Ultralight planes have quite simple yet effective parachute systems that can be deployed during an emergency. One big parachute is enough to make landing much safer – this helps passengers avoid serious injuries. But why big airliners don‘t have similar parachute systems? With our current technology, it seems, it should be possible to make a safe parachute-based emergency landing systems for such airplanes as Boeing 737 or Airbus A320, so why there aren‘t any?
If you think about it, there have been many aviation accidents that could have been avoided if there was a parachute system on the airliner. In fact, there have been animations online showing how a similar system would work, where the passenger section of the fuselage would simply break of the plane and land gracefully under the cupola of the parachute. However, reality is much more complicated. You would need at least a 125 meter wide parachute to reduce the falling speed of the Boeing 737 to 8 meters per second. This kind of speed would make for a harsh landing, but serious injuries would be avoided.
So we have a number – why there are no parachutes with 125 meter diameter? Well, simple answer is that it would be pretty much impossible to deploy such a large cupola and it would hardly maintain its shape. It is not a feasible option even. It would be much more realistic for an airliner to have a lot of smaller parachutes. Let’s look at an example.
Space Shuttle Solid Rocket Booster weighed around 91 tons coming down from its mission. Maximum weight of the Boeing 737 is smaller, but it is still a valuable example, because Shuttle SRB did not have to reduce its falling speed quite that much since it didn’t have passengers inside. This rocket had three parachutes, each with a diameter of 41 meters and it still hit the water in smashing 23 meters per second. That impact would be deadly in case of the airplanes. Boeing 737 would need 20 such parachutes to reduce its falling speed to 8 meters per second. One parachute weighs around 990 kg, but even that is not a full system.
Such large cupola would have to be deployed in stages – one small parachute pulls out the second stage and this one deploys the main landing parachutes. Experts calculate that such system for a Boeing 737 would weigh something like 23-30 tons – even reducing this weight to 20 tons it would be too heavy. Entire plane should be redesigned to fit such system. Planes would be heavier and less fuel efficient. Still, everything for safety, right?
Parachute systems need time to deploy so they would only work if the plane was still at high altitude when the problem occurred. And so, parachutes that are very heavy and bulky, would only help in some cases – they would not prevent all the accidents. If you consider all advantages and disadvantages the truth is clear – parachutes for big airliners are just not worth it. Especially having in mind that aviation is generally safe mean of transportation.