hackish

I can really only comment on a PA-31. It has a somewhat low tail. Jumprun is about 100 (blue line) with 15 flaps. Climb is at 125. This changes the pitch significantly. Every jumper consumes 12.5l of fuel or about 4ga to get to 13.5. So in theory letting a H+P out saves about 2.5ga on the subsequent climb. Total amount of time to config the AC for a H+P is about 2min from pulling power to resuming climb. In the case of our DZ the efficiency gains are more in engine management (cooling some TIO-540s properly takes care) and efficiently planning the ascent and descent. The aim is to achieve the jump altitude just in time to config for jumprun right over the spot. Some simple tasks and speed management at the top can get the engines well into a controlled cooldown so we can achieve 3500-4000fpm descent. If the DZO is that concerned about every last cent then make sure they're out washing and waxing the AC every week, not putting jumpers safety at risk. -Michael

Cell phones don't always make the best receivers. It would be interesting to see what sort of range you could get with a better antenna. Maybe that would solve the range issue. -Michael

I've been seriously considering the same. Best advice I got was to just go attend the senior rigger course in the USA and do it like the rest of the students. Although the Canadian system is being revamped, the process for becoming a Rigger B appears to be nearly impossible. -Michael

I did some testing with my Altitrack and a series of precision MEMS barometer sensors plus a couple of old school analog units. I believe that the digital altimeter will be most accurate over the largest range. I actually have an altimeter rigged up with a raspberry pi that can read approx 1' of altitude change. It's not very useful as it takes about 3 seconds per measurement... -Michael

I'm a big fan of a prime lens. At present I am jumping my 60D with a 24mm EF series. Much lighter than a zoom lens.

With the APS I'm shooting a prime 24. Full frame I've got a 20mm prime as well. Both are canon glass. I prefer the smaller size and weight plus they seem to have a certain crispness you just can't get with the 17 or whatever elements of glass in a zoom lens. -Michael

I'll second that one. Until we got rid of the last FXC's at my DC there was a constant stream of them going back and forth for their maintenance. As others have said, any AAD will do. If you think with statistics not emotions the chance of an AAD failing or misfiring is so small that any one will improve your safety. -Michael

I've shot stills with my 5D a few times when I felt brave. It's pretty heavy for my poor neck but honestly photos of the last load of the day were a zillion times better... -Michael

It's a neat idea but unfortunately skydivers are an emotional bunch. If you ever read one of the zillion I only jump this AAD because threads you will know this. The chance of failure of any of the AADs already on the market is so tiny you could mention it in fractions in a million jumps. The first time there is a failure, even someone pressurizing a plane or setting the unit incorrectly you can expect your product to be thrown under the bus. The story will subsequently be retold with a variable rate of accuracy for years every time someone who purchased a different AAD wants to justify why theirs is better. Periodic maintenance is a really good idea from a business point of view. You will have a good stream of income and as improvements come along and defects are found you can secretly switch out the faulty components. If I had to put bread on the table with AAD sales I'd want them coming back every 4 years for a check. -Michael

Thanks everyone. I'm trying to find another mechanic. There seem to be only 2 in my city and they both have the same opinion about the machine. I think I may have to pack the machine up and travel to Montreal to find someone decent. I'm also wondering if somehow they're assuming that the machine is a home machine because as soon as I mention size 69 thread their ears shut off. -Michael

I did my research and spoke with many people before purchasing a 20U. I got an almost new unit but it really does need some adjustment to properly sew e-thread. So I consulted with an industrial sewing machine guy about a tuneup. He said the 20U is entirely the wrong machine to sew e-thread. Tensioning isn't designed for that weight of thread, the hook can't be setup or adjusted properly and it's going to be dropping stitches at best. I spoke with someone different who said basically the same in not so many words. My experience hasn't been so great with this machine and it is dropping stitches and tension is really tough to get right... Thoughts? Is it really the wrong machine or do I just need to find a better mechanic? -Michael

Same thing happening here, one of the rigs has a collapsible slider so it is favoured by the TMs. An interesting solution we riggers came up with is to check the total number of jumps on the AAD to determine how many jumps have been done on each set of equipment. -Michael

I don't quite understand why so many people view the katana as a suicide machine for all but the most experienced. Like any high performance canopy you have to fly the openings but less than others I've jumped. I quite like the openings. I'm only mildly interested in swooping but happen to like the way it handles and flares. I usually fly mine on camera jumps and at most they get a harness turn for landing. I think the best choice would be to demo each and make the decision based on how you feel. Let's face it you wouldn't buy a car without a test drive first would you? -Michael

Every year I go to Florida to jump. Even between Canada and the USA there is a very noticeable difference in the size of people. I have been a type1 diabetic for about 20 years so I have a good handle on what I eat. The food in the USA has more calories and the portion size is much larger - I'm full off kid sized portions. Next time you're in the grocery store and see a morbidly obese family have a look at what's in their cart. Even without the required exercise I'm sure they'd be much smaller and healthier if they ate proper meals. If you hope to reverse some of this trend then someone will have to start educating the people on how to properly feed themselves. Don't expect the grocery store to do it - I don't think the margin is very good on a jug of milk and a bag of carrots... The system is flawed on so many levels. -Michael

There must be some reason ropes & rings fell out of fashion years before I started skydiving... Maybe the OP can make a reefing system using magnets or velcro. You know, velcro all the attachment units together to reef the canopy... I believe there was an accuracy canopy using nylon re-enforced attachment points like the OP describes. Sort of a micro-version of what I think he's got in mind... Albeit I don't think they used them for the same purpose. Can't remember what they called those things? eiffs maybe??? I'm sure Rob knows. -Michael

I too have packed a couple of Falcons a few times. It seems that these oddball canopies crop up in bunches. If I had to guess years ago one jumper bought one and convinced a number of others at the DZ to do the same. Sometimes I do wish older gear would be retired. -Michael

Exactly right - rigger induced bulk problem... I have the same rig. First time I packed it it suffered the same problems. Next repack I reduced the bulk and the flaps stay where they should. I find the trick is to be neat with the ear folds. Some riggers just ram them in the bag all scrunched up but if you make neat folds the rig is much neater. -Michael

To the OP: How about simply using a rigger local to the buyer to escrow the transaction. It is a fairly common thing in these parts. The canopy arrives, I inspect it for the buyer, they pay me (cash) I release the canopy and disperse the funds to the seller. The skydiving community is small enough that it's not too hard to find someone you know who knows the buyer/seller. -Michael

We just replaced a drogue with a replacement UPT unit last weekend. Many of the wear items have been redesigned and the bridle is no longer made of kevlar. I'm rather resistant to the idea of replacing a part of a tandem system with a non-manufacturer part. -Michael

I mentioned the LZW thing because I have a C&D from it many years ago. The patent itself is titled "Data Compression Method". It's been a lot of years since I looked at it but having been through the patent docs a number of times it definitely described the method (algorithm) not an apparatus. I got the C&D because I implemented it in assembly language and built one of the fastest GIF decoders at the time (yay 8086 processors). Patent 4814746 even had some source code in it. I'm not a patent lawyer but from my point of view algorithms can definitely be patented. -Michael

I'm not a patent lawyer but there are a number of examples where algorithms have been patented and enforced over the years. In the computer world, check out the RSA algorithim (encryption) or LZW (data compression). One prime example was the .gif file format where many programmers were successfully forced to pay royalties for their software that used the LZW compression to create .GIF files. MEMS pressure sensors can be extremely accurate. I have one that I've repeatedly used to show a 2' pressure change (going up and down stairs). Of course it was also highly affected by changes in barometric pressure. Despite the costs there are advantages to requiring service every 4 years. Let's face it, we skydivers won't send our vigils in for checkup/maintenance if they don't require it. Hardware and algorithms can and have been updated. If you recall an issue a few years back where a factory was told that their batch of pressure sensors may have been faulty the possibility then exists to swap them out next 4 year maintenance without ever having to inconvenience the jumpers. It is definitely possible to get the algorithm out of any AAD. That's what I do for a living, reverse engineer firmware. It's only a matter of time and money... lots of it. One could definitely work with rate of change to determine if the AAD has truly entered freefall or if they "accelerated at an impossible rate". Don't forget the longer you wait to make the decision the more chance that the user is going to die should they really have exited the aircraft. Is anyone aware of a fatality where the jumper left below activation altitude and their Cypres didn't fire? How about a save on a Vigil in the same circumstances? It's a tough argument to make either way. -Michael

1. Where did you come up with this value? 2. And at what speed would you expect this value to appear? The reason for the "or so" is that it is a ballpark value to give the reader a feel for the idea being communicated. If the intent was to provide a calculated value with some precision the wording would have reflected that. http://www.youtube.com/watch?v=04-wne9QL2E&t=1m20s As an example on a different rig, deployment occurs after the pilot chute passes over the shoulder to reach full extension but not before the jumper rolls over from the back to earth position. -Michael

I was going to mention something like that as an add-on to RiggerLee's comments! While some manuals do provide useful tips and emphasis, I've even had a new rig come packed fresh from the factory, in a way contrary to the manual. "Secret stuff" becomes like some little status contest among riggers ("I can pack that rig tighter than you can! Bet my loop was 1/4" shorter!"), rather than allowing an average but committed rigger to provide a safe pack job for the customer that doesn't unduly stress the rig. I think part of the issue is that many rig manufacturers are not able to invest a lot of money in keeping their documentation up to date. Every year I try to hit up a different manufacturer and ask their riggers to show me the tricks to packing their rigs. Seldom are these tricks in the actual manual. The manual is written or updated from a previous design and the rig goes into production. After assembling and packing 500 rigs the staff riggers find/invent these little tricks but there is seldom the time and money to go back and revise the manual to publicize these little things. Back on the original topic many of the rigs out there won't let the reserve out if you're stuck in a back to earth configuration. One would expect the 100lbs or so of drag from the reserve PC to roll the skydiver over but not always. -Michael

Obviously as others have said go talk to the rigger and slap him a few times. For sure after a goofup he'll be more careful. Every good rigger is very careful but even the best occasionally do have a brain fart. Yes, I know a rigger should never make a mistake, nor should a pilot, doctor or rig manufacturer but it can happen. I his packjobs make you feel uncomfortable then switch riggers. -Michael

Unfortunately many skydivers are emotional thinkers who make emotional decisions not necessarily backed by science or true facts. Stories get told, mis-quoted and around they go eventually told as fact. I would suggest that you contact the manufacturer of each product and pose your questions to them. The manufacturer and dealer will be the best educated to help you make your decision. Every AAD out there has had some sort of failure. At the end of the day all the approved AADs are quality products with dedicated teams of individuals working very hard to ensure they are as safe as they can build them. Different AADs have different features and different firing criteria. Some require you to take your rig offline for maintenance, some do not. If you bail at 1300' some AADs will not have armed and will do nothing, others arm at 150' and could provide protection. At the end of the day an AAD is about your life. That unlikely event where you need it. Ask the questions and decide for yourself which product is more appropriate to make you feel comfortable. -Michael