who was confused by FAA wording on a placard. Imagine! Usually they’re pretty clear, including the near-worthless death and destruction placards that adorn many new aircraft as a result of our overly litigious society.

placardSee the photo: No English teacher would have written it that way. In my opinion, this could be far more clearly stated by saying, “All acrobatic maneuvers, including spins, are prohibited.”  I recommend a modest proposal to the FAA that they remove the word “approved” from the current verbiage.

chartNow to make things a bit more complicated, some aircraft are certificated in two categories depending on weight and balance envelopes, such as the one shown here. There is a normal category which prohibits aggressive activities; utility category allows increased Gs from 3.8 to 4.4. That’s quite a bit and in some aircraft, it will allow one to conduct spins if, and only if, those loading conditions are met. That usually means a forward CG. The C-172 fits this description: normal category—no spins, utility category—OK to spin. Some aircraft, like the A36 Bonanza, are also certificated in two categories, but spins are prohibited—period.

There are some CFIs who think that because normal category aircraft have been flight tested to recover from a one turn spin that one can tiptoe right up to the edge of the envelope by only doing one turn. This is not a great idea because those intrepid factory test pilots usually have: 1) a spin chute on the aircraft, 2) a parachute firmly attached to themselves, 3) some even have modified the doors on the test aircraft to make egress easier. Impromptu escape options usually don’t measure up to that. Awhile back I spoke to a young pilot who said she and her instructor had been doing one turn spins in a Cessna 210. I advised in the strongest terms possible of the above.

Describing chandelles, lazy 8s, and steep turns as acrobatic is pushing the definition. They are definitely maneuvering flight, but as long as one is not exceeding 60 degrees of bank or more than 30 degrees of pitch (by inference from FAR 91.303) they can be done in utility category aircraft.

Don’t forget if you’re practicing spins (in an appropriately approved aircraft) that parachutes may be required. If one is training for a CFI-airplane certificate, it is not required, but everyone else must wear a chute. This rule gets winked at a lot. Some CFIs introduce their primary students to spins without a chute on the premise that the student will someday become a CFI. That’s a stretch in my view although attorneys make a great living debating such things.

My opinion, not backed up by any statistics, is that the chute is there largely for psychological comfort. In most aircraft, unless the doors have removable hinges (quickly) or a canopy that jettisons (quickly), the odds of getting out are pretty slim if the machine is disintegrating around you and spinning earthward. We’ll have an upcoming segment on the topic on AOPA Live later this spring.

Would love to hear from someone who did escape with or without a chute, and the circumstances.

Murphism and Airplanes

Wednesday, April 3rd, 2013

pilotAny smart pilot or organization manager studies Murphy’s Law: life’s wonderful reality that if something can go wrong, it will! There are dozens if not hundreds of corollaries that remind us that complex airplanes are veritable breeding grounds for Murphy mischief.

In the March Issue of AOPA Pilot, I wrote about Air France 447, the Airbus 330 that went down over the south Atlantic after all three pitot tubes froze up. This caused the air data computer to leave the premises, and the automated systems, which the Airbus has raised to an art form, began cascading failures. The crew lost total situational awareness and the junior first officer, after some gyrations, pulled the big ‘bus into a stall and held it there for about three minutes for a final plunge from about 35,000 feet. Lots to learn from this one!

The saga of automation acting out continues. Here are two more incidents involving the Airbus where, once again, frozen pitot tubes discombobulated the autopilot, auto-throttle, and flight director. The crew managed to control the aircraft, but had to divert to an alternate airport because they couldn’t remain in reduced vertical separation maneuvering (RVSM) airspace and fly manually to the tolerance required. Guess keeping the tubes warm and dry is problematic.

The other incident involved a non-stabilized approach into Paris with another A340. This one had more help from the crew, with possible ATC assistance, in getting to the arrival gate not only high, but fast for a Cat III approach! The glideslope eluded them most of the way down. The aircraft at some point decided to go around, and a difference of opinion ensued between the crew and the ‘bus. It’s too long a story to relate here, but the crew and the automation never got on the same page, and let’s just say the outcome of the maneuver was seriously in doubt.

Before you think me anti-Airbus, recall that the Boeing Dreamliner, in pushing the performance envelope, has had a few miscues as well. Teething pains are one thing though, and ongoing incidents are something else—where one stops and the other begins is for your conjecture.

The principle concerning multifunctional devices states that the fewer functions any device is required to perform, the more perfectly it can perform those functions. Put more stuff on an aircraft, car, computer, home theater, or anything, and the reality is that it will break more frequently. DC-3s and Cessna 172s are prime examples of long-lasting simplicity.

Regarding automation for light aircraft, a certain amount is really good, and single-pilot flights in IMC without a simple and solid autopilot is much more work and distraction than it needs to be. However, remember Johnson’s First Law: When any mechanical contrivance fails, it will do so at the most inconvenient time.

My question is: How does it know?

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