If you’re a pilot you need to know the FAA’s definition of “night,” but it can be a bit confusing. It’s important because we have to log night flying time. In fact, we often have to log it to meet requirements and get credit for various certificates and ratings.
The FAA’s definition, according to the Aeronautical Information Manual (AIM), and the Pilot/Controller glossary goes as follows: “The time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the Air Almanac, converted to local time.”
Clear as day, right? Ha! Sure! Let’s take a look at what we’re dealing with a little closer here.
What Is “Civil Twilight?”
According to the AIM and Pilot/Controller Glossary, “civil twilight” is defined as follows: “Civil twilight ends in the evening when the center of the sun’s disk is 6 degrees below the horizon and begins in the morning when the center of the sun’s disk is 6 degrees below the horizon.”
Well, there you have it, you have all the info you need right there. Oh, not quite? Okay, let’s keep asking some questions. According to the definition we should be able to go to the Air Almanac and find out when night time will officially begin.
What Is The Air Almanac?
The Air Almanac is a publication put out by the The U.S. Naval Observatory every year. It is an enormous book of around 900 pages that has nothing but massive amounts of data, in table format, of calculations of where the sun, moon, and various other celestial bodies will be for EVERY DAY OF THE YEAR, in 10 minute intervals.
So if you want to know how to calculate the angle of the sun on the horizon for any day of the year, simply whip out your 900 page book, find the date and time, determine what angle the sun will be at relative to the horizon at what specific time, then convert it to your local time, and easy peezy, there you have it! Now you know when you can log night flying time 👍
What’s that? You don’t have an Air Almanac? You don’t feel like digging through a 900 page book, calculating the angle of the sun, and determining when it will be 6° below the horizon, and converting that to local time each time you go night flying? What are you, LAZY? Just kidding!
Lucky for us, the FAA decided this would probably be too much work for a sane individual who flies frequently, to know how to log night hours in their logbook. So they created a handy little calculator to determine when civil twilight ends and begins.
The FAA’s Sunrise / Sunset / Twilight Calculator
The FAA Twilight Calculator helps us determine when we can start logging night flight time.
It does require you to input the latitude and longitude of the location you are calculating civil twilight for. My recommendation would be to find the latitude and longitude of your home airport and any other airports you frequently travel to, and put that data in a text file on your computer. That way it’s accessible to you when you want to calculate when civil twilight ends and begins.
For instance, if I wanted to calculate the twilight time for the airport KHUF, a quick Google search of “KHUF” or the 4 letter identifier of the airport in question will turn up a link to that airport’s profile on Airnav.com. From there you can get the Lat/Long data in decimal format and plug it into the calculator. See the screenshot below from Airnav.com.
That circled data is what you need. It’s Lat/Long data in decimal format. If I were to put this data into a text file, I’d simply copy and paste the data in, next to the 4 letter identifier as follows…
KHUF – 39.4506325,-87.3069896
That way, it’s ready to go. Now if I plug it into the calculator I get this.
As you can see, civil twilight ends 32 minutes after sunset.
When Can I Log Night Flying Time?
Let’s not pretend. This is the real reason we want to know the FAA’s definition of night…so we know when we can log it! You can log night flying time whenever you are in the aircraft and civil twilight has ended. For Instance if you start a flight at 6 PM local, civil twilight ends at 7 PM local and you shut the engine down at 9 PM local, you can log two hours of night flying time.
Can’t I Just Use Sunset & Sunrise Times?
No. The definition of NIGHT from the FAA has nothing to do with sunset and sunrise. Sunset and sunrise have separate definitions. Don’t use those to calculate the times to start/end logging night hours.
Here is the definition of sunrise and sunset according to the AIM: Sunrise and sunset refer to the times when the upper edge of the disk of the Sun is on the horizon, considered unobstructed relative to the location of interest. Atmospheric conditions are assumed to be average, and the location is in a level region on the Earth’s surface.
As you can tell that’s different from the end of civil twilight. Take a look at the calculation from above. Civil twilight ends 32 minutes after sunset.
To further illustrate, try this experiment. Look at your weather app on your phone or look it up on the Internet somewhere of what time sunset is for this day or the next. Then take a look at how dark it actually is at that time. I think you’ll notice (if you’re being honest) that you can’t say it’s really dark outside.
What Are Night VFR Weather/Cloud Clearance Minimums?
Night VFR minimums are generally the same as they are for Day VFR (3 statute miles of visibility, 1,000 ft ceilings), however there are some exceptions in Class G (uncontrolled) airspace. Those nuances are outside the scope of this article. For an in-depth look at those minimums check out my guide to understanding VFR weather and cloud clearance minimums.
How Do I Stay Night Current?
If you haven’t flown at night for a while and you decide you’d like to go up at night with passengers, you need to make sure you are night current.
NOTE: These requirements DO NOT mention the term civil twilight, and only pertains to sunset and sunrise. It’s important to know definitions here.
Here are the night currency requirements under 14 CFR Part 61.57, summarized in my own words.
- You cannot act as PIC, carrying passengers, between the period 1 hour after sunset to 1 hour before sunrise, unless, within the previous 90 days you have made at least three takeoffs and three landings to a full stop during the period of 1 hour after sunset to 1 hour before sunrise, and…
- Have acted as the sole manipulator of the flight controls
- The required takeoffs and landings were performed in the same category, class, and type (if type rating is required).
See the FARs yourself for further clarification.
Conclusion
It’s tough keeping up with the regulations, definitions, and currency requirements for night flight. It is however, important to know for logging and currency requirements. Hopefully I’ve helped you understand it all a teeny bit better!
I love evening and night flying! The air is so smooth. It’s perfect for sightseeing before sunset and stargazing after sunset. Just be sure to glance at the instrument panel every now and then! 😜 Stay safe!
