What is the typical floor of Class E airspace at airports with an approved IAP?

The correct answer is that the typical floor of Class E airspace at airports with an approved Instrument Approach Procedure (IAP) is 700 feet AGL. Class E airspace exists to provide controlled airspace where Instrument Flight Rules (IFR) can be conducted safely, and it accommodates the altitude at which general aviation and commercial operations typically begin transitioning to controlled airspace for approaches and departures.

At certain airports, Class E airspace can start at 700 feet AGL when there is an established IAP, allowing aircraft to safely transition from terminal airspace to the higher altitude en route environment without encountering uncontrolled airspace. This floor level is particularly useful because it aligns with the vertical space that ensures separation from the ground-based obstructions and allows for a buffer against potential interactions with other controlled airspace that may start at higher levels.

While the other choices suggest different altitude levels, Class E airspace with an IAP specifically floor starts at 700 feet AGL. This configuration helps ensure safe operational practices for both IFR and VFR aircraft while maintaining a standard approach and departure path.