I took this picture while flying from CYYC (Calgary) to EDDF (Frankfurt -FRA) on the Airbus 330 (big bus) six years ago.. This is the terminator- where night meets day. It's also called the "grey line" or the "twilight zone." Note the moon in the top right corner. This picture is found in my book.
Here's Wikipedia's definition: A red-eye flight is any flight departing late at night. The term red-eye derives from the fatigue symptom of having "red eyes" which can be caused by overnight travel. A red-eye flight typically moves from west to east during the overnight hours. It departs late at night, lasts only about three to five hours, an insufficient period to get fully rested in flight, and due to rapid forward time zone changes the aircraft lands around dawn. As a result, many travelers are unable to get sufficiently rested before a new day of activity. From a marketing standpoint, the flights allow business travelers an opportunity to migrate eastward without having an impact on a full business day.
Most eastward transatlantic crossings from North America to Europe are operated overnight, but are generally not viewed as red-eye flights since they depart early in the evening and last at least seven hours. A full night's rest is theoretically possible.
I'll be departing in a few hours for a flight to Calgary. We have a 90 minute pit stop and then it's back to Toronto on the "red eye" landing at 6:07 a.m. (Unfortunately, all the coffee shops close by then so I have to rely on the on-board 'gut rot'). Toronto Pearson has a curfew from 12:30 to 6:30 a.m so this flight, and a few others, are exempt. Air Canada flies daily red eyes from LAX, SFO, YYC, YVR and YEG (Edmonton).
The chatter on the radios this time of night is minimal and now and again you will here a pilot querying ATC whether they are still there. (Especially after the recent Minneapolis incident). As well, you know you are up late when you hear the nocturnal cargo crowd checking in on the airwaves.
I'll be home by 7:00 a.m and I doubt I'll be playing Air Canada pilot hockey at 10:00 a.m. I'll have to rest up for a flight to YEG in the evening. The good thing about "red eyes" is we are paid about 10 percent more for night flights. Night as far as pay goes, starts from 6:00 p.m local and ends 6:00 a.m departure airport time. At Air Canada most if us are paid by formula pay, and this is one part of the equation.