Why don't planes have parachutes?

Colonial · 30-10-2015 9:34pm #1

Hey guys,

Why dont planes have massive parachutes released from the top if they fail?.... If failure, disable engines, open parachutes...

mulbot · 30-10-2015 9:37pm

http://thumbs.media.smithsonianmag.com//filer/3e/71/3e71f2dc-6948-4794-8668-090323539ba0/brs-parachute-system-2.jpg__800x600_q85_crop.jpg... some private planes do!

readytosnap · 30-10-2015 9:40pm

Probably too heavy and expensive. ( commercial aircraft I thought you meant)

NMB · 30-10-2015 9:42pm

I'm asking myself the question "Yeah, Why don't planes have parachutes ?"

luketitz · 30-10-2015 9:44pm

Have often thought same myself.. far more useful than a life jacket I would've thought.. although both would be ideal!

Manic Moran · 30-10-2015 9:49pm

The amount of cases where a parachute could make a serious difference is so small as to not warrant it. Cirrus makes a big deal about the fact that they equip their aircraft with parachutes, but in almost every case, they were used in incidents which could have been avoided by proper planning (eg fuel), or could likely have still been landed correctly (engine failure in cruise). Yet, despite the parachute, and a number of publicised incidents where it was used, Cirrus fatalities seem fairly high.

http://news.legalexaminer.com/cirrus-fatalities-have-critics-questioning-safety.aspx?googleid=262482

One theory is that pilots are more willing to take risks that they ordinarily would not, because they have that safety belt of the parachute.
For example:

Finally, there is one more factor to consider - the question of mindset.

In Cirrus’ attempts to create a “safer” airplane with a parachute that can be deployed when there is trouble, could pilots inadvertently be lulled into a false sense of security? Since there is clear documentation that the parachute has saved lives, perhaps this safety “fall back” has caused some pilots to become complacent about their proficiency or their training, or caused them to feel so overly secure, that they actually assume more risk by taking off, or continuing flight, in weather conditions they might not otherwise have tackled had they been flying different aircraft.

or

http://airfactsjournal.com/2012/05/dicks-blog-whats-wrong-with-cirrus-pilots/

A question that has to be asked is whether or not the pilot would have even been flying IFR in bad weather over rough terrain at night in his single-engine airplane if it had not been equipped with a parachute. I have always thought that a pilot who would do anything in a twin that he wouldn’t do in a single is an accident looking for a place to happen. Same goes with the parachute.

Colonial · 30-10-2015 9:58pm

Manic Moran wrote: »

The amount of cases where a parachute could make a serious difference is so small as to not warrant it. Cirrus makes a big deal about the fact that they equip their aircraft with parachutes, but in almost every case, they were used in incidents which could have been avoided by proper planning (eg fuel), or could likely have still been landed correctly (engine failure in cruise). Yet, despite the parachute, and a number of publicised incidents where it was used, Cirrus fatalities seem fairly high.

http://news.legalexaminer.com/cirrus-fatalities-have-critics-questioning-safety.aspx?googleid=262482

One theory is that pilots are more willing to take risks that they ordinarily would not, because they have that safety belt of the parachute.
For example:

or

http://airfactsjournal.com/2012/05/dicks-blog-whats-wrong-with-cirrus-pilots/

Educate pilots, if you use parachute you will likely die anyway with a +20% or whatever chance of survival... Alternatively make parachites than ffing work!

Guy:Incognito · 30-10-2015 9:59pm

How big a parachute would you need to get a commercial plane down (relatively) safely?

mrDerek · 30-10-2015 10:04pm

the weight alone for a parachute big enough to save a commercial liner wouldnt be very feasible long term because of the added cost in fuel

NMB · 30-10-2015 10:08pm

Ah the reality..... weight = money ..... so even if it was possible and it worked 1% of the time the weight of the material would out weigh the gain.

NMB · 30-10-2015 10:10pm

Or the material is so damn heavy the plane couldn't get off the ground in the first place perhaps - what's the physics ?

Go Tobban · 30-10-2015 10:19pm

Imagine the amount of pressure exerted on the plane once the chute opened

Would surely pull the plane apart

dubscottie · 30-10-2015 10:22pm

There was a documentary years ago about this. OK for small planes but useless for airliners.

IIRC a 747 would need one the size of 20 odd rugby pitches (although they use small enough chutes to drop 7-8 ton battle tanks from the back of Hercules planes) and then there is all the problems of the parachute covering the aircraft once it hits the deck. It would make escape difficult for passengers.

The weight as others have said.

The plane could also snap if it landed on say a house and burn anyway.

Shannon757 · 30-10-2015 10:30pm

Colonial wrote: »

Hey guys,

Why dont planes have massive parachutes released from the top if they fail?.... If failure, disable engines, open parachutes...

What if it was in a roll and the parachute got wrapped around the plane? Thatwould be a afar worse situation indeed.

LeBash · 30-10-2015 10:43pm

The top could come off the plane and individual parachutes for each seat. The parachute could be made of a soluble material and the seat could act as a floatation device.

Engineers are great at getting over problems if money is available to do it.

Shannon757 · 30-10-2015 10:46pm

LeBash wrote: »

The top could come off the plane and individual parachutes for each seat. The parachute could be made of a soluble material and the seat could act as a floatation device.

Engineers are great at getting over problems if money is available to do it.

The fuselage of a plane shouldn't really be designed to come off and if it happened over 10,000 feet then the passengers won't be able to breath.

dubscottie · 30-10-2015 10:47pm

Shannon757 wrote: »

What if it was in a roll and the parachute got wrapped around the plane? Thatwould be a afar worse situation indeed.

Good point. If a plane suffers a catastrophic failure, like a rudder coming off, it wont "glide" so a chute would be useless.

Saying that I think this is the record for the longest glide by an airliner in history.

https://en.wikipedia.org/wiki/Air_Transat_Flight_236

A quick google tells me that a 747 would need a chute with a min diameter of 501 meters!!!!

Shannon757 · 30-10-2015 10:51pm

dubscottie wrote: »

Good point. If a plane suffers a catastrophic failure, like a rudder coming off, it wont "glide" so a chute would be useless.

Saying that I think this is the record for the longest glide by an airliner in history.

https://en.wikipedia.org/wiki/Air_Transat_Flight_236

A quick google tells me that a 747 would need a chute with a min diameter of 501 meters!!!!

Well that was a fuel leak with no damage to the airframe so a glide should be relatively straightforward especially with an experienced glider pilot at the controls.

Del2005 · 30-10-2015 11:07pm

Since the vast majority of aircraft crashes occur during take off or landing a parachute would be useless. If they did design a parachute for large aircraft, which would require a lot more strength in the airframe, I doubt many passengers would survive the forces involved in a several hundred tonne aircraft going from 700km/h to zero in seconds.

Engineers would be better off designing new ways to get out of bed as a lot more people die doing that than in aircraft crashes.

filbert the fox · 13-11-2015 11:13am

Colonial wrote: »

Hey guys,

Why dont planes have massive parachutes released from the top if they fail?.... If failure, disable engines, open parachutes...

I recall when Black Box concluded the first series that the "sleep safely in your beds" reassurance went something like this:

if you boarded any plane anywhere every day for the next 27,000 years you would only be involved in one incident from which you'd probably survive.

Statistically, not worth it....

Sparks · 13-11-2015 2:13pm

Nobody's yet mentioned that the parachute would have to survive opening at high speed.
That's very non-trivial. A normal skydiving parachute opens at terminal velocity which is about 200kph; the Cirrus SR22 (one of the light aircraft that have these parachute systems) cruises around 320kph; but cruise speed for something like a 737 is around 950kph. And the energy involved goes up by the square of the speed...

InTheTrees · 13-11-2015 2:19pm

Its called a "ballistic recovery system" or BRS

You pull the Oh**** handle and it shoots a package containing the parachute clear of the aircraft where it deploys and drops you to the ground alive. Pretty cool.

http://www.brsaerospace.com/

https://en.wikipedia.org/wiki/Ballistic_Recovery_Systems

InTheTrees · 13-11-2015 2:21pm

Shannon757 wrote: »

What if it was in a roll and the parachute got wrapped around the plane? Thatwould be a afar worse situation indeed.

Umm. Thats why the parachute is in a unit that is fired away from the aircraft before it deploys.

Sparks · 13-11-2015 2:29pm

InTheTrees wrote: »

Umm. Thats why the parachute is in a unit that is fired away from the aircraft before it deploys.

That isn't why. It's fired away from the aircraft so the parachute cloth doesn't wrap around the tailfin the way it would if you just popped the back of the canister open in the slipstream around the aircraft.

InTheTrees · 14-11-2015 12:14am

Sparks wrote: »

That isn't why. It's fired away from the aircraft so the parachute cloth doesn't wrap around the tailfin the way it would if you just popped the back of the canister open in the slipstream around the aircraft.

Huh?

She said what if the parachute got wrapped around the aircraft and I said that's why its fired away and you say that's not right its because it might get wrapped around the aircraft?

Sparks · 14-11-2015 10:06am

That's not quite she said, which was:

Shannon757 wrote: »

What if it was in a roll and the parachute got wrapped around the plane?

But the BRS rocket isn't used to get the canopy away from the aircraft because of any manoeuvres it's carrying out, it's because if you just popped the canopy at point where it's mounted on the aircraft, the slipstream would just push the canopy all over the tailfin. It wouldn't matter if it was straight and level flight or not.

Shannon757 · 14-11-2015 12:33pm

InTheTrees wrote: »

Huh?

She said what if the parachute got wrapped around the aircraft and I said that's why its fired away and you say that's not right its because it might get wrapped around the aircraft?

He:mad:

Sparks · 14-11-2015 1:47pm

*lol*

Why don't planes have parachutes?

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