Terrain Avoidance Plan (TAP)<br>

July 1, 2004


This section provides night VFR pilots or pilots in areas of less-than-good visibility with a procedure to avoid Controlled Flight Into Terrain (CFIT). Plan the enroute portion of your flight to be at or above the altitudes shown below to avoid terrain or towers. Remember: Ceilings must be at least 500 feet above your cruising altitude when in Class E airspace.

Click on images for larger view. View the AOPA Air Safety Foundation's Safety Brief on Terrain Avoidance (PDF file — 178KB)
IFR en route low altitude chart
  1. Within the quadrangles of latitude and longitude shown on this IFR enroute low altitude chart the Off Route Obstruction Clearance Altitude (OROCA) is 3,500 feet. This altitude guarantees 1,000-foot obstacle clearance in non-mountainous terrain and can be used at night or when visibility is reduced to ensure obstacle clearance.

    The Minimum Enroute Altitude (MEA) highlighted on this chart is 6,000 feet. This altitude meets obstacle clearance requirements and provides acceptable ground based navigation signal coverage.

    The minimum obstruction clearance altitude (MOCA) highlighted is 3,000 feet. On NACO charts this altitude is shown with an *. MOCA is the lowest altitude between two fixes that meets obstacle clearance requirements. This altitude only assures an acceptable ground based navigation signal within 22 nautical miles of a VOR. Satellite based navigation systems, like GPS, will still receive navigation signals at these altitudes. OROCAs, MEAs, and MOCAs are found on IFR enroute low altitude charts.

VFR sectional chart
  1. The maximum elevation figure (MEF) in this area is 2,500 feet. This altitude represents the highest elevation, including terrain and other vertical obstacles bounded by lines of latitude and longitude. MEFs are only found on VFR sectional charts. MEFs may provide as little as 101 feet of obstacle clearance and are much less conservative then using the OROCA, MEA, or MOCA.
OROCA on IFR low altitude chart
  1. The OROCA highlighted here is 12,000 feet. This altitude offers 2,000 feet of obstacle clearance in mountainous terrain and can be used at night to ensure obstacle clearance. The only other altitude offered on this IFR enroute low altitude chart segment is an MEA.
VFR sectional segment
  1. The MEF in this area is 9,700 feet. MEFs are determined by rounding the highest elevation within the quadrangles to the next 100-foot level. These altitudes are then adjusted upward between 100 to 300 feet. Recognize this could give a pilot as little as 101 feet of obstacle clearance. Note the highest peak on this VFR sectional segment is 9,396 feet.

Try the AOPA Air Safety Foundation's Obstacle Clearance safety quiz to test your new skills.
View the AOPA Air Safety Foundation's Safety Brief on Terrain Avoidance (PDF file — 178KB).


Updated Wednesday, December 08, 2004 1:52:20 PM