After the Chicago Center sabotage this week where a contract technician decided to complicate the upper Midwest ATC system, it got me to thinking about single point failure (SPF) modes—not for ATC but for pilots.
But first, how could the Chicago SNAFU happen? In my long-ago prior life in the USAF there were places where no person could be alone. Our nuclear missile launch control center had a two-officer requirement so if one of us got a little weird there was somebody right there to solve the problem. No single point failures! (Wonder if we could apply some similar thinking to other government activities—editorial comment.) We’ll let others rant about that, so let’s move on to operational topics.
Perhaps the most notorious aviation SPF over the years was the dry vacuum pump. I had a pump take an unplanned vacation with only 25 hours on it in solid IMC. The obligatory partial panel approach followed. After that experience, all the IFR aircraft I flew had a backup vacuum system. Darn if it didn’t happen again some years later in VMC, but the backup was there and it was a non-event. Both aircraft were well-maintained, but the perversity of hardware is always there.
On many older aircraft there are still people operating in IMC with this critical SPF. Not so good! If you “have a friend” who’s in this situation please encourage them to either not fly in IMC or GET A SUITABLE BACKUP! You can convince them with this Real Pilot Story.
With retractable landing gear there’s always an alternative extension mode: Most of the time it works and when it doesn’t let the insurance company fix or buy the aircraft. Avoid heroics to get the gear down that have led to catastrophe.
The system that gives me the biggest pause these days, after the engine itself, is the electrical system. We’re putting more and more eggs into the electronic basket. There are a number of options—a second alternator or a really good battery—but you better catch the problem fast. If that doesn’t work, the “Cat-Duck-and-Tree Method” can be employed, but it requires a lot of space and a substantial animal food budget. If you don’t know about that particular option see the fine print below!
The RAT might be a simple short term solution—not the four legged variety but a Ram Air Turbine. It’s been used on many military aircraft and airliners over the years. The Airbus 380′s is bigger than yours at more than five feet in diameter. It deploys manually or automatically into the slipstream and generates a modest amount of electricity. Haven’t seen that option for light GA, but I’m sure that somebody has come up with a solution.
Unless you’re flying one of the classic gravity-fed Cessnas, there’s probably an electric fuel pump to prime and to supplement the engine driven pump. Engine driven pumps don’t quit often but the electric pump is a potentially critical backup if the engine driven pump fails. Do you know the protocol for using yours?
Perhaps the ultimate backup is the Cirrus parachute. Some pilots look down their nose at it. However, if used correctly, it has saved quite a number of lives in addition to be being a great marketing benefit to persuade non-pilots to go fly. It didn’t help one optimist who tried to fly up the Columbia River Gorge in Oregon at night in MVFR. He was depending upon the terrain database to keep him off the rocks, but…well, you know.
“The Cat-Duck-and-Tree Method”
First, put a large cat on the cockpit floor. Because a cat always remains upright, the pilot merely has to see which way the cat leans to determine if the wings are level. Second comes the duck, which is used for approaches and landings in soupy weather. Any sensible duck will refuse to fly under instrument conditions, thus it is only necessary to hurl your duck out of the airplane and follow her to the ground.
For the most efficient use of the “Cat-Duck-and-Tree Method” follow this checklist:
- Get a wide-awake cat. Most cats don’t want to stand up at all. It may be necessary to carry a large dog in the cockpit to make the cat pay attention.
- Make sure your cat is clean. Dirty cats spend all their time washing. Trying to follow a washing cat usually results in a snap roll followed by an inverted spin.
- Use an old cat. Young cats still have many of their nine lives left, but an old cat has just as much to lose as you do and will be more dependable.
- Avoid cowardly ducks. If the duck discovers you are using the cat to keep the wings level, it may refuse to leave without the cat. Ducks are no better in IMC than you are.
- Make sure your duck has good eyesight. Nearsighted ducks may fail to realize they are on the gauges and go flailing off into the nearest mountain. Very nearsighted ducks may not realize they have been thrown from the aircraft and will descend to the ground in a sitting position. This is very difficult to follow in an airplane.
- Use only land loving ducks. It is very discouraging to break out of the overcast and find yourself on final approach toward duck blinds, because duck hunters will shoot at anything that flies.
- Since the floating compass in your airplane may sometimes go off track, you should always have a small tree hanging from the cockpit ceiling. Since moss grows only on the north side of a tree you merely have to see which side the moss is on to determine in what direction the plane is flying.
(Richard Taylor, author of Instrument Flying)