DH (Decision Height)

The altitude during an instrument approach (measured above runway threshold elevation) at which the pilot must decide whether to continue the approach or execute a missed approach. If the required visual reference (runway lights, markings, or environment) is not clearly visible at the DH, the approach must be abandoned.

Key characteristics:

• Measured with a radio altimeter (height above the runway threshold, not MSL).
  
  
• Applies to precision approaches such as ILS (CAT I, II, III).
  
  
• Standard values:
  
  
  • CAT I: 200 ft DH
    
    
  • CAT II: 100 ft DH
    
    
  • CAT IIIa/b: below 100 ft / as low as 50 ft
    
    
  • CAT IIIc: no DH (true zero-zero, fully reliant on autoland).
    
    
• Safety role: Prevents pilots from descending below safe altitudes without visual contact.

Application in DCS World

• Cadets can practice respecting decision heights by flying ILS approaches in poor weather and setting personal DH values (200 ft for CAT I, 100 ft for CAT II, etc.).
  
  
• DCS does not display DH on approach charts, enforce missed approaches at DH, or model real-world RVR requirements. It also does not simulate radio altimeter callouts as rigorously as in certified aircraft.
  
  

Cadets should train to announce “Decision Height” at the correct altitude, look for visual cues, and practice executing a go-around when the runway environment is not visible. This builds disciplined instrument flying habits.