Is there a way to code Minimum Enroute Altitude using ARINC 424 file format?
As the name suggests, MEA is coded for enroute segments lik ethe airways (ARINC permits this).  In so far as Instrument Approaches are concerned, the templates takes into account vertical clearances in Primary and secondary areas and then arrives at safe heights at each segment. Geometry of primary and secondary areas and the clearance therein depends on types of approach. For example, in ILS approach, half full scale deviation is considered safe. Also, it stems from this, obstacle clearance at different segments of the approach would be differen, so, specifying a minimum altitude may not be applicable. Secondly, in emergency, Minimum Sector altitude (MSA) centered 25 nm around airport/nav aid provides requisite obstacle clearance..