12 Winglets on the tips of an aircraft’s wings help reduce the amount of fuel used, saving billions of dollars for airline companies.

Most aircraft today have a “winglet” at the tip of their wing. These winglets help reduce natural vortices that form at the wingtips and thus lessen induced drag on the aircraft. This way, the tiny winglet allows aircraft to use up to 5% less fuel. For a typical Boeing 737 commuter plane, that adds up to 100,000 gallons of fuel a year! Consequently, winglets help save billions of dollars for the airline industry. (1, 2)

13 Airplane windows are always round, and not rectangular, to ensure the safety of the aircraft.

As we know, an airplane has to deal with high air pressure during a flight. With square windows, this would mean that their corners form weak spots on the aircraft’s body along which it could disintegrate. The solution to this then is to use circular windows. Since round shapes distribute pressure more evenly, circular windows provide more stability to the aircraft, making it safer.
(1, 2)

14 Dimming lights inside the cabin during takeoff and landing helps the eyes adjust to darkness quicker. This is crucial during an emergency.

Flight crews usually dim the lights in the cabin during takeoff and landing. But why do they do this? Typically, it takes the eyes about ten minutes to completely adapt to darkness. But in case of emergencies, this would be valuable time lost while passengers and crew members try to get used to dim lighting in situations such as the power going out.

So, by dimming lights in the cabin, it allows the eyes to adapt to the darkness quicker. Also, the emergency path lights and signs are more likely to be visible in dim light than in bright ones, making it easier to get off the plane. (1, 2)

15 The wings of an airplane have a red light and a green light respectively to help us determine the position of the aircraft.

The red and green lights on the wings of an aircraft are navigation lights, and they help determine the position of the craft to avoid collisions. Initially, they were used on ships and boats for this purpose. Then, this convention was implemented on aircraft as well, where the red light is seen on the port (left) side and the green light is seen on the starboard (right) side. In civil aviation, pilots are expected to keep the navigation lights on from sunset to sunrise, even after the engine is shut down at the gate. (1, 2)

16 Commercial airplanes are often struck by lightning. However, they are still considered safe during lightning strikes.

This is because standard commercial planes are designed to withstand lightning strikes and typically have carefully grounded electrical systems. Most of them even come out of lightning strikes either unharmed or with just minor damages. But to be safe, airplanes hit by lightning still undergo an inspection once they land to make sure everything is working properly. (1, 2)

17 Commercial passenger airplanes often have a lower wing placement, while military aircraft have a higher wing placement. These placements are chosen according to the airplane’s practical needs.

So, in commercial aircraft, low wings work well with the layout of the cabin and permit a passenger deck above and a separated cargo area below. It also makes sure that the engine is more accessible and refueling is easier during quick turnovers. Alternatively, in military planes, high wings provide the required cargo flexibility and operational advantages in rough terrain. (source)

18 Using cell phones on airplanes may interfere with cell service on the ground and cause disruptions.

In the US, the Federal Communications Commission (FCC) restricts cell phone usage on airplanes for this very reason. Active cell phones are likely to pick up signals from multiple towers, causing a disruption of service on the ground. Another common reason cited for this practice is that cell phones and other electronic devices may interfere with the sensitive systems of the aircraft. (1, 2)

19 Airplane windows often do not align with the seats because the seats are not placed with any real regard to the windows.

It can be quite frustrating if you get yourself a window seat on an airplane and find out that there is no window near you. But why aren’t seating rows always aligned with the windows? The reason for this is that airlines control how seats are placed in their planes and their objective is usually to fit in as many passengers as possible. So, the seats do not always align with the windows. (1, 2)

20 Turbulence is a patch of chaotic air that your plane may encounter while in midair. Pilots can often predict this by using weather reports and cockpit radar.

Turbulence can be understood as chaotic streams of air that make your plane ride bumpy. There are four kinds of turbulence. Clear air turbulence, as its name suggests, is the turbulence you experience even when the air outside looks pretty clear. Thermal turbulence, on the other hand, is caused by warm air rising that can then form clouds. Next, mechanical turbulence is caused by the flow of air around objects on the ground, such as trees or mountains.

Finally, wake turbulence is what a plane experiences when it comes in for a landing behind another aircraft. Pilots can often predict these by using weather reports, cockpit radars, and reports from other aircraft. They can also try and avoid turbulence by carefully planning their flight paths. (1, 2, 3)

21 Flight attendants ask you to set your seats in the upright position during landing and takeoff so that evacuation can be easier if there is an emergency.

In the US, however, this is also federal law. The FAA requires that all airplane seats be in the upright position during takeoff and landing. So, with the seats in the upright position, there is more room for the passengers behind you to get into the aisle to evacuate. Also, the brace position during a crash is easier to maintain when the seats are placed upright. (1, 2)

22 Although airlines have banned smoking, ashtrays can still be found on newer planes. This is because it is legally required for aircraft to have them.

Air passengers are often informed that smoking on board the aircraft is not allowed. However, some people may still smoke in spite of all the reminders and warnings. This is why it is legally required for aircraft to have ashtrays to provide a safe place to dispose of the cigarette despite the smoking ban. (1, 2)