20 Interesting Facts About Air Travel

Commercial flights are some of the most important forms of travel in modern times. Chances are you took one recently for holiday traveling. But have you ever wondered why airlines do what they do? From why airplanes fly at a certain altitude to the reasoning behind the in-flight food choices, here are 20 interesting facts you might not have known about air travel.

1. The commercial narrow and wide-body airliner industries are dominated by just two companies: Boeing and Airbus.

Narrow-body airliners have just one aisle, while wide-body ones have two. Boeing and Airbus are direct competitors and have roughly equal market share. Combined, they take up more than 80% of all delivered planes. When comparing the value of the planes, their combined market share is roughly 95%.

2. Their most popular models are Boeing’s 737 family and Airbus’s A320 family.

As of 2018, there are 6373 planes from the 737 family and 7132 planes from the A320 family in service. Net orders for the planes are 11,447 and 14,096, respectively. If you’re just traveling around the country, chances are you’re on one of these planes.

3. The longest commercial flight is 19.5 hours…

Qantas tested this New York to Sydney, Australia flight in October last year. It’s a non-stop, 16,093 km (10,000 miles) flight on a Boeing 787-9. The previous record holder was the non-stop, 15,289 km (9500 miles) New York to Singapore flight by Singapore Airlines. That one took 18-19 hours.

4. …while the shortest one is only a minute and a half.

It’s hard to imagine a need for such a short flight, but it exists. It’s a flight by Loganair, a Scottish regional airline, between two islands north of Great Britain: Westray and Papa Westray. The route is only 2.7 km (1.7 miles), and with good flying conditions, the flight can take less than a minute. Apparently, it’s such a niche flight that just three pilots (on rotation) fly the route.

5. Airlines make most, if not all, of their profits from fees.

The current business model for the airline industry is to try to cover the expenses with the ticket and get profits from fees. And the fees bring in a lot of money. In fact, in 2017, US airlines took in roughly $4 billion in baggage fees and $3 billion in reservation-change and cancellation penalties. It works out to about $20 of profit from each passenger. That’s one of the main reasons why airlines have been trying to pack more passengers onto flights. More passengers means more fees, which means more profit.

6. The fight for overhead bin space is real and getting worse.

You can partially blame the aforementioned fees for this. To avoid checked baggage fees, many passengers are trying to pack as much as possible into carry-on luggage. Add the trend of stuffing more passengers onto planes and you can see why they run out of overhead bin space so often.

There’s another reason why gate agents will require people to check their bags roughly halfway through boarding, though. Gate agents are only allowed a certain amount of time to get everyone on the plane. People putting their luggage in the overhead bins is a bottleneck for the boarding process. So, after a certain amount of time, the remaining bags need to be checked to avoid delays.

7. Airliners typically fly at around 9.4-11.6 km (31,000-38,000 feet) for a reason.

Well, actually several reasons. The main one is fuel efficiency. The higher the altitude, the less dense air is, which means less drag. But it takes more fuel to reach higher altitudes, and airplane engines need air to work. Hence, that sweet spot. Airliners want to operate at cruising altitude as long as possible and typically reach it within 10 minutes of take off. The high altitude pretty much means all commercial airliners need to have pressurized cabins.

Other reasons include safety (able to descend faster in case of decompression or other emergencies), faster legal speed (faster speed limit for planes at 3 km (10000 feet) or higher), avoiding various types weather, and avoiding other air traffic.

8. Airliners usually travel at about 889-945 km/hr (552-587 mph)…

Again, this is mainly for fuel efficiency. Most modern airliners use high-bypass turbofan engines. These engines are most efficient at those speeds. A slower aircraft also means that the wing sweep (how swept back the wings are) can be less, which leads to a smaller, lighter, and less expensive plane. For the time being, it doesn’t seem like airliners are going to go any faster than current speeds.

9. …but airspeed is a bit tricky to define.

There are actually three different airspeeds that pilots see on an airliner. The first is ground speed, which uses GPS to measure. This how fast the plane is traveling relative to the ground. It’s only really important for estimating when the plane will arrive at its destination.

The second is indicated airspeed. This measurement is obtained from devices called pitot tubes. It’s important because certain flight characteristics, such as stall speed, occur at certain indicated airspeeds as listed in an aircraft’s manual.

The last one is true airspeed. It’s the speed of the plane relative to the mass of air around it. This is the speed that the previous typical cruising speed was given in. However, it’s not always the same as the ground speed. That’s because the mass of air the airplane is in can also be moving. For example, a strong tailwind, like from the jet stream, can push the airplane along making it much faster relative to the ground. One Boeing 787 flight reached an astounding 1289 km/hr (801 mph) by “surfing” a 372 km/hr (231 mph) jet stream. Likewise, headwinds can slow the airplane down relative to the ground.

10. Airplane wings use a variety of devices to change their in-flight properties.

If you have a window seat near the wing, you can see these in action, especially during take off and landing. The various parts of a flight (ex. take off, climbing, cruising, landing…) need different lift and drag characteristics. But since the plane can’t change its wing, it needs these devices to change the wing’s shape to fit those requirements.

The leading (front) edge of the wing has slats, while the trailing edge has flaps, flaperons (combination of flap and aileron), and spoilers. Here’s a diagram that shows some of those configurations:

Various wing configurations for different flight modes. The bright teal device is the slat, the two green ones are the flaps, and the red one is the spoiler. Source: Andrew Fry (https://en.wikipedia.org/wiki/File:Aircraft_flaps.svg)

11. The mechanism behind lift you probably learned in school is wrong.

The explanation you probably heard while growing up (at least I did) goes something like this. Airflow going over a wing and airflow going under the wing has to “reconnect” at the wing’s end. Since the top of the wing has a longer length than the bottom, air has to travel faster over the top to reconnect at the end. The faster flow means less pressure over the top of the wing, so the higher pressure below “pushes” the wing up, creating lift.

Yeah, that’s totally wrong. Not only does it violate Newton’s third law (there’s a lift force but no counter downward force on the airflow), there’s nothing that requires that the air at top has to reconnect with the air at the bottom. In fact, the air flowing over the top of a wing goes much faster than this model suggests. Also, the fact that airplanes can fly upside-down easily disproves this model.

Instead, it’s a mutual interaction between the pressure and speed of the air around the wing that creates lift. There’s a bunch of complicated physics involved, so I’ll just give you a summary.

The shape of a wing (or its tilt for symmetrical wings) slows air flowing under it and speeds air flowing above it. This creates a localized low-pressure area above the wing and a high-pressure area below the wing. Air accelerates from high pressure areas to low pressure areas. So, air above and around the low-pressure area flows toward the low-pressure area, while air around the high-pressure area gets pushed away from the high-pressure area and, at the ends of the wing, slightly upward (because of the lower pressure above the wing). This motion combined with the rest of the airflow moving past the wing results in a net downward “turning” of the air. By turning the air downward, an equal and opposite upward force (Newton’s third law) acting on the wing is created, which is lift.

The pressure difference affects the speed of the airflow around the wing, and the speed of the airflow maintains the pressure difference. The interaction is mutual and simultaneous.

12. Today’s jet engines are ridiculously powerful.

The high-bypass turbofan engines that newer models use have some absurd thrust outputs. For example, the current record holder, the GE9X, has a max thrust output of 597,396 N (134,300 pounds) of thrust. And the Boeing 777X that uses them has two of these! They most likely won’t ever need to be throttled to that level, but it just shows just how powerful these engines are.

The previous record holder, the GE90-115B, had a max output of 568,928 N (127,900 pounds) of thrust, and it could already send cars flying and even tear up a runway as the clip below shows.

The GE90-115B during a test. Source: GE Aviation (https://www.ge.com/reports/the-worlds-largest-jet-engine-is-already-more-powerful-than-americas-first-manned-space-rocket/)

13. Twin-engine airliners can fly with just one engine.

Yup, in most cases, a twin-engine airliner that lost one of its engines can still fly. It’s not without problems, though. It won’t be able to maintain cruising altitude, for one. In addition, a dead engine creates a lot of drag. This combined with the increased output of the remaining engine to compensate for the loss in power means that the plane will want to turn. Pilots have to correct this motion manually by using the rudder. Landing is also trickier due to this. Furthermore, the engines generate power for the plane, so some electronic systems may have to be shut down, which can affect the plane’s handling.

14. Your sense of smell and taste is different on an airplane.

If you think airplane food is bland, it’s probably not just you. The low pressure and humidity inside an airplane at cruising altitude mess up your sense of smell and taste. Since you need both to taste food, stuff tastes different than what you’re used to on the ground. Sweetness and saltiness are the flavors most affected, while sour, bitter, and spicy flavors are mostly fine.

Surprisingly, the loud background noise also affects your sense of taste. People who eat in the presence of loud background noise report that the food is less sweet and salty. They also think that the food is crunchier. Weird. Perhaps the most surprising find is that loud noise actually enhances the savory taste. It’s probably why foods that have a lot of this taste, such as tomato juice, are popular on airlines.

15. Airlines determine the in-flight food menu based on a number of factors.

The alteration to your sense of smell and taste while flying is just one of the factors chefs have to consider when designing a menu for airlines. They also have to consider regional tastes, ease of preparation and storage (food has to be cooked on the ground then stored on the plane for later reheating), and also cost. The meals often go through a lot of testing on the ground. Sometimes airlines even get flight attendants to sample food on actual flights and use their feedback to improve dishes.

16. It’s risky to drink the water on a plane.

One thing you really shouldn’t order on a plane is anything that uses the plane’s water (ex. hot coffee and tea). This is because the water tanks are rarely emptied or cleaned. As a result, it can harbor unhealthy levels of bacteria, such as E. coli. Obviously, there are regulations for these things, but it seems their enforcement is too lax to make them effective. Thus, your best bet is to only drink beverages that come in a sealed container.

17. Your flight may also be carrying mail.

Mail needs to get to places fast, and one efficient way is to have airliners carry some of it along with passengers’ luggage. The mail is grouped together and put into special containers that fit under the passenger cabin. The US Postal Service (USPS) alone leases space on roughly 15,000 flights a day to help carry mail. In fact, airlines make about 5-10% of their revenue from hauling mail.

18. Being a flight attendant is hard work.

Flight attendants are far from glorified waiters/waitresses. They have ever-changing schedules (to account for flight changes/delays) and have to go through rigorous training to prepare them for any kind of situation that can happen on a flight. That’s all in addition to other duties like preparing and serving food, helping passengers, and performing safety and security checks. Some flight attendant schools, such as Delta’s, have a lower acceptance rate than Harvard (1% compared to 4.6%).

19. Flying increases your exposure to cosmic rays.

Cosmic rays are a dangerous form of high-energy ionizing radiation from space. The Earth’s atmosphere pretty much filters them out at ground level. But since the air is much thinner at an airplane’s cruising altitude, your exposure to them is greater on a flight. But even so, the amount of ionizing radiation exposure you get from them (even for frequent fliers) is pretty small. They make up only about 11% of your total annual radiation dose.

20. Air travel is a major factor in spreading disease.

With airplanes, it’s now easier than ever for diseases to travel to places they couldn’t reach before. It’s all the more apparent with the current coronavirus outbreak. When you travel, be wary of your surroundings and be sure to wash your hands thoroughly (and maybe wear a face mask) if you come into contact with anyone who’s sick.