Airplane windows can and do break. Incidents with airplane windows breaking are really common and can be dealt with relatively easily as long as the aircraft is below 10,000 feet where pressurization does not pose any problems or danger to the passengers. Pilots are trained to deal with such emergencies.
So if they break so often, here are some of the most common questions…
When Do Airplane Windows Tend to Break the Most?
The most usual time for an airplane window to break is on take-off or after take-off if it comes in contact with a foreign object. This can either be a small rock, debris from a vehicle or another aircraft or, the most common reason is a bird strike.
Birds pose a big threat to aircraft and are most dangerous when the aircraft is in the takeoff run and during the climb up to 10,000 feet. Most bird strikes that resulted in an airplane window breaking or cracking were after takeoff up to 3,000 feet above the ground.
The combination of the aircraft’s high speed and the size and weight of the bird has resulted and will continue to result in the airplane’s windows breaking making it extremely uncomfortable and annoying for the pilots to land the plane back to safety.
This alone does not pose a big threat to pilots and can be dealt with as I said before in a relatively easy and very standardized manner. The difficulty is establishing communication with the other pilot as the sound is incredibly loud after a window breaks.
Can Cockpit Windows Inadvertently Open During Flight?
Besides breaking, the most common incidences involving windows is that if a pilot’s window is not closed and secured properly it can open during acceleration for take-off. This can result in the window’s hinges or the glass itself to shatter.
In most cases, and I am not proud to say in my case as well, the side window opened at around 100 knots on the takeoff roll and I was able to close it at 400 feet after putting the gear up.
No problems with the pressurization of the airplane occurred and the window and hinges were intact.
Apart from the sudden distraction, no matters of flight safety are affected due to the low altitude of the aircraft.
Once locked, cockpit windows are designed to stay locked and closed to prevent inadvertent opening leading to a sudden rapid decompression of the aircraft cabin.
As you can imagine, airplane windows are really robust and thick enough to withstand most bird strikes and Foreign Object Damage (FOD) which means that their production costs a lot of money.
Nevertheless, they do break. But when we say break, in most cases is not exactly what you imagine.
There’s no explosion or glass flying everywhere. Nine times out of ten, even in the most extreme cases the window just shatters and cracks but never breaks completely or flies off the aircraft.
Do Cabin Cabin Windows Break?
In general, the aerodynamic shape of the aircraft does not permit any object to strike the cabin windows while in flight. All bird strikes or debris impacts happen on the nose, wings, engines, and tailplane. The fuselage is pretty much impossible to hit while the aircraft is in flight.
Because of this, cabin windows do not have to withstand the impacts that the cockpit windows must take. If a cabin window were to crack it is usually from an object striking the window with the aircraft is parked.
Passengers are soon alerting the cabin crew to a broken window when they sit down, at which point the pilots are notified and another aircraft is usually exchanged to undertake the flight, while the window gets replaced.
What Can Cause Damage to Airplane Windows?
Apart from runway debris and birds severe hail stones are the third most common culprit of airplane window damage.
Aircraft often have to fly through severe thunderstorms during landing and departure, and usually without problems. One thing that occurs inside thunderstorms though is hail. Hail, in the mature stage of the thunderstorm and cumulonimbus clouds can reach up to 4″ (10 cm) in diameter and if an aircraft is hit by hail the damage to the cockpit windows can be severe.
Cockpit windows are designed not to break but will shatter and cause visibility problems for the pilots. The nose of the plane (where the weather radar is located) will be damaged way more than the window and it has to be replaced before the next flight. After flying through a severe hailstorm where the aircraft occurs damage it is often taken to a hanger for a full visual inspection to check for any other damage on the aircraft.
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Can a Passenger Open Their Window in the Cabin?
Absolutely not. Airplane cabin windows cannot be opened by anyone. Not even by certified engineers. Cabin windows are incorporated into the fuselage of the aircraft and have no mechanism to open. This is mainly due to operational reasons and also costs.
The only thing that a passenger can open in the cabin is the over-wing emergency exit only after clear instruction is received by the Captain in case of emergency. Passenger windows are sealed into the inside of the fuselage with rivets and sealant and are forced against the fuselage structure while the cabin is in flight due to pressurization.
It takes a team of specially trained personnel to remove and replace a cabin window as most last the lifetime of the aircraft.
How and When do Pilots Open the Windows?
Pilots only operate the cockpit windows on the ground and the main reasons why a pilot opens their window is for fresh air, hot weather or just to look outside and speak to the ground staff.
A common use for the window opening is communication with ground staff and the exchange of documents through the window in case the doors are already closed after boarding has been completed. This sounds like a small thing but actually reduces delays that could be caused if the doors had to be opened just for a document (Fuel receipt or dangerous goods declaration for example).
For the Boeing 737 800 series and the MAX there is a rotating lever that you pull inwards and then pull the window back.
To close the window there is a lever under the window that is only visible when the window is in the open position. First, you pull this lever, then pull the window upwards to the close position and rotate the rotating lever again until you hear a clicking sound. This ensures that the window is securely locked.
One extra use of the side window’s capability to open is for emergency use. If anything happens to the windows in the front (damage by hail or bird strike or anything else that degrades the visibility) the side windows can be opened so the pilot can literally stick their head out and see whether the aircraft is in the correct direction for landing. When on approach at 150knots this is not a comfortable experience but necessary if all the cockpit windows are broken.
Furthermore, the side cockpit windows can be opened for the pilots in case an evacuation is needed. In case the cockpit door cannot be opened due to fire or damage the pilots can use the emergency escape ropes to climb out of the windows to safety.
How Thick is an Airplane Window?
Airplane cockpit windows can be as much as 3 inches thick and side windows around 1″ thick. The forward-facing windows are designed to take high-speed object impacts and maintain their structural integrity. Each window is made up of layers similar to bulletproof glass.
Windows in the passenger cabin are less thick always as they don’t have to withstand heavy impacts and are not heated or have any technology in them. All aircraft cockpit windows are constructed in layers of impact-resistant glass with layers of plastic and UV ray protection in the inner layers.
Inside the aircraft cabin is a plastic window pane next to the passenger. A hole in the bottom side of this pane is placed so the pressure between the inside of the cabin and the layers of the window is equal. This prevents the plastic layer from breaking.
There is no ultraviolet radiation protection on passenger windows but there is a window blind available on all but the emergency exit windows to block out the sun or just for people to avoid looking outside.
If you found this helpful you may also like these other articles:
- This Is Why Plane Windows Are So Small!
- Can a Plane Takeoff in a Thunderstorm? An Airline Pilot Explains
- How Do Airplanes Handle Lightning Strikes?
- Why are Airplane Cabins Pressurized?