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January 2, 2009

The following stories from the January 2, 2009, edition of AOPA ePilot were provided to AOPA members who expressed an interest in the particular subject areas. Any AOPA member can receive information tailored to their areas of interest by updating their preferences online.

TRAINING TIPs

Standard temperature

As we move through the flying seasons, January’s cold challenges us to persevere, while offering some spectacular flight conditions. Engine preheats become the norm. Winterization kits are installed on many aircraft, perhaps modifying operating methods. During planning sessions, calculating aircraft performance using cold-weather operating values provides the information pilots need. See the Oct. 31, 2008, “ Training Tip: New seasons, new decisions.”

 

To use the performance charts in many pilot’s operating handbooks for general aviation aircraft, it is necessary to know the standard temperature and how much the ambient temperature deviates from it. For example, the cruise-performance chart for a 1980 Cessna 152 offers three sets of performance values at the aircraft’s cruise altitudes: one set of values for 20 degrees below standard, one for standard temperature, and one for 20 degrees above standard. Intermediate values require the use of interpolation, discussed in the March 12, 2004, “ Training Tip.”

 

Mention standard temperature and most student pilots can readily recite the figures of 15 degrees C or 59 degrees F, and a barometric pressure reading of 29.92 inches. But that’s not the whole picture. “The standard temperature is 15 degrees C but only at sea level. It decreases about 2 degrees C (or 3.5 degrees F) per 1,000 feet of altitude above sea level. The standard temperature at 7,000 feet msl, therefore, is only 1 degree C or 34 degrees F,” Barry Schiff explained in his July 2007 AOPA Pilot column “ Proficient Pilot: Density altitude discussions.”

 

Although the cold temperatures of winter do not pose the performance-robbing risk of a high-density-altitude condition, safe, accurate planning means using correct values in planning. For example, at a given engine speed, “a difference of 20 degrees C (34 degrees F) above or below standard will influence power by 3 to 5 percent with corresponding changes in fuel flow,” Marc Cook wrote in “ Airframe and Powerplant: Playing with power.”

 

Here is an easy method for estimating standard temperature at altitudes below 35,000 feet, from Section 2 of AOPA’s Handbook for Pilots .

  1. Double the altitude
  2. Divide by 1,000
  3. Subtract 15
  4. Change the sign

The result will be the temperature in Celsius.

TRAINING PRODUCTS

‘Transition to Gliders’

Have you been thinking about flying without an engine? Gliding and soaring is a fun and economical way to get into the sky, and it makes powered pilots more proficient. The sixth edition of Transition to Gliders, by Thomas L. Knauff, was written expressly for those who have a private pilot certificate in powered aircraft. Knauff has written several books on gliding and glider instruction and has set gliding records. The book sells for $29.95, and quantity discounts are available for flight schools and clubs. See the Web site for more information.


Note: Products listed have not been evaluated by ePilot editors unless otherwise noted. AOPA assumes no responsibility for products or services listed or for claims or actions by manufacturers or vendors.

FINAL EXAM

Question: I’m planning a career as a professional pilot, and I have heard that multiengine time is very important. Can I complete my private pilot training in a multiengine airplane?

 

Answer: It is perfectly acceptable for you to do your private pilot flight training in a multiengine airplane. Keep in mind, though, that your pilot certificate will be restricted to multiengine privileges only. FAR 61.109(b) outlines the requirements for obtaining your private pilot certificate in a multiengine airplane. You will find they are nearly identical to what would be needed in a single-engine airplane. Be sure to check out AOPA's subject report to read more about the differences between single-engine and multiengine flying.

 

Got a question for our technical services staff? E-mail to askft@aopa.org or call the Pilot Information Center, 800/872-2672. Don't forget the online archive of "Final Exam" questions and answers, searchable by keyword or topic.