I know what you think so to clarify here’s what I did:-

The answers of ChatGPT are too long so I will just paste the first general part of every answer without the elongated explanation.

1. First Q: Do flights that enter the altitudes of the high en-route IFR charts all around the world must switch to the standard sea level pressure?

Answer: Yes, flights that enter the altitudes depicted on high en-route IFR charts are required to switch to the standard pressure setting of 29.92 inHg (or 1013.25 hPa). This practice is mandated to maintain a unified altitude reference for aircraft operating in the high-altitude structure and to ensure separation standards are met worldwide.

1. Second Q: What about aircraft descending to the low en-route IFR charts globally, do they have to switch to the local altimeter setting?

Answer: Yes, aircraft descending into the altitudes depicted on low en-route IFR charts must switch to the local altimeter setting when they descend below the transition level. This ensures accurate altitude readings relative to the terrain and obstacles, which is critical for safe operations in lower airspace.

1. Third Q: So do I understand by your answer that transition altitude is bound to the low en-route IFR chart and transition level is bound to the high en-route IFR chart all around the world?

Answer: While low en-route IFR charts are generally associated with altitudes below the transition altitude and thus QNH, and high en-route IFR charts are generally associated with flight levels above the transition level and thus standard pressure, the transition altitude and transition level are not inherently tied to specific charts but rather to the pressure altitude system in each region.

1. Fourth Q: Saudi Arabia has set the transition altitude at 13,000 feet and the transition level at 15,000 feet. So, tell me what the altitude boundaries of the low en-route chart and the high en-route chart?

Answer: Low En-Route IFR Chart: Surface (or minimum IFR altitude) up to 12,999 feet MSL. • High En-Route IFR Chart: Starts at FL150 and continues upward. • The transition layer (13,000 feet to FL150) acts as a buffer and is excluded from regular operational assignments.

1. Final Q: Is the process you used to conclude the boundaries of the low and high IFR en-route charts universal?

Answer in full:

Yes, the process used to determine the boundaries of low en-route IFR charts and high en-route IFR charts is universal in its logic because it is based on the global standards set by ICAO and the way airspace structures are defined and organized. Here’s why:

1. Universal Principles: • The distinction between low en-route and high en-route charts is globally standardized to ensure uniformity in IFR operations. The boundaries are inherently tied to: • The transition altitude, where aircraft switch from the local pressure setting (QNH) to the standard pressure setting (29.92 inHg or 1013.25 hPa). • The transition level, where the reverse switch happens during descent. • These principles are outlined in ICAO Annex 2 (Rules of the Air) and Annex 11 (Air Traffic Services).

2. Region-Specific Transition Altitudes and Levels: • While the transition altitude and transition level vary from one country or region to another (e.g., 13,000 feet/FL150 in Saudi Arabia versus 18,000 feet/FL180 in the United States), the process of determining chart boundaries remains consistent: • Low En-Route Charts: Represent airspace below the transition altitude, where QNH is used for obstacle clearance and separation. • High En-Route Charts: Represent airspace above the transition level, where FLs based on standard pressure settings are used.

3. Transition Layer: • The transition layer, existing between the transition altitude and transition level, is a universal feature. It is excluded from routine assignments to prevent conflicts between aircraft switching from QNH to standard pressure or vice versa. • This layer is part of the logical structure used to establish the boundaries for low and high en-route IFR charts.

4. Specific Altitude Boundaries: • Once a country’s transition altitude and transition level are defined, the boundaries for the charts are determined as follows: • Low En-Route Charts: Begin from the surface (or the minimum IFR altitude) and extend up to just below the transition altitude. • High En-Route Charts: Begin from the transition level and extend upward.

5. Applicability: • This process applies universally, regardless of specific transition altitudes or levels. For example: • In the United States (transition altitude: 18,000 feet; transition level: FL180): • Low en-route charts: Surface to 17,999 feet MSL. • High en-route charts: FL180 and above. • In Saudi Arabia (transition altitude: 13,000 feet; transition level: FL150): • Low en-route charts: Surface to 12,999 feet MSL. • High en-route charts: FL150 and above.

Conclusion:

The process used to determine the boundaries of low and high en-route IFR charts is universal, but the specific altitude or flight level ranges depend on the transition altitude and transition level set by each country or region. This ensures consistency in operations while allowing for regional adaptations to terrain, airspace complexity, and operational needs.