Part 107 in Alaska: Twilight by the Air Almanac

Alaska has a federal Part 107 rule that applies nowhere else. Everywhere else in the United States, Part 107 defines civil twilight as the 30 minutes before official sunrise and after official sunset. In Alaska, §107.29(c) uses civil twilight as defined in the Air Almanac instead, which follows the sun's actual position. At Alaska's latitudes that window can be much longer than 30 minutes, and in midsummer it can last through the night.

Why does Alaska get its own definition?

Because a fixed 30 minutes would not match reality there. The Air Almanac defines civil twilight by the sun's position below the horizon. Near the equator the sun drops fast and twilight is short. At high latitudes the sun sets at a shallow angle, so twilight stretches out, and around the summer solstice the sun may never get far enough below the horizon for civil twilight to end before sunrise.

What does twilight change for your flight?

The same two requirements apply as everywhere:

• During civil twilight, the drone needs lighted anti-collision lighting visible for at least 3 statute miles, with a flash rate sufficient to avoid a collision.
• At night, after civil twilight ends, you also need the post-April 6, 2021 knowledge test or training described in the night operations post.

In an Alaska summer, a long twilight means many "evening" flights are twilight flights that need the light but not night training. In winter, short days push more flights into true night.

Does Alaska add its own drone law?

Not one that changes the Part 107 operating rules covered here. The Alaska-specific difference that matters for a Part 107 pilot is this federal twilight definition. Local rules, such as restrictions in some parks, can still apply.

What federal airspace matters in Alaska?

Anchorage sits under Class C airspace, and the state has many small airports, seaplane bases and military operating areas. Check the sectional chart and get authorization under §107.41 where needed. Floatplanes and low-flying bush aircraft are common, which makes the right-of-way rules very real.

What this means for the exam

This one can appear on the test. A question that asks how civil twilight is defined expects 30 minutes, except in Alaska, where it is the Air Almanac.

Other states are compared in the state drone laws guide.