Welcome Guest. Sign in or Signup

1 Answers

Why are some MEA’s unidirectional?

Asked by: 3906 views , , , ,
Instrument Rating

Under IFR, you may use Victor airways to fly your intended route of flight.  These airways usually have a bidirectional MEA which makes sense to me.  But on occasion, you see a Victor airway that has a unidirectional MEA (one altitude for one direction and another altitude for the opposite direction).  What is the rationale behind this?  Why do they need to have different altitudes for the exact same route?

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. Best Answer


    John D Collins on Aug 30, 2015

    This is not an uncommon situation when flying into mountainous areas. When a route goes from a lower MEA to a higher MEA, the normal case is that at the boundary fix where the two segments meet, the aircraft is still at the lower MEA and then initiates the climb to the higher MEA. Obstacles and terrain along the route in the direction of the higher MEA are considered and as long as an aircraft maintains a standard 200 feet per NM climb gradient, they are assured of adequate obstacle and terrain clearance in the climb to the higher MEA. When this is not possible, the route designer has a few choices. They can establish a required minimum crossing altitude at the MEA transition fix, or they can raise the MEA of the lower segment. If they choose the latter method, then the question arises, do they need to penalize the opposite direction traffic and not allow them to use a lower MEA. In some cases, they lower the MEA in the opposite direction, because there isn’t a climb criteria to ovoid obstacles in that direction.

    +4 Votes Thumb up 4 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.