labrys 0 #1 December 8, 2006 The last jump I made my audible alarms all went off about 1500 feet higher than they were set for. I was filming someone tracking at 6000 when the first went off so I checked the ground and my wrist and shrugged it off. The alarm that should have gone off at 2500 went at 4000, and my dirt alert went off while I deployed (that was a creepy sound) Anyway. It was the third or fourth jump of the day and we left at about the same spot as the previous jumps but ended up a good half mile downwind of where we wanted to be on this load. Someone suggested that a big barometric pressure change / weather change might account for the audible acting this way and could have been accompanied by a big change in the speed of the uppers. Is my leg being pulled?Owned by Remi #? Quote Share this post Link to post Share on other sites
jtval 0 #2 December 9, 2006 NO leg pulling. ever notice that sometimes when you go to the DZ your alti is not set at zero? When you left the previous weekend it was, so why would it change? Barometeric pressure. as far as I know the audibles work the same way...so does your AAD. Go read about the 300(or was it 400?) way in thailand last year. you'll see that there was a plane that had some pressure problems and a BUNCH of AAD's fired. As far as I know the way the AAD's compensate for the change is that they take a pressure sample a bunch of times per second. I dont know the FIGURES but that's the theory of itfromwhat I understand.My photos My Videos Quote Share this post Link to post Share on other sites
Eule 0 #3 December 9, 2006 QuoteThe last jump I made my audible alarms all went off about 1500 feet higher than they were set for. [....] Someone suggested that a big barometric pressure change / weather change might account for the audible acting this way and could have been accompanied by a big change in the speed of the uppers. It sounds plausible. Adjust an analog wrist altimeter so it says 0 on the ground and put it on the table. Look at it tomorrow and it probably won't be pointing at 0 anymore. Pilots don't usually set their altimeters to 0 on the ground (maybe a floatplane pilot on the ocean would), but they do dial in the current barometric pressure on the ground so their altimeter will read right. I think some digital/audible altimeters and AADs will adjust themselves for reasonable variations in pressure on the ground. Other digital/audible altimeters might only measure the ground-level pressure when you first turn them on, so if the weather changes on the ground, you might have to power-cycle the altimeter to get it to indicate correctly. Read the manual for your altimeter - it should say. When and where was this? I ran the numbers for AerOhio last weekend and the altimeter setting hit a low on Friday morning and then climbed fairly stedaily until noon Saturday, then it more or less leveled off. Rising pressure would make a barometric altimeter think it was at a lower altitude than it actually is, which is consistent with what you saw. EulePLF does not stand for Please Land on Face. Quote Share this post Link to post Share on other sites
happythoughts 0 #4 December 9, 2006 About a month ago, I did 3 jumps. On the 4th, my audible went off at 8K and flat lined at 3 or 4. Really obnoxious. I think that I bumped a set button while on the plane. Quote Share this post Link to post Share on other sites
pilotdave 0 #5 December 9, 2006 I don't believe a change in barometric pressure could cause that. A change that fast would affect everybody's altimeter, including the airplane's. It would also fire every AAD on the load and would probably cause cows to fly or something like that. I can believe that a local pressure change inside your helmet might have confused your audible, or an internal malfunction of some type. Dave Quote Share this post Link to post Share on other sites
labrys 0 #6 December 9, 2006 QuoteI don't believe a change in barometric pressure could cause that. A change that fast would affect everybody's altimeter, including the airplane's. It would also fire every AAD on the load and would probably cause cows to fly or something like that. That was what I thought too.Owned by Remi #? Quote Share this post Link to post Share on other sites
popsjumper 2 #7 December 9, 2006 Next time you're at the store getting batteries for your "toys" get 'em for your alti also. J/K...I have no earthly clue why your alti did that. I could only suggest re-setting the ground zero. For my Neptune it's "IM on DZ" or something like that.My reality and yours are quite different. I think we're all Bozos on this bus. Falcon5232, SCS8170, SCSA353, POPS9398, DS239 Quote Share this post Link to post Share on other sites
BIGUN 1,297 #8 December 9, 2006 Perhaps you could share this information with the manufacturer and follow up the thread by letting us know what they think? I'd be curious also. While the baro scenario could have some bearing, I'm more likely to agree with Andy (POPS) and go with battery.Nobody has time to listen; because they're desperately chasing the need of being heard. Quote Share this post Link to post Share on other sites
labrys 0 #9 December 9, 2006 A few others have commented that barometric changes can and do happen. From one day to another I understand that. I'm asking about a very sudden change from one load to another. I'll email the manufacturer of the audible involved to ask their opinion.Owned by Remi #? Quote Share this post Link to post Share on other sites
Calvin19 0 #10 December 9, 2006 1500' is a big change for an hour long period. you would probably see the actual front moving over you for that. Quote Share this post Link to post Share on other sites
pjc 0 #11 December 9, 2006 1500' is 50 millibars of pressure change, thats just about the highest area of high pressure to the lowest low. 3mb of change in 1 hour would be considered a very steep pressure gradient. If theres 1500' of change in 1 hour, its not going to be down to change in atmospheric pressure (sorry, don't know figures in Hg) IMHO of course Quote Share this post Link to post Share on other sites Calvin19 0 #12 December 9, 2006 hence the sarcasm Quote Share this post Link to post Share on other sites JohnRich 4 #13 December 10, 2006 QuoteA few others have commented that barometric changes can and do happen. From one day to another I understand that. I'm asking about a very sudden change from one load to another. I don't think that can happen. An atmospheric pressure change over a day or two can make a difference of up to about 500', but I've never seen it change by 1,500'. That big a change in that short a time period would be like if a hurricane blew thru - and then you wouldn't be skydiving. I think it's more likely that you bumped a button at 1,500' on the climb to altitude which reset the ground level zero setting. Quote Share this post Link to post Share on other sites Zing 2 #14 December 10, 2006 Sounds to me like one of those gremlins lurking in the airplane hitched a ride in your gadget. Could be a one-time anomaly, or the first indication that your audible altimeter is going south. On the other habd, sometimes those gremlins just go away and are never seen, or in your case, heard from, again. Gadgets are nice luxuries, but not a substitute for your eyeballs and time sense.Zing Lurks Quote Share this post Link to post Share on other sites iluvtofly 0 #15 December 10, 2006 May I ask what audible it is that you are using? I'm not asking to soil the name of the company. I'm just curious because I only recently got my A lisence and just bought my first audible. So obviously this thread has me asking many questions. Quote Share this post Link to post Share on other sites MrBrant 0 #16 December 10, 2006 when did you last change the betteries? Quote Share this post Link to post Share on other sites labrys 0 #17 December 10, 2006 QuoteMay I ask what audible it is that you are using? I'm not asking to soil the name of the company. I'm just curious because I only recently got my A lisence and just bought my first audible. So obviously this thread has me asking many questions. It's great that you're asking questions, but I do not wish to disclose the type of audible it is because I think that's unfair to the manufacturer. I was looking for comments about whether such an anomly could be attributed to sudden baromteric changes and that's all. I've emailed the manufacturer to ask their opinion and advice. The many suggestions that I change the battery are good ones. I'll change it after I hear from the manufacturer in case they'd like to take a look as it "as-is." It's only an audible and I trust it as much as an audible deserves to be trusted. It's not a life-saving piece of gear, it's just a nice reminder and I'm not stressed about it at all.Owned by Remi #? Quote Share this post Link to post Share on other sites labrys 0 #18 December 10, 2006 I don't remember Owned by Remi #? Quote Share this post Link to post Share on other sites pilotdave 0 #19 December 11, 2006 If it happens to be a neptune, a field service member can actually download the data from the jump and send it to alti-2 to see for themselves for troubleshooting. If it's a hardware issue, they should be able to figure that out. Dave Quote Share this post Link to post Share on other sites Eule 0 #20 December 14, 2006 QuoteI was looking for comments about whether such an anomly could be attributed to sudden baromteric changes and that's all. Some Googling is finding all kinds of lists of record high and low barometric pressures, but I haven't found much on records of how fast the pressure has changed. Some sites do archive METARs (aviation weather observations) and if you can give a date, time, and location, the actual pressure change at a nearby location can be looked up. Maybe a pressure change corresponding to 1500 feet just flat doesn't happen outside of a tornado, but it's still fairly easy to find out how much the pressure actually did change at your location. If the manufacturer says that low batteries can cause a wrong reading, it might be interesting to check the open circuit and under load voltage of the present set of batteries. If these are a lot lower than the voltages from the same tests on a fresh set of batteries, then the batteries are probably the problem. The other approach is simply to put in new batteries and see if the problem goes away, but if it's an infrequent problem in the first place, you have to run a lot of tests to be sure the problem is gone. What would really be interesting is to hook up a variable power supply in place of the batteries, stick the audible in a pressure chamber with a calibrated gauge, and take it for some rides up and down at various supply voltages to see what happens. Variable power supplies are pretty easy to get but pressure chambers with calibrated gauges are a little bit harder to find. :) The altimeter manufacturers have them for sure but it can be educational to do the experiment for yourself. EulePLF does not stand for Please Land on Face. Quote Share this post Link to post Share on other sites labrys 0 #21 December 16, 2006 QuotePerhaps you could share this information with the manufacturer and follow up the thread by letting us know what they think? I'd be curious also. While the baro scenario could have some bearing, I'm more likely to agree with Andy (POPS) and go with battery. I forgot to update this, sorry. I sent the manufacturer an email on a Friday night and got an answer Saturday morning. I didn't expect such a fast reply. According to them, low battery voltage won't cause this behavior (it happened on a second jump, BTW). They recommended turning the altimeter off (it's been in econmoy mode) and back on and returning it to them for service if it misbehaves after that.Owned by Remi #? Quote Share this post Link to post Share on other sites Join the conversation You can post now and register later. If you have an account, sign in now to post with your account. 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Calvin19 0 #12 December 9, 2006 hence the sarcasm Quote Share this post Link to post Share on other sites
JohnRich 4 #13 December 10, 2006 QuoteA few others have commented that barometric changes can and do happen. From one day to another I understand that. I'm asking about a very sudden change from one load to another. I don't think that can happen. An atmospheric pressure change over a day or two can make a difference of up to about 500', but I've never seen it change by 1,500'. That big a change in that short a time period would be like if a hurricane blew thru - and then you wouldn't be skydiving. I think it's more likely that you bumped a button at 1,500' on the climb to altitude which reset the ground level zero setting. Quote Share this post Link to post Share on other sites
Zing 2 #14 December 10, 2006 Sounds to me like one of those gremlins lurking in the airplane hitched a ride in your gadget. Could be a one-time anomaly, or the first indication that your audible altimeter is going south. On the other habd, sometimes those gremlins just go away and are never seen, or in your case, heard from, again. Gadgets are nice luxuries, but not a substitute for your eyeballs and time sense.Zing Lurks Quote Share this post Link to post Share on other sites
iluvtofly 0 #15 December 10, 2006 May I ask what audible it is that you are using? I'm not asking to soil the name of the company. I'm just curious because I only recently got my A lisence and just bought my first audible. So obviously this thread has me asking many questions. Quote Share this post Link to post Share on other sites
MrBrant 0 #16 December 10, 2006 when did you last change the betteries? Quote Share this post Link to post Share on other sites
labrys 0 #17 December 10, 2006 QuoteMay I ask what audible it is that you are using? I'm not asking to soil the name of the company. I'm just curious because I only recently got my A lisence and just bought my first audible. So obviously this thread has me asking many questions. It's great that you're asking questions, but I do not wish to disclose the type of audible it is because I think that's unfair to the manufacturer. I was looking for comments about whether such an anomly could be attributed to sudden baromteric changes and that's all. I've emailed the manufacturer to ask their opinion and advice. The many suggestions that I change the battery are good ones. I'll change it after I hear from the manufacturer in case they'd like to take a look as it "as-is." It's only an audible and I trust it as much as an audible deserves to be trusted. It's not a life-saving piece of gear, it's just a nice reminder and I'm not stressed about it at all.Owned by Remi #? Quote Share this post Link to post Share on other sites
labrys 0 #18 December 10, 2006 I don't remember Owned by Remi #? Quote Share this post Link to post Share on other sites
pilotdave 0 #19 December 11, 2006 If it happens to be a neptune, a field service member can actually download the data from the jump and send it to alti-2 to see for themselves for troubleshooting. If it's a hardware issue, they should be able to figure that out. Dave Quote Share this post Link to post Share on other sites
Eule 0 #20 December 14, 2006 QuoteI was looking for comments about whether such an anomly could be attributed to sudden baromteric changes and that's all. Some Googling is finding all kinds of lists of record high and low barometric pressures, but I haven't found much on records of how fast the pressure has changed. Some sites do archive METARs (aviation weather observations) and if you can give a date, time, and location, the actual pressure change at a nearby location can be looked up. Maybe a pressure change corresponding to 1500 feet just flat doesn't happen outside of a tornado, but it's still fairly easy to find out how much the pressure actually did change at your location. If the manufacturer says that low batteries can cause a wrong reading, it might be interesting to check the open circuit and under load voltage of the present set of batteries. If these are a lot lower than the voltages from the same tests on a fresh set of batteries, then the batteries are probably the problem. The other approach is simply to put in new batteries and see if the problem goes away, but if it's an infrequent problem in the first place, you have to run a lot of tests to be sure the problem is gone. What would really be interesting is to hook up a variable power supply in place of the batteries, stick the audible in a pressure chamber with a calibrated gauge, and take it for some rides up and down at various supply voltages to see what happens. Variable power supplies are pretty easy to get but pressure chambers with calibrated gauges are a little bit harder to find. :) The altimeter manufacturers have them for sure but it can be educational to do the experiment for yourself. EulePLF does not stand for Please Land on Face. Quote Share this post Link to post Share on other sites
labrys 0 #21 December 16, 2006 QuotePerhaps you could share this information with the manufacturer and follow up the thread by letting us know what they think? I'd be curious also. While the baro scenario could have some bearing, I'm more likely to agree with Andy (POPS) and go with battery. I forgot to update this, sorry. I sent the manufacturer an email on a Friday night and got an answer Saturday morning. I didn't expect such a fast reply. According to them, low battery voltage won't cause this behavior (it happened on a second jump, BTW). They recommended turning the altimeter off (it's been in econmoy mode) and back on and returning it to them for service if it misbehaves after that.Owned by Remi #? Quote Share this post Link to post Share on other sites
