This is too long to write as a comment, so here goes. Before I begin – Dad, I got the letter you posted in the mail from Australia. Thanks!! Nice to see Aussie stamps for once.

So let me address a few of your concerns.

THE SAFETY OF SKYDIVING
First, I completely understand what you say about safety and seemingly dangerous sports, and if I was a parent I would probably think the same if my child did something like this. The only way I can think of to persuade you otherwise is to explain thoroughly to you over the phone why I think it is safe, and I will do that for as long and as many times as necessary to convince you.

But for now, remember that I am an engineer and I am very aware of what is safe and what is not safe. If I thought that skydiving was not safe, I would not do it. You know I am a safe person just from the very conservative way in which I drive, for example. I am thoroughly convinced that the safety equipment and training for skydiving is extremely rigorous, as I will explain to you more over the phone. In short:

Equipment – In skydiving we check the equipment (and review emergency procedures) on the ground and on the plane 3-4 times before jumping, and we check each other’s gear, as well as our own. Contrast that to when you drive a car: you don’t visually inspect the brake pedals, indicator lights etc each time you drive.

Additionally, the more I learn about parachutes and skydiving equipment the more I am impressed with its safety and multiple redundancies. There are at least three independent ways to deploy the reserve parachute, for example: a handle, the reserve static line, and even an onboard computer – yes, the parachutes we jump with these days have a computer that can measure your velocity and altitude. Again, I’ll explain more on the phone.

Emergency procedures – If you encounter an emergency while driving, would you know what to do – a slippery or icy road, brakes that suddenly fail, etc.? I don’t remember ever learning that when I learnt to drive. What about skiing – no one needs to take formal lessons or get a license to ski, and yet think of the high speeds and potential for collisions on any ski slope. In contrast, for skydiving, probably 50% of all the ground training is just repeating and reviewing emergency procedures – videos, simulations, written and oral quizzes. It is very rigorous, even by my engineer’s standards. In fact, this level of rigor approaches that of NASA astronaut training, in which ~80% of simulator time is devoted solely to emergency procedures (again, in contrast to learning to drive: 5%, perhaps?)

In terms of F1 racing, you do see racecars in flames on the news because it is spectacularly grisly footage, just as you see footage of car crashes on the highway – but I’m sure that won’t stop you driving your car. Furthermore, if you investigate a little, you will see that race car safety technology is directly responsible for many of the safety innovations we enjoy in ordinary cars today.

WHY SKYDIVE?
As for why I skydive – same reason you go bushwalking and read books, or why I play the piano and watch movies, or why Wei plays PS3, or why Mum is secretary of 侨青社 (well, maybe not the last one, haha!). It’s fun, exciting and challenging. More specifically:

* It is somewhat part of my little boy’s astronaut dream – the same dream that motivated me to apply to MIT. I hope you don’t mind that I attended MIT? :-)
* I like to fly and be in the air. It’s cool… and skydiving is MUCH cheaper than flying planes. I can’t help it.. and since I am your son, I must have partially picked this up this interest from you!
* There are several unique challenges in skydiving that I want to meet and conquer. First is learning to concentrate very, very intensely for a very short period of time; I could spend an hour visualizing and thinking about a short, 60-second jump before actually doing it (yes, yes, I know I could do this in other activities too, but anyway.). Second is concentrating while learning to understand and control my natural apprehension and fear – it is fascinating to learn to act smoothly and steadily, even when falling through the air very fast, which is a very unnatural situation (as I’m sure you’ll agree!)

Skydiving is completely different to those idiots who climb up the side of buildings with no safety equipment. That is just dumb, as well as insanely dangerous. The thrilll in such an activity is in the danger itself. In contrast, the thrill in skydiving is NOT the danger – it is NOT the feeling that you are close to being killed. No way. The thrill is in feeling free fall, the sensation of flying, the spectacular view, the calm of flying a parachute gently to the ground after exhilarating free fall. I repeat: the thrill is NOT in the danger, not at all. If it was, I would not see mothers and grandparents skydiving.

Furthermore, skydiving is not as extreme as you think. THOUSANDS of people skydive every year – even just once in their lives during a tandem jump. The US Parachuting Association, which governs skydiving safety and policy, has about 31,000 members. At my drop zone I know plenty of ordinary mothers and grandfathers jumping regularly, and they are calm, safe, ordinary people – and they bring their kids too (but the kids don’t jump, of course). The drop zone I go to has a nice, family-friendly attitude, so much so that there is a kid’s playground outside and nursery inside (I’ve been in the nursery there to use the wireless internet. Even the wall sockets have childproof devices on them. It’s a safe place.)

As for something like canyon tightrope walking, you will find much, much fewer people doing it, and they fall into two categories: extremely highly trained professionals or hooligans/idiots. There is a much smaller line between fun and danger there, and I, for one, would never try it, because the risk/reward ratio is far too unattractive for me (and I’m not interested anyway.)

I don’t expect you, or even most people, to understand or agree with these motivations, and I appreciate your concern and perhaps disapproval.

WASTE OF MONEY?
As for the point about money – well, we just have to agree to disagree here. I understand if you think it’s a waste of money, but then again I think that you waste money on some things too. The only thing I can say is that you don’t have to worry about my financial situation – I earn plenty and save plenty. If you want me to quantify this, I can.

INCREASING CARBON FOOTPRINT
The final thing I would mention is your point about increasing carbon footprint. I’m very sorry, Dad, but you are not the right person to criticize me about this. Sure I increase my carbon footprint by skydiving, but if you want to criticize me for that, then you should also criticize me for flying to Australia and Malaysia (one round trip from Boston to Sydney releases as much CO2 as driving a car for a couple of years.) You should also consider that

* You and Mum drive very big cars, which I think is unnecessary. How often are you the only occupant, especially now that Wei and I are gone? At least one of you can survive perfectly well with a small hatchback-sized car. Furthermore, the all-wheel drive on your Subarus definitely increases your fuel consumption a few percent over equivalent 2WD cars. I know that 4WD supposedly increases safety in the wet, but it’s overkill; most people survive just fine with 2WD. Drive slower, if you have to.
* You are guilty of driving absolutely everywhere, even very short distances. I keep telling you that you should walk or cycle to Northbridge junction and it would make you even fitter than you are now. You drive to your bushwalking sites, which is understandable but a bit contradictory. In Boston I don’t own a car and I cycle everywhere, like most people my age around here. Otherwise I catch the bus or subway.
* We have a big house in Northbridge which is pretty empty – its sheer size has a large environmental, not just carbon, footprint.
* You use hot water for clothes washing. I think that’s unnecessary. Here I always use cold water, and my clothes are just fine – perhaps they even wear out more slowly since they aren’t exposed to hot water as much.

CONCLUSION
Dad, I don’t mean to be rude or to 顶嘴, and I know you are my Dad and I respect you very much, but I am old enough to stand very firmly on my arguments here. Maybe if you raised me in Malaysia or China I would be more obedient! But sorry, you raised me the way I am now … and I will continue to skydive as long as it is safe and I want to.