Airport SID/STAR/Approach Primary Records in ARINC 424 contains two fields with altitudes: columns 85-89 and columns 90-94. How to interpret if both fields are empty ? What are the altitude constraints in this case?

Thanks in advance!


  • $\begingroup$ Could it be that there is no hard altitude at these fixes? If you provide the actual SID/Star this data comes from I'd be happy to check. $\endgroup$ Aug 31, 2023 at 18:45
  • $\begingroup$ Actually, I don't have any charts that cover Moscow... But, if you post the published procedure it might still help. $\endgroup$ Aug 31, 2023 at 19:00
  • 1
    $\begingroup$ @MichaelHall is correct. A blank altitude block indicates no altitude restriction. If you have a copy of the actual ARINC 424 manual, it explains what values may be entered in these blocks as well as the preceding column that indicates a + (minimum), - (maximum), or B (block) restriction. This has changed quite a bit since 424-18. There used to be a lot more available options. $\endgroup$
    – Timbo
    Aug 31, 2023 at 23:09
  • $\begingroup$ Thanks for your answers! I have ARINC manual. The manual have description of field 83 (Altitude description) and blank in this field means "“At” altitude specified in first “Altitude” field.". But what if the first "Altitude" field is empty? Let's assume that it means no altitude restrictions. Does this mean that the aircraft can fly at an altitude from the lower boundary of the sector to the upper one? $\endgroup$
    – Roman
    Sep 1, 2023 at 8:29


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