Welcome Guest. Sign in or Signup

2 Answers

Using Left Rudder on a Descent. Is it Negative P-Factor?

Asked by: 3321 views , , , ,
Aerodynamics, Commercial Pilot, Flight Instructor, General Aviation, Private Pilot, Student Pilot

I know that my P-factor is greatest at high power and high angle of attack. To overcome that we use the right rudder, but my question is that does the P-factor changes in a descent? Because when I fly a 172, during a descent I experienced that left rudder is needed to keep the ball centered and my instructor says that it is due to change in the direction of P-factor but when I went over internet everybody says there’s no change in the direction of P-factor it’s effect just decreases while on descent. 

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

2 Answers



  1. KDS on Mar 20, 2020

    Here is a reference from FAA-H-8083-3B Airplane Flying Handbook. It is found under the subject of Glides in Chapter 3:

    Certain considerations must be given to gliding flight. These considerations are caused by the absence of the propeller slipstream, compensation for p-factor in the airplane’s design, and the effectiveness of airplane control surfaces at slow speeds. With the absent propeller effects and the subsequent compensation for these effects, which is designed into many airplanes, it is likely that, during glides, slight left rudder pressure is required to maintain coordinated flight.

    +2 Votes Thumb up 2 Votes Thumb down 0 Votes



  2. Craig Johnston on Mar 21, 2020

    The need for slight left rudder pressure is evident in at least these two places.
    The first is at top of descent when power is reduced from cruise. As the throttle is reduced, slight left rudder is typically needed to maintain coordinated flight. Otherwise, the airplane will be in a slight slip to the right.
    The second is when power is reduced in the traffic pattern when reducing power abeam the numbers. Slight left rudder is typically needed to maintain coordinated flight. Otherwise, the airplane will be in a slight slip to the right.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.