jfitzpat

Renegade Knight, BrianSnat, et al, For most public land, there are already rules and regulations. Read literally, the rules concerning litter and dumping could be directly applied to caching. Caches are, after all, intentionally concealed, abandoned property. The courts would almost certainly see it that way if a cacher knew who had plundered or destroyed his/her cache and was seeking criminal or civil redress against the culprit. But, even if you would split the hairs differently, it does not matter. As pointed out by another poster, the land management agencies are generally given great latitude in interpretting the regulations and in devising new regulations. Depending on your point of view, this can be seen as either pointless or sensible government intervention. Snowmobiling in Yellowstone would be a good example. Presumably, there is a sensible balance between loud dirty fun, and reasonable stewardship, but no matter what the NPS does, someone will be very unhappy. Climbers can tell you that it is possible to establish a reasonable relationship with the NPS and other land management agencies. They can also tell you that places that have the worst access (ex. Hueco Tanks in Texas), usually can blame the root of the problem on a handful of folks who are absolutely certain that they have the "right" to do what they "want" on "their" land. The problem with "our" land is we don't all agree with what to do with it. That is why we have BLM, NPS, etc. in the first place. -jjf

If you live near a military facility, you might want to call a flight service center and ask about any "GPS Notams" and "RAIM availability" for your intended location and time. The former will tell you if Uncle Sam is practicing something weird (been a lot of that around here lately) and the latter will tell you if good sat positioning is expected for the time/location you designate. -jjf

I Follow Road is alive and well here in the western US. Normally aspirated GA planes don't generally have the power to climb much above the MEA of most low level IFR routes, and the MEAs are often right at the primo icing level in the mountains. Running relatively low (1500-2000' above the terrain) and following roadways is pretty common. Roads often follow the lowest path through mountainous terrain, and the road gives you an emergency landing area, which can be pretty scarce in the mountains. On the subject of military and GPS, I saw a Notam today warning pilots that GPS signals would be unreliable within a considerable distance (300 nm at some altitudes) of China Lake base today. I did fly today, but headed south to San Diego and didn't notice anything on the panel mount GPS. A few weeks ago there was a Notam about possible radio interrupts near one of the Restricted areas between LAX and SAN. Again, I didn't notice any problem with radios/avionics, but I did see a Tomcat screaming along about 50-75' off the ground. -jjf

Crutch, I'm actually a little surprised. I've had pretty good luck getting reception in low wings, like a Beech Travelair or Bonanza, but I've always had to either tuck by the window or use a remote antenna with various handhelds in highwings. Haven't tried it in a Cardinal, but in quite a few (172RG, 182RG, Skyhawk, Skylane, Stationair, Centurion). Like you, I use it for backup, but I like to get traces to view in MapSource (or fly in Flight Simulator). -jjf

I suspect that threads like this would sound a lot more rational if participation was limited to people who have friends and loved ones in harms way, or are in harms way themselves. As my father used to say, "The only principles a man really stands for are the ones he stands up for when it really costs him something." Though, I must admit, I'm a big fan of biblical precedent for moral actions. For example, how about that Lot fellow offering up his two (supposedly) virgin daughters for the amusement of an angry mob (Genesis 19)? It is handy to know that "Do what you want to the girls but leave me alone!" is the kind of conduct that leads to one being saved by direct, divine intervention. Seriously, one can justify almost anything with scripture. Many Christians use Sodom and Gomorrah as biblical precedent for persecuting homosexuals (though the anti-homosexual bent is largely translation and interpretation). Yet, I don't hear many of those same Christians citing the same verses as a precedent for drunken incest (when your wife is a pillar of salt, what's a man to do?) For what it is worth, I do not understand the administration's urgency regarding Iraq. North Korea, Iran, and extreme groups like Bin Laden's would seem to be more pressing concerns than a secular tyrant like Sadam (remember, being a nice, self-absorbed, non-religious, greedy tyrant is why we gave him money and arms before '91). That said, I don't have any sympathy for the French. True, politicians seldom get a chance to toady to big business and curry public favor at the same time, but enough already. Everyone concedes that the only reason that there is any progress with inspections is the threat of the US fist. Defuse the fist, and inspections are useless. But hey, as long as the cheese monkeys get their oil... -jjf

FWIW, Small planes usually use plexiglass windows. I've never had trouble with a Vista tucked to the side of the dash on a high wing general aviation plane. Under wing is always very bad. The wing not only is metal, it usually has fuel cells and other obstructions in it. Also, there is usually a pair of VHF ant. right over the cabin, which can generate a surprising about of RF interference. GPS ant. are often mounted right in between them, with a little shielded ring. -jjf

If you enter known barometric readings, it is very accurate (I've frequently compared the Vista altimeter to barometric altimeters in planes). However, it does not take much change in barometric pressure to effect readings. A 1" change (ex. 29.92" to 30.92") is about 1000' change is indicated altitude. The altimeter also does not seem to correct for non-standard temperature and humidity (most barometric altimeters aren't). Usually, these errors are relatively small, but they can account for hundreds of feet in extreme cases. I've always found the auto calibrate to be pretty useless. I usually either calibrate from GPS, a known elevation, or get the current barometric pressure for an area from a FSS or a website like adds.aviationweather.gov. One problem with auto-calibration is altimeter loses some of its usefulness as a weather instrument. I do wish you could chose which alitude information to store in tracks our output NMEA (GPS or altimeter). Actually, maybe you can now, I'm always behind on firmware (if it ain't broke...) -jjf

The Platinum compass is not (according to the Magellan specs) particularly accurate to begin with. I've seen many Magellan units get wonky right around the freezing level, so it does not surprise me that you are getting dubious results in cold weather. A basic Silva Ranger (sort of the 'standard' for a good basic compass) is rated to something like 20 or 30 degrees below 0 (F). Most good instruments will have a similiar operating range. -jjf

Most hikers go south to north, ideally trying to travel with spring. There are stacks of books on the AT trail, but the one I would recommend is Ray Jardine's book on the PCT. Ray is unquestionably insane, but there are some real gems in his madness, and one consistant point in the "Ray Way" is LIGHT. 2,200 miles on foot is a loooong way. The peaks on the AT are modest, but they are almost beyond count. In the 100 mile wilderness in Maine, you'll be lifting your pack over your head and wading, then using your hands for class 3 scrambling before your pants are dry. It will really help if you strip your pack down to the absolute minimum. They only other thing I can suggest is a practice run or two. The John Muir Trail in California is just over 200 miles long, and hits some serious peaks in the sierras. With Yosemite and Sequoia at the ends, it is a nice vacation. It also can give a good taste of distance backpacking. One problem with the AT is it is hard to get on and off of, especially at the ends. And, based on the dropout rate, it isn't for everyone. I would definately recommend a 200-300 mile hike be attempted before going to all the effort and expense to try the AT. Good Luck, -jjf

No, the coordinates are degree.decimal. Basically, degrees and base 10 fractions of a degree. Degree, minute.decimal is usually shown with a space or a line: 34 10.335 34-10.335 Same with Degree, minute, second.decimal: 34 10 20.1 34-10-20.1 Datum is usually printed on the legends of maps. You can also get a list of all current USGS quads, publication date, and datum on the USGS website. -jjf

According to the manufacturer's specs, the Magellan compass is actually less accurate. But, as noted, more forgiving on unit orientation. -jjf

FWIW, I don't generally stare at either a compass or a GPS. I periodically take a look, get my bearings, select a visible landmark, and head for it. If I was constantly looking at map, GPS, compass, etc., I wouldn't get much enjoyment out of the trip. I also wouldn't be able to keep an eye out for drunken morons in hunting caps... -jjf Unrelated to Alan2, thanks. I do try to check out the forums once in awhile, but life has been (happily) hectic for awhile.

Like Anders, I wouldn't trade my trusty Vista for anything currently out. But, if your activities are not especially physically active, I'd go for the 76s. If nothing else, you can stick an external ant. on it and use it in a car, plane, or boat. But still, the unit isn't so bulky that it is not practical to use as a handheld for day hiking. -jjf

Despite the intense brand loyalties, I'd say that the real answer is, "it depends". Both units have their strength's and weaknesses, and just how important they are depends on your individual preferences and needs. Backpacking, hunting, backwoods camping, mountain climbing - the eTrex line is hard to beat. Light, durable, and good temp range. Driving in a vehicle, Magellan has some real advantages. It is suited to one finger operation and the screen, though a lot lower in resolution, is physically a little bigger. BOTH have screens that are too small (IMO) to safely stare at in a car, but the Mag's is a little less so. If you are going to spend most your time using your unit in a vehicle, expand your choices to include units with external ant. connecitons. Patch, quad helix, etc. debates notwithstanding, no built in ants. work that well inside SUVs or high wing airplanes. If you are really into the mapping, SD cards on the Magellan's are hard to beat. Loading 24 megs via serial is undeniably tedious. Do keep in mind that neither unit offers mapping that can realistically replace printed maps for many people. The resolution is low (about 1:100000), and you're staring at a buisiness card sized screen no matter how you slice it. If, like me, you've reached the bifocal stage in life, take a good hard look at the screens. I find the lower resolution screen of the Magellan madening at the distance I can read it (ever closer distances from my face), but I have a friend who is going to need longer arms soon who has trouble using the Vista screen. Now, I'm sure you'll get testimonials disputing everything above ("I can get a solid lock in my SUV with my XXXX, on a comet outside the orbit of mars..."), but the bottom line is most purchasers are pretty happy with either unit. Pick the one you like, and enjoy... -jjf

Eraseek, If you are interested in some of the articles, I'll dig them up. There is quite a bit of stuff on atmospheric errors on the FAA sites as well. The FAA's primary interest in WAAS is vertical accuracy, hopefully allowing GPS receivers to be used for IFR precision approaches, but some interesting material has been collected while non-precision RNAV (GPS) approaches are established and test flown. As for -30 on a Garmin, I've never been able to get one to operate at all reliably below about 0 to -5, even with Lithium batteries. -30 is well outside the rated spec for many of the components inside, so I suspect that solid operation at such temperatures is the exception, not the rule. -jjf

Gimpy, By that reasoning, why take a GPS receiver at all? My Silva Ranger and a quad map have never failed me, require no batteries, work when it is colder, and can double as tinder and a signal mirror to boot. But, a GPS is very convenient, works well in the dark, and offers fairly precise distance measuring equipment. As Anders indicated, a compass can make the device more convenient still. A built in compass directly addresses the receiver's need to infer heading based on positional sampling. Just like mapping is no real substitute for a decent printed map, a 5 or 10 degree accuracy electronic unit is no substitute for a good, seperate compass. But both can make a GPS more convenient and, I think, a little less prone to human error; since cross referencing instruments is not always easy for some people. -jjf

Eraseek, it is a lot more than batteries. The electrical properties of many components change with temperature and humidity. The idea that it is the receiver, and not the signal was precisely my point. Although I did note that sat. pos. and terrain is usually the culprit, weather is not always benign. High level inversions (non standard lapse rate) in the troposphere can have a pretty significant impact on signal accuracy. There is actually an article on this at the JPL web site. I'm not sure what your definition of a whiteout is. I've seen lots of units crap out between 0 and freezing, so severe winter conditions probably aren't a valid test for many receivers. Both Bendix King and Garmin aviation units are clearly effected somewhat by precipitation static and structural icing, but again, those issues probably are not applicable to handhelds. I've seen Magellan and Garmin handhelds lose lock in heavy upslope fog several times. But, in mountain terrain, lock can be pretty tenuous to begin with, so it is hard to say, definately, that the fog was specifically to blame. One thing to keep in mind is that, although they are resistant to certain types of attenuation and interference, GPS signals are still pretty weak. Anything that brings up the noise floor in or around the receiver can potentially have an effect. -jjf

There was another thread about this and many folks were at pains to point out that the frequency selected was picked expressly to minimize weather impact, etc. Supposedly, conditions in the troposphere (pretty much where all the weather we experience is) only effect accuracy to about the tune of 1 meter. Clocking error combined with variation in the ionosphere reportedly account for something like 6 or 7 times as much. But, all this does miss one point. We are talking not just about signals and theoretical errors. We are also talking about low cost, lower power, consumer grade receivers. My personal observation is that the handheld receviers are definately effected by cold, humidity, and EMI, perhaps to the tune of 10-15 meters. That said, I usually find that terrain and sat. position plays a much bigger role. When you use a GPS to make an instrument approach in a plane, it is not unheard of for there not to be enough birds in sight for the receiver to give an adaquate lock (the receivers have to support something called RAIM). It is a big enough deal that you are encouraged to check in advance on sat positioning for a particular date, time, and location. -jjf

FWIW, using decimal degrees vs. degrees, minutes, decimal minutes is not really a difference in precision, just in base units used. You can confirm this for yourself, use Markwell's method, or the online conversion utility at http://www.jeeep.com Then plug all the formats (ddd.dddd, dd mm.mmm, dd mm ss.sss) into the Map Maker on http://www.lostoutdoors.com and compare the markers placed on the aerial image. -jjf Ooops - I should have refreshed before hitting post - after letting the message sit on my desktop for a bit, I missed Lyra's response!

Mountain biking, kayaking, hiking, rock climbing, backup navigation in an ancient Beech V-tail and, of course, stalking Anders so I can steal the suit and rule the world... -jjf

FWIW, the -5 F pretty much matches my experience with various Garmin eTrex units. I've had my Vista die at about -10 F (lithium batteries). After that, the thermometer in my whistle bottomed out and the fluid in my Silva compass got slushy. I was so relieved to find a good ledge for my Stephenson tent, I actually forgot the Vista outside and had to chip it out with an ice axe in the morning. The moral, of course, is Gu tastes repulsive warm, cold, or frozen... Although they are fine units, I have never had much luck with Magellan's in the cold. I've seen a 315 (320?) konk out around 32 F and a Meridian freak out just under 40 F (it actually came back to life when the memory card was removed). -jjf

I can't help but think - even one lantern battery is the weight of a heck of a lot of AA's... I must be the only person alive who actually gets 10 or so hours of operation out of my Vista! -jjf

As noted above, NAD27 is primarily used for Topozone. The GNIS database is inconsitant. Much of the database uses NAD-27 coordinates. But, like Topozone, the use is not universal. GNIS positions are also often off a bit anyway because they are often taken from printed reference materials. The Space Needle would be a good example. If you look on an aerial photo the spot seems to clearly miss the building, but if you look at the USGS topographic map, the dot is placed squarely on the buildings next to the label. I've converted all the GNIS FTP files to WGS-84 and placed them online in a searchable format. Drop me a note if you are interested. It's free, but saying the site name is apparently grounds for moderation of my messages... -jjf

Just a reminder, when using Topozone, use NAD-27 as your map datum for best accuracy (otherwise, you can be a couple hundred yards off). When you use USAPhotomaps, LostOutdoors.com, etc., NAD-83/WGS-84 is expected. This is the default on most receivers. -jjf

Yes, some industrial and military receivers are considerably more accurate than consumer handhelds. The FAA, who has a big interest in WAAS, has some links on the subject. -jjf