Young 1, VIII-C

David Young

Technical Subject Areas

  1. Subject – Enroute and Lost Communications Procedures.
  2. Introduction – Although most people think of instrument flying as shooting approaches down to minimums, most of instrument flying is done during the enroute phase of flight. Flying IFR is much different than VFR, and it is essential to understand what those differences are, how to fly IFR enroute, and what to do in case of a lost communications situation (often termed lost comms).
  3. Outline –
  4. Discuss victor airways.
  5. Define the minimum altitude terms.
  6. Chart symbols.
  7. Required reports.
  8. Types of IFR altitude clearances.
  9. Review lost communications procedures.
  10. AVEF, MEA.
  11. Contents –
  12. In IFR flying, there exists “roads” in the sky (called victor airways)that are used to help us get from one point to another.
  13. Since we cannot rely on dead reckoning or pilotage, we must use more accurate methods which rely on instruments.
  14. Typically, victor airways are formed by radials coming off VORs which lead to other radials coming off other VORs.
  15. Many times there are defined points, or fixes, along these airways that are used to aid the pilot in navigation.
  16. Sometimes these fixes are defined by DME distances and other times by VOR cross-radials.
  17. These fixes might exist where an airway bends or where multiple airways intersect.
  18. Each fix is assigned a name i.e. LODGE or SIMMN (pronounced “Sy-mun”).
  19. When these fixes are not English words, it is best to just try and pronounce them the way they are written.
  20. There are many terms designated to differentiate types of altitude. These include MEA, MOCA, OROCA, MCA, MRA, MSA, MDA, and DA(H).
  21. On a side note, a minimum obstacle clearance altitude in non-mountainous terrain is 1,000 ft above the highest point and 2,000 ft above the highest point in mountainous terrain.
  22. Check the AIM for a depiction of “mountainous terrain.”
  23. MEA (Minimum Enroute Altitude) –The lowest published altitude between radio fixes which assures acceptable navigational signal coverage and meets obstacle clearance requirements between those fixes.
  24. It applies to the entire width of any federal airway.
  25. Usually designated as a number along an airway in enroute charts.
  26. MOCA (Minimum Obstruction Clearance Altitude) – The lowest published altitude between two radio fixes on VOR airways which assures acceptable navigational signal coverage within 22 nm of the fixes and meets the obstacle clearance requirements between those fixes.
  27. Usually designated as a * followed by a number for NACO charts.
  28. E.g. *3500.
  29. For Jeppesen charts, it is usually a brownish number followed by a “T”.
  30. E.g. 3500T.
  31. OROCA(Off-Route Obstacle Clearance Altitude) –The highest possible elevation, including terrain and other vertical obstructions, bounded by the ticked lines of latitude and longitude.
  32. OROCAs are usually depicted as follows: 125, which means the OROCA for that quadrangle is 12,500 ft.
  33. MCA (Minimum Crossing Altitude) –The lowest altitude at certain radio fixes at which an aircraft must cross when proceeding in the direction of a higher minimum enroute altitude.
  34. The MCA should be reached BEFORE reaching the fix it is defined for.
  35. Refer to Figure A for a depiction of a MCA on NACO charts.
  36. For Jeppesen charts, it is usually designated as something like “V64 12000S,” which means the MCA for V64 southbound is 12,000 ft MSL.
  37. Evaluation –
  38. References–

Figure A