What is the jet route altitude stratum?

What is the jet route altitude stratum?

• A. Flight level 100 up to FL200
• B. FL150 up to FL350
• C. Flight level 180 up to and including FL450
• D. Flight level 200 up to FL400

Answer: (C)

Jet routes are the high‑altitude en route airways used for efficient long‑distance IFR travel. The altitude stratum for these routes runs from flight level 180 (18,000 ft) up to and including flight level 450 (45,000 ft). That’s why the correct range is FL180 to FL450. The other ranges correspond to lower or different en route structures, so they don’t match the standard jet route band. In practice, jet routes guide aircraft well above basic cruising levels, staying within that FL180–FL450 band.

Jet routes are the high‑altitude en route airways used for efficient long‑distance IFR travel. The altitude stratum for these routes runs from flight level 180 (18,000 ft) up to and including flight level 450 (45,000 ft). That’s why the correct range is FL180 to FL450. The other ranges correspond to lower or different en route structures, so they don’t match the standard jet route band. In practice, jet routes guide aircraft well above basic cruising levels, staying within that FL180–FL450 band.