What is the Level-Off (L/O) Altitude based on?

The L/O Altitude is influenced by a combination of factors, including:

• Aircraft-specific climb performance
• How obstacle clearance data is presented in the AFM or equivalent documents
• Terrain and obstacle profiles along the departure path
• Meteorological conditions (especially wind and temperature)
• Gross-to-net performance degradation (e.g., 2-engine vs. 3-engine aircraft)
• The default level-off height configured for the aircraft tail per operator requirements

APG’s general approach is to model a climb to the default level-off height set for the aircraft. The aircraft then levels off and accelerates at the lowest altitude above that point where acceleration is possible without violating obstacle clearance. Any remaining obstacles are cleared during the fourth segment of the departure profile.

This explains why L/O altitudes can vary significantly between aircraft types and departure scenarios.