7 Secrets of Airplane Cabins Most Passengers Don’t Know

From crowded airports to packed planes and strict security rules, flying can be a stressful experience. With the complex nature of air travel, there are dozens of regulations and protocols that must be followed on any given flight, and most parts of the process are designed for a very specific purpose. It might help you breathe a little easier on your next flight knowing, for example, exactly why window blinds should be open for takeoff or what those pings over the airplane PA system really mean. Here are seven secrets of airplane cabins most passengers don’t know.

Cabin Lighting Has a Specific Purpose

You’ve probably noticed that the cabin lights on your flight are dimmed during takeoff and landing. Turns out, there are two very good reasons for this. The first reason is safety. If the lights stayed on at full brightness and were to suddenly switch from bright to dark in an emergency, it would take precious seconds for passengers’ eyes to adjust. With dim lighting during takeoff and landing, our eyes are already adjusted — making it easier to find an exit.

The second reason is the mood. Dim lights are more relaxing than bright lights and might calm a passenger who struggles with flight anxiety. Some airlines take this a step further by adding colored mood lighting — for example, on JetBlue Airways passengers will notice the airline’s signature calming blue color throughout the cabin during flight. 

Those Chimes Have Different Meanings

We’re all familiar with the pings that come over an airplane’s PA system during flight, but if you listen closely, you’ll notice subtle differences. These chimes are used to indicate important stages of the flight, such as takeoff, ascent, and descent — as well as communications between flight attendants and the cockpit.

Each airline has its own specific protocol, and these chimes can often vary. On many carriers, a double chime right before entering the runway usually means that the pilots have been given takeoff clearance, according to airline pilot Jack Herstam. 

After being airborne for a few minutes, you’ll notice another double chime indicating the plane has exceeded 10,000 feet in altitude — which is when it’s usually safe for flight attendants to start moving about the cabin and for passengers to use larger electronic devices. The same double ping occurs on descent when the airplane passes below 10,000 feet. And when the fasten seatbelt sign comes on and off, the indicator light will also be accompanied by a single chime. 

During the flight, you might also hear a single chime indicating a passenger has pressed his or her call button for assistance. A high-to-low chime means that flight attendants are trying to communicate with one another over the airplane’s phone system, according to a viral TikTok video from flight attendant Tommy Climato. A rare triple chime will indicate an emergency. 

The Temperature Is Cold on Purpose

Passengers sometimes complain about the cold temperature in airplane cabins. If you’re lucky, some airlines will provide passengers with a blanket, but it’s rare for the flight attendants to turn up the heat in the cabin. That’s because the temperature on an aircraft has been set in a very intentional way for your safety.

A study by ASTM International found that people were more likely to faint on an aircraft than on the ground due to a condition called hypoxia. The pressurized environment of an airplane cabin can prevent our body from getting enough oxygen, which causes fainting. The warmer the temperature onboard the aircraft, the more likely this is to happen. To prevent passengers from passing out, airlines intentionally lower the cabin temperature. While this might be slightly uncomfortable, it’s much safer for your body.

The Air Is Cleaner Than You Think

A common myth about air travel is that being confined in an airplane means you’re more likely to share germs and air particles with all the other passengers on board. In reality, modern airliner cabins have advanced HEPA — which stands for high-efficiency particulate air — filtration systems for maintaining clean air quality onboard the aircraft. 

According to the International Air Transportation Association (IATA), this is the same type of filter used to clean the air in hospital operating rooms. Cabin air is refreshed through this system 20 to 30 times per hour, which is more than double the average office building. Fresh air is brought in from the outside, which flows through the filter and helps to remove viruses and bacteria from the air — making the air you breathe on an airplane cleaner than you think.

Bathrooms Can Be Unlocked From the Outside

While there is a lock inside cabin bathrooms for passengers to use, flight attendants also have the ability to quickly unlock the door from the outside. It’s usually hidden under the “lavatory” sign on the door, which can be flipped up. This is for passenger safety: In the event of an emergency, flight attendants need to be able to access the bathroom without picking the lock or taking the door off its hinges. It also may be necessary if a passenger has a health scare or needs assistance while in the bathroom, or can also be used for children who are unable to unlock the door themselves.

Window Blinds Must Remain Open at Certain Times

During takeoff and landing, flight attendants on many airlines will ask that passengers lift their window blinds. Like other rules on an airplane, there’s an important reason for this. Open blinds allow the flight staff to see any issues on the ground or on the airplane itself. Passengers might also report unusual circumstances they observe from their windows. 

Lifting the blinds also allows our eyes to adjust to the conditions outside quickly in case of an emergency. However, while the practice is broadly recommended by international aviation safety organizations like the ICAO, there’s no blanket rule in place, so not all airlines will require it. 

There’s a Secret Hand Rail

Walking down the aisle of a moving airplane can be a wobbly experience — especially when there’s turbulence. Most passengers end up grabbing the seats as they walk, which can disturb the people in those seats, but there’s actually a better way.

If you watch the flight attendants, you’ll notice that they repeatedly reach up to the ceiling when they walk down the aisle. That’s because there’s a built-in handle rail along the bottom edge of the storage compartment, which can be used to steady yourself. Next time, follow the lead of the flight attendants and avoid aggravating fellow passengers — use this secret rail instead.