Consecutive nighttime operations

This regulation limits how many consecutive duty periods can occur during nighttime hours when your body naturally wants to sleep (the "window of circadian low").

The basic rule: You cannot accept more than three consecutive flight duty periods that occur during nighttime hours.

However, there's an exception: If your airline provides at least 2 hours of rest in suitable accommodations during each nighttime duty period, you can accept up to five consecutive nighttime duty periods instead of three. This rest must meet the specific conditions in §117.15(a), (c), (d), and (e), and the 2-hour clock starts when you actually reach the rest facility.

Important note: If you receive split duty rest under §117.15, that rest counts as part of your flight duty period for this calculation—it doesn't break the consecutive count.

This rule recognizes that nighttime flying is more fatiguing and limits your exposure unless adequate rest opportunities are provided.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*