Welcome Guest. Sign in or Signup

1 Answers

Forward Slip with or without Flaps?

Asked by: 1207 views Aerodynamics

I've read articles and personal accounts of doing forward slips on purpose without using flaps. I was taught to always reduce the power and use full flaps prior to forward slipping (in a C172). On one of my flights, I was too high and fast on approach and decided to idle and forward slip, forgetting to put down the flaps, and I ended with the same high airspeed with the steep descent. So, are forward slips more appropriate with flaps down or up? What are the reasons for both? Is it aircraft dependent? Thank you.

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.

1 Answers

  1. Kris Kortokrax on Jul 31, 2016

    First, a forward slip is employed to control your descent path, not your airspeed. The Glider Flying Handbook contains a little better description of the maneuver, in that, it recommends raising the nose so that excess speed does not develop. The new ACS for Private pilot (which replaced the PTS on June 15th) has a requirement to maintain an airspeed that will result in minimum float on landing. With power at idle, you control your airspeed with pitch.

    Now to the flap issue. You need to look at the limitations section of the POH for the model you are flying. For instance, the 172S model contains a limitation against slips with one tank dry in excess of 30 seconds. The 172N has a requirement for a placard that states “Avoid slips with flaps extended.” Note that this is not a prohibition, but a recommendation. In the section on normal landings, both contain language stating that slips with greater than a 20 degree flap extension can cause a slight tendency for the elevator to oscillate. Again, not a prohibition, just a caution. In the same way that there is no prohibition concerning using flaps during a slip, there is also no directive that they shall be used. This is why we should seek out knowledgeable instructors, so that we don’t end up slaves to Old Wive’s Tales.

    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.