About 20 plane crashes this year , weren't there ?

[VectraMan]

All of this is fair comment, however there are risks in coasting to a halt in car, depending when/where it happens - as cars become more reliable people don't expect failures and so can react badly - you may be fine but the 44 tonne truck from the Czech Republic sitting a metre from your bumper may not even see you.

Of course. But I'd rather be in a car at 70mph without a working engine than in a plane at 30,000 feet (or 1,000 feet, it doesn't really make much difference) without a working engine. I would think statistically, you're many more thousand times likely to live through the former.

[doodab]

It seems to me a plane is inherently dangerous. If you're up in the air in a plane, you're not in a safe situation. You need the plane to keep working, the wings to stay attached, the engines to keep firing, the pilot to stay sober ,the ground crew to have put in enough fuel to reach an airport, etc. All these things have to happen to keep you alive.

The reason it's so statistically safe is because of the enormous amount of effort that goes into making sure all those things do happen. But they still fail, from time to time, and that usually means certain death.

A moving car is also inherently dangerous, but not nearly to the same degree. If your S2000 engine blows up (as has happened to me), you coast to a halt and you're fine. It's a PITA, and you get home late on an AA truck, but that's rather different than plummeting from 30,000 feet to certain death.

So it really comes down to whether you believe in statistics. Clearly most people don't, because otherwise nobody would be stupid enough to play the lottery.

Car's are primarily dangerous because of the risk of collision or driver error rather than the risk of mechanical failure, although obviously a tyre blow out can be pretty hairy and it's possible for e.g. gearbox / final drive failure to lock the wheels which can send you spinning out of control.

Arguably the same is true of aeroplanes, you are probably safest at 30,000 feet as most accidents seem to happen during take off and landing.

[Peoplesoft bloke]

Arguably the same is true of aeroplanes, you are probably safest at 30,000 feet as most accidents seem to happen during take off and landing.

Also the higher you are, the more time you have to sort things out provided something serious hasn't fallen off/blown up/caught fire already.

[minestrone]

My final year tutor of mechanical was tutored at university by one of the foremost aeronautical engineers in the country in the time, (his name escapes me now) he simply refused to fly as the factor of safety in airplane design is so low. OK that was in the 40s but even today planes still get away with having a far lower factor of safety than most other engineered systems we invest our safety in.

If we had never designed or built a plane but engineering advancement had continued at the same pace and someone came out with the design for the 747 today no country would pass it off as safe. It was basically wartime when safety concerns where thrown out the window where we made out biggest leaps in aeronautics.

Oh and I cannot get on a plane without being medicated due to a severe fear of heights, it's only because the girly can get a supply of cyclizine, lorazepam and valium for me I can get on a plane.

[stek]

Car's are primarily dangerous because of the risk of collision or driver error rather than the risk of mechanical failure, although obviously a tyre blow out can be pretty hairy and it's possible for e.g. gearbox / final drive failure to lock the wheels which can send you spinning out of control.

Arguably the same is true of aeroplanes, you are probably safest at 30,000 feet as most accidents seem to happen during take off and landing.

Think it's mostly take-off, anything going wrong then and it's almost certainly one for the Discovery Channel...

Whereas in flight and landing, so long as nothing big has fallen off the pilot can usually land it ok...

Wasn't there another crash today in Smolensk, Russia? Polish Pres. killed. Haven't read the whole thread tho!

[Peoplesoft bloke]

My final year tutor of mechanical was tutored at university by one of the foremost aeronautical engineers in the country in the time, (his name escapes me now) he simply refused to fly as the factor of safety in airplane design is so low. OK that was in the 40s

How old are you?

but even today planes still get away with having a far lower factor of safety than most other engineered systems we invest our safety in.

For example........?

If we had never designed or built a plane but engineering advancement had continued at the same pace and someone came out with the design for the 747 today no country would pass it off as safe. It was basically wartime when safety concerns where thrown out the window where we made out biggest leaps in aeronautics.

Thats a big and frankly crazy if. We have, we did, and designs are improving all the time. The 747-400 is like a totally different aircraft compared with the original 100-200 series as I am sure you must know as you have such a lot of knowledge of aviation engineering. Even the 400 is old tech now - old cars didn't have airbags and ABS but some people still drive 'em.

Oh and I cannot get on a plane without being medicated due to a severe fear of heights, it's only because the girly can get a supply of cyclizine, lorazepam and valium for me I can get on a plane.

Here I sympathise - I went through a phase of this, but am now much better at it again - hope you get it sorted like I did, cos I know it's no fun.

[minestrone]

I am 37 and passed my BEng hons in mid 90s so my tutor who was about to retire probably sat his degree in the 50s so his tutor would have been working through the 40s.

Onto factors of safety, you could probably tripple load a normal lift before you would see it fail, now I cannot prove that as they do not publish theoretical limits but in these types of system the ball park FOS is about 2.5 or 3. Now again I cannot provide evidence but in planes genreally have about a 1.5 FOS and I have been told that it can go down to 1.1 in some cases.

When you design a lift bumping up the FOS is not that big a deal, sure it adds on cost and weight but doubling of the lift cable is not a massive expense and the weight will only mean you have to put up the motor size. Now you cannot do that in a plane, the design of a plane component is 90% weight driven and you do have to cut corners.

I still stand by my statement that if we had just decided not to produce a plane and someone drew a plan up today nobody would have anything to do with it in these times of health and safety.

[minestrone]

I just googled and found a decent article on FOSs from a NASA engineer.

Most famously, the standard factor of safety for the cables in elevators is 11

so I was out on my guess of 3.

In the aircraft industry, a factor of safety standard is 1.5. Think about that when you get on a commercial airliner some time. The slim factor of safety represents the importance of weight in aviation. It also means that much more time, engineering analysis, and testing has gone into the determination of maximum load and the properties of the parts on the plane.



For some reason, lost in time, the standard FS for human space flight is 1.4, just slightly less than that for aviation. That extra 0.1 on the FS costs a huge amount of engineering work, but pays dividends in weight savings. This FS is codified in the NASA Human Ratings Requirements for Space Systems, NPR 8705.2. Well, actually, that requirements document only references the detailed engineering design requirements where the 1.4 FS lives.



Expendable launch vehicles are generally built to even lower factors of safety: 1.25 being commonplace and 1.1 also used at times. These lower factors of safety are a recognition of the additional risk that is allowed for cargo but not humans and the extreme importance of light weight

Actually quite a good read.

EDIT: forgot to put in the linky

http://blogs.nasa.gov/cm/blog/wayneh...459081779.html

[d000hg]

Flying is safe , it is safe trust me !

Mate , I pity the mentality in society that goes: "Flying is safe ! " . Tell that the families of the 29 crashed planes this year alone !

...

The real killers are the owners of Boeing and the other 1 , 2 monopolists. The ones that tell you flying is safe mate , just look how many people die from this or that. FLYING IS SAFE - the NUMBERS SHOW IT.

I'd rather be in a plane than a car, safety-speaking.

[minestrone]

If cars were allowed the freedom of space that planes were allowed then the car would be a safer means of transport.