(article) Flying Speed

[Wilfred]

ANN's Daily Aero-Tips (10.14.06): Flying Speed

 

Sat, 14 Oct '06

 

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.")

 

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. 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.

 

Look for our daily Aero-Tips segments, coming each day to you through the Aero-News Network.

 

Aero-Tips 10.14.06

 

We've been reviewing the FAA's list of the Top 10 causes of pilot-error accidents. Second on their list is failure to attain or maintain flying speed. Today we'll look at the first component of airspeed control: rotation or, more correctly, liftoff speed.

 

Liftoff speed

 

From the very first flying lesson we learn to allow the aircraft to accelerate to a certain speed, then lift off. In light airplanes we may not have to "pull" the airplane into the air with the control stick or yoke -- instead, we hold a little back pressure until the airplane lifts off on its own, for a smooth, pilot- and passenger-pleasing takeoff. Except in the case of a short-field takeoff, it's not until we fly heavier and multiengine airplanes that we accelerate to a specific airspeed and then pull back to lift off. We describe this action as "rotation", although purists will tell you that the term is really only applicable to turbine airplanes.

 

Using the "let it fly off" technique, we should have a good idea of the indicated airspeed at which this is supposed to happen. Further, we need to predict how much runway it should take to get to this speed-so if we're not accelerating as expected we can abort while there's still runway left.

 

Good attitude

 

Performance is a function of power and pitch attitude. Power is a function of engine type, density altitude and mixture leaning technique. If an indicated airspeed is our performance goal, then there will be one initial pitch attitude for the available power. Preflight planning (remember yesterday's Aero-tips?) should give you an indication of what to expect for takeoff power, and instruction and experience in the airplane an idea of the pitch attitude for desired performance. Hit your attitude and the airspeed should follow -- if it doesn't, adjust pitch and get ready to set it down if you don't get adequate climb.

 

Unable to attain flying speed

 

From the NTSB:

 

The airplane impacted terrain following the flight instructor and pilot's improper decision to continue the attempted high altitude takeoff when [flying] airspeed was not obtained, and failure to abort the takeoff…. Prior to takeoff, the run-up revealed no anomalies, the mixture setting was double checked, and the proper high altitude takeoff procedures were reviewed. The pilot said that he rotated at an airspeed of 70 knots after a ground roll of approximately 2500-3000 feet, which was consistent with their earlier performance calculations... The pilot reported holding the aircraft in ground effect to accelerate to the target speed of 96 knots. However, the airplane settled back to the runway, and lifted off again, at an airspeed of 80 knots. The airplane reached the end of the 11,021 foot runway at an altitude of approximately 150-200 feet, and an airspeed of 70-80 knots. As the airspeed began to decay, the pilot lowered the nose to avoid a stall. The pilot initiated an off-field landing with the aircraft touching down in a wings level attitude. Examination of the airframe and engine following the accident revealed no anomalies...

 

Aero-tip of the day: To avoid this common cause of aviation mishaps, failure to attain or maintain flying speed, know the airplane's liftoff (or rotation) speed, the approximate runway distance it should take to reach it, and the proper pitch attitude for initial climb.