As you can see, bourgeois twilight ends 32 minutes after sunset. 14 CFR 1.1 defines night as the period between the end of evening civil twilight and the beginning of morning sunrise. This definition is again mentioned in 14 CFR 61.109. Therefore, the day is defined as the period between the beginning of civil sunrise in the morning and the end of dusk in the evening. NOTE: These requirements do NOT mention the term civil twilight and refer only to sunset and sunrise. It is important to know the definitions here. When exactly does civil twilight end (and begin)? You need to dig a little deeper here. The FAA refers to the Navy Air Almanac. You can find civil twilight hours on the Navy`s website here. You can also use other websites, such as the FAA`s Sunrise/Sunset/Twilight calculator. You must enter the latitude and longitude of the place for which you are calculating civil twilight. My recommendation would be to find the latitude and longitude of your home airport and any other airport where you travel frequently and store this data in a text file on your computer. In this way, it is accessible to you if you want to calculate when the bourgeois twilight ends and begins.
For example, if I wanted to calculate the twilight time for KHUF airport, a quick Google search for “KHUF” or the 4-letter ID of the airport in question would display a link to that airport`s profile on Airnav.com. From there, you can retrieve the lat/long data in decimal format and plug it into the calculator. Take a look at the screenshot below of Airnav.com. According to the Navy`s website, civil twilight ends today at Rocky Mountain Metro Airport (KBJC) at 7:36 p.m. and begins again tomorrow morning at 6:40 a.m. So if you are travelling to KBJC, you can check in the night flight time at any time between 19:36 tonight and 06:40 tomorrow morning. How is civil twilight calculated? Here is the Navy`s definition: “Civil twilight is defined to begin in the morning and end in the evening, when the center of the sun is geometrically 6 degrees below the horizon.” A good rule of thumb for calculating civil twilight is that it usually ends between 20 and 35 minutes after sunset. Tonight at the KBJC, sunset is at 19:09 and civil twilight ends at 19:36. That`s a difference of 27 minutes. As long as you use your position and anti-collision lights between sunset and sunrise, record your night flight time after the end of civil twilight and record your night takeoffs and landings at least an hour after sunset, you`re good to go. The stages of twilight are based on the angle of the sun, and bourgeois twilight “is defined as beginning in the morning and ending in the evening, when the center of the sun is geometrically 6 degrees below the horizon.
This is the limit at which twilight lighting is sufficient in good weather conditions for terrestrial objects to be clearly distinguished. Luckily for us, the FAA decided it would probably be too much work for a reasonable person who flies frequently to figure out how to record night hours in their logbook. So they created a handy little calculator to determine when the bourgeois twilight ends and begins. According to the IAM and pilot/controller glossary, “civil twilight” is defined as follows: “Bourgeois twilight ends in the evening, when the center of the solar disk is 6 degrees below the horizon, and begins in the morning, when the center of the solar disk is 6 degrees below the horizon.” No. The FAA`s definition of NIGHT has nothing to do with sunset and sunrise. Sunset and sunrise have distinct definitions. Do not use them to calculate the start/stop times of the night hour recording. Then comes the civil twilight, and more precisely, when it ends. The FAA`s definition of night is included in section 1.1 of the FAR. Here`s what they have to say: “Night means the time between the end of evening civil twilight and the beginning of morning civil twilight, as published in Air Almanac, converted to local time.” If you fall into this period, you can record the night flight time, and your aircraft must be equipped with night VFR. If you need electricity at night to carry passengers, follow the definition of night as described in far 61.57 (b), the “period that begins one hour after sunset and ends one hour before sunrise.” Remember that to get night power, you need to perform three take-offs and landings at a standstill in an aircraft of the same category, class and type.
More information on night operation can be found in the AOPA Air Safety Foundation`s Safety Foundation`s Safety Safety Foundation`s Safety Hot Spot: Flying Night VFR. Given these definitions, what are the applicable FAR? If you are recording night flight time for private or commercial certifications, follow the definition in FAR 1.1. www.aopa.org/news-and-media/all-news/2005/october/11/night-flying-sort-through-the-different-definitions-of-night Well, there you have it, you have all the information you need, right there. Oh, not quite? Okay, let`s keep asking a few questions. According to the definition, we should be able to go to Air Almanac and know when the night officially begins. For the purposes of the settlement, how does FARS define the time of day? Is it sunrise to sunset, civil twilight, astronomical twilight? These nighttime uses are listed in order of increasing restrictiveness.
