At what altitude do Low IFR charts cover from the surface up to?

Low IFR charts are designed to support pilots operating in instrument flight rules conditions below a certain altitude. These charts typically cover operations from the surface up to 17,999 feet.

The reason 17,999 feet is the correct altitude is that it aligns with the transition to higher altitude airspace, which is governed by high altitude IFR procedures. Above 18,000 feet, air traffic control services switch to Enroute High Altitude charts, which provide specific routing and altitude information suitable for high altitude operations.

Understanding this boundary is crucial for pilots, as it informs them of where they can operate under Low IFR procedures versus where they need to transition to high altitude procedures, which can involve different navigational methods and air traffic service expectations.