Aero-Tips!

A good pilot is always learning -- how many times have you heard this old standard throughout your flying career? There is no truer statement in all of flying (well, with the possible exception of "there are no old, bold pilots.") It's part of what makes aviation so exciting for all of us... just when you think you've seen it all, along comes a scenario you've never imagined.

Aero-News has called upon the expertise of Thomas P. Turner, master CFI and all-around-good-guy, to bring our readers -- and us -- daily tips to improve our skills as aviators, and as representatives of the flying community. Some of them, you may have heard before... but for each of us, there will also be something we might never have considered before, or something that didn't "stick" the way it should have the first time we memorized it for the practical test.

It is our unabashed goal that "Aero-Tips" will help our readers become better, safer pilots -- as well as introducing our ground-bound readers to the concepts and principles that keep those strange aluminum-and-composite contraptions in the air... and allow them to soar magnificently through it.

Look for our daily Aero-Tips segments, coming each day to you through the Aero-News Network. Suggestions for future Aero-Tips are always welcome, as are additions or discussion of each day's tips. Remember... when it comes to being good pilots, we're all in this together.

Aero-Tips 01.28.06

With the proliferation of turbocharged and turboprop airplanes and the onset of personal jets, more and more of us will fly high enough that we need extra oxygen, in the form of supplemental air or pressurization.  It’s critical to know not only when we need supplemental oxygen or pressurization, but also what may happen if our O2 system goes away.

Time of Useful Consciousness

Time of Useful Consciousness (TUC) is the amount of time a person has from failure of the oxygen system to the point he/she is so hypoxic that effective action is no longer possible. 

For a “normal, healthy” pilot TUC varies as follows:

1. Up to 20,000 feet, TUC averages five to 12 minutes... plenty of time to recognize a problem and descend to where natural air density is sufficient for extended operation.
2. At 25,000 feet, TUC drops to three to five minutes -- not much time to recognize a failure and repair it, or descend.
3. By 30,000 feet TUC is only one to two minutes, dangerous for a solo pilot and hazardous even when you have crewmembers to help you detect trouble.
4. Take your new Very Light Jet (VLJ) to 40,000 feet and the TUC is only nine to 15 seconds.

NOTE: The US Air Force prohibits flight above 25,000 feet in the unpressurized T-37 jet specifically because of the low TUC above that altitude.

ANOTHER NOTE: These numbers assume a supplemental O2 malfunction or a slow pressurization leak. Rapid decompression cuts them in half or more by sucking existing oxygen out of your lungs.

Effective Performance Time

These “book” times take the pilot from “fully functional” to “blubbering idiot” stage. When I took FAA physiological training in an altitude chamber at Oklahoma City I learned most people have an Effective Performance Time (EPT) of about half the above values, in which they’ll be functional enough to troubleshoot a balky O2 system or unstow, don and engage an oxygen mask (if not the quick-don type). If you’re a healthy nonsmoker, then, expect two to six minutes to act from the beginning of an O2 interruption at 20,000 feet.

Smokers, the FAA told us, can cut about half the time off both TUC and EPT. That makes it pretty dangerous for a smoker to fly above 14,000 feet using supplemental oxygen or facing a leak in a pressurized cabin higher up.

Aero-tip of the day: Just because an airplane or an O2 system certified to operate at 20,000 or higher does not make it safe to fly at those altitudes. You’ll learn a great deal about O2 use and your personal symptoms of hypoxia by taking an altitude chamber “flight.”

FMI: Aero-Tips