Low Altitude Sectors are defined as which altitude range?

• A. Above FL600
• B. At and Below FL230
• C. Between FL200 and FL350
• D. At and Above FL450

Answer: (B)

Low altitude sectors are defined by a boundary that separates lower-altitude traffic from higher-altitude, or upper, traffic. The standard dividing line used here is flight level 230. So, sectors that handle flights from the surface up to and including FL230 are considered low altitude. Above this level, traffic typically moves into upper or high-altitude sectors with different routing, radar coverage, and separation considerations. The other options place the boundary at levels that don’t align with this common division, which is why they’re not correct for defining low altitude sectors.