Welcome Guest. Sign in or Signup

4 Answers

How to calcualte the radius of turn required to clear obstacle

Asked by: 3996 views
Aerodynamics, Airspace, Commercial Pilot, Instrument Rating, Private Pilot, Student Pilot

You are a sightseeing pilot and you are flying in the middle of two mountains. The height of both mountains is 2000 ft ABOVE your current altitude. Your IAS is 150 kts with 20 kts tail wind, what is the minimum distance from the left or the right mountain that you must have in order to make a U-Turn (your position exactly in the middle) with 4 nm clearance of the mountain’s edge? I solved it but I want to check if I am correct. The website below is helpful. http://www.flightlearnings.com/2009/08/26/radius-of-turn/

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.

4 Answers



  1. MaggotCFII on Nov 11, 2013

    Try this link:

    http://www.csgnetwork.com/aircraftturninfocalc.html

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  2. Brian on Nov 12, 2013

    Depends on the bank angle. The formula to determine this is velocity squared divided by 11.26 tan (bank angle) where velocity is in knots and bank angle is in degrees. The resultant radius this formula gives you will be in feet.

    Source: AFNA p178 — http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/00-80T-80.pdf

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  3. Bob Watson on Nov 13, 2013

    If in doubt, slow down. Reducing your speed a little bit makes a big difference in turn radius.

    Also, IIRC, you want to turn into the wind and not away from it (i.e. start from the downwind side of the canyon) in that situation. Turning into the wind will shrink the radius of the turn whereas turning with the wind will increase it. If you’re already in a tight spot, you don’t want to see the mountains get any closer than they already are.

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes



  4. Clark Hall on Mar 01, 2014

    This can be a dicey situation. As was suggested start on the down wind side of the canyon and hug the canyon wall before starting the turn but watch for the down draft on the upwind side of the canyon. I suggest you go out in a big flat area with section lines so you have something to reference and do some turns to see how much room it takes. It is harder to look across a canyon and know the distance. Look at the ground as you do the practice turns over flat ground to get a feel for distance. This practice should be done at 500 feet or so if you are not used to flying that low. And work your way down.

    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.