🔍 Key Concepts

• Pub. No. 249, Volume 1 is specifically designed for air navigation star sights, not general nautical reduction like H.O. 229/249 Vols. 2–3. • How stars are selected and listed in Volume 1 (by latitude bands and declination, not every visible star). • The difference between a complete star catalog and a pre-selected, limited set of stars for quick use.

💭 Think About

• Ask yourself: Does Volume 1 aim to cover all possible stars or just a practical subset chosen for ease and speed for air navigators? • Consider whether the main trade‑off in an air‑navigation table is accuracy vs. speed, or completeness vs. simplicity. • Think about which of the options describes a built‑in design limitation of the tables themselves, not something about how carefully you observe.

✅ Before You Answer

• Check which option mentions a restriction on which stars you can actually use with these tables. • Verify whether air‑navigation tables are generally more accurate, less accurate, or similarly accurate compared with ship‑navigation tables for practical use. • Eliminate any choices that describe requirements (like time spacing) that are not part of how Pub. 249 Volume 1 is actually used.