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#71
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Altimeter Question
On 2008-04-17, WingFlaps wrote:
Urban legend? O, it was not Newquay but Newlyn (both in cornwall). The datum is sea level as set the British Admiralty back then so the obvious Q code would have been QNH. Look up the history of the naval tidal observatory if you don't believe it. Source, please. The Q codes are just as Stefan said: randomly assigned. They were chosen that way so as not to conflict with any nation's callsign blocks (to this day, there are no callsigns assigned with Q as the first letter). The apparent relationship between QNH and Newlyn Harbor is purely coincidental. -- Jay Maynard, K5ZC http://www.conmicro.com http://jmaynard.livejournal.com http://www.tronguy.net Fairmont, MN (FRM) (Yes, that's me!) AMD Zodiac CH601XLi N55ZC (ordered 17 March, delivery 2 June) |
#72
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Altimeter Question
On 2008-04-17, terry wrote:
I wasnt aware you dont use the QNH term in the States. So what do you call the number you dial up to make the altimeter read airport elevation? Altimeter or altimeter setting. For example, "Fairmont altimeter two niner niner eight". In radio procedure, using Q codes in speech is technically improper, although it's done all the time (at least on the ham bands). The FAA, being sticklers for proper procedure, would naturally include this bit. There are no Q codes in use in aviation in the US any more, TTBOMK. -- Jay Maynard, K5ZC http://www.conmicro.com http://jmaynard.livejournal.com http://www.tronguy.net Fairmont, MN (FRM) (Yes, that's me!) AMD Zodiac CH601XLi N55ZC (ordered 17 March, delivery 2 June) |
#73
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Altimeter Question
On Thu, 17 Apr 2008 06:51:24 -0700 (PDT), terry
wrote: On Apr 17, 11:38*pm, Stealth Pilot wrote: On Thu, 17 Apr 2008 07:30:56 -0400, "Barry" wrote: I am confused by this practice commercial nav question. ( at least I am confused by the answer in the book which was b. but I think both a and c are correct), but I appreciate some other opinions. Day 1 Altimeter reads elevation of 1390 feet with 1013 HPa set on subscale * * * * ( thats equivalent to 29.92 inches of Hg for the US folks) Day 2 Altimeter reads elevation of 1000 feet Assuming the altimeter subscale was not changed between day 1 and day 2 it could be said that a. The QNH is higher on day 2 b. The QNH is lower on day 2 c. The pressure altitude at the airport is lower on day 2 d. *The atmospheric pressure at the aerodrome has not changed. I agree with you - answers a and c are both correct. *Day 2 QNH is about 1026. playing with an altimeter here in my lap. simulating 1390 by setting 390. the qnh reads as 1032. moving the needle lower sees the qnh values going lower. so to correct for the reduced reading I would need to move the qnh the other way.(increase it) I agree a is correct from playing with an actual altimeter. c is correct just from reading the data in the question. fwiw Stealth pilot- Hide quoted text - gday Stealth, I just think of an altimeter as being a inverse pressure guage cos pressure decreases with altitude, so for altitude reading to have gone down , atmospheric pressure has to have gone up. I gotta ask, why have you got an altimeter in your lap? Terry that's like the goon show joke. turn the knob on your side. but I dont have a knob on my side. ...there's one on the door though. anyway it is the old altimeter out of my auster restoration. it lives with a few other instruments in the cupboard behind me as I type. |
#74
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Altimeter Question
Hi,
In article , Bertie the wrote: But, like sticking to imperial measurements, I think you stand alone. What, like altitude in feet, altimiter settings in inches of mercury, distance in miles, volume in gallons? Mr. Kettle, allow me to introduce you to Mr. Pot Britain is still clinging to a number of archaic aviation terms (you still gotta know which direction to go whatever you choose to call it!) One of my favorites is the "Pan" call. Nobody uses that anymore except you guys. I had an entertaining few minutes in Germany listening to some Nigel making one of these a few years back. It went something like this. The Nigel Skipper is played Terry Thomas and the German controller by Hardy Kruger in this re-creation. Boffo Air 2234 "Rhine, Boffo 2234, PAN PAN PAN" ATC "Station calling?" BA 2234 "Rhine this is Boffo 2234, PAN PAN PAN" ATC. "Boffo 2234, pass your message" BA 2234 "Rhine, this is Boffo 2234, PAN PAN PAN" ATC, "Boffo 2234, say again?" BA2234 "Rhine, this is a PAN call from Boffo 2234" (at this point you can almost hear the Boffo skiper thinking "bloody foreigners" ATC, "Boffo 2234, are you declaring an emergency?" BA2234 "Negative Rhine, Boffo 2234 is making a PAN call" ATC, -silence- BA 2234, Rhine, we have a pasenger having a heart attack, we're mkaing a PAN call" ATC, "Boffo 2234, do you wish to declare an emergency?" BA 2234 "Nega- Oh, yes, yes, we're declaring an emergency, we'd like to divert to Frankfurt immediatly. " ATC, roger 2234, fly heading 330 and descend now to FL 150" No ****, this really happened. I think it actually took longer than this. The Brit captain just wouldn't let go.... The PAN actually sounds to me like a good idea, but as I always say I'm still a lowly stude! Being able to differentiate between a Mayday (basically aircraft in imminent danger) and PAN (something that needs priority but nothing that will endanger the aircraft in short order) seems like a good idea to me. Anyway, the formt of his PAN PAN call was all wrong according to CAP 413 That's my current bug-bear actually. The only exam I've got left to do (apart from the Skills test) is the R/T practical. On this, unless you're word perfect on the Mayday call you've failed, but what are the odds of a controller ignoring your mayday because you forgot (for example) your pilot qualifications in the mayday call? Andy |
#75
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Altimeter Question
On Thu, 17 Apr 2008 12:57:57 GMT, Larry Dighera
wrote: On Thu, 17 Apr 2008 02:20:46 -0700 (PDT), terry wrote in : I am confused by this practice commercial nav question. ( at least I am confused by the answer in the book which was b. but I think both a and c are correct), but I appreciate some other opinions. Day 1 Altimeter reads elevation of 1390 feet with 1013 HPa set on subscale http://en.wikipedia.org/wiki/Mbar Atmospheric air pressure is often given in millibars where "standard" sea level pressure is defined as 1013.25 mbar (hPa), equal to 1.01325 bar. Despite millibars not being an SI unit, they are still used locally in meteorology in some countries to describe atmospheric pressure. The SI unit is the pascal (Pa), with 1 mbar = 100 Pa = 1 hPa = 0.1 kPa. Meteorologists worldwide have long measured air pressure in millibars. After the introduction of SI units, others use hectopascals (which are equivalent to millibars) so they could stick to the same numeric scale. Similar pressures are given in kilopascals in practically all other fields, where the hecto prefix is hardly ever used. In particular, Canadian weather reports use kilopascals (which could also be called centibars). Torricelli started it all off. if you are the first guy in the world with a barometer what do you call the measure of the atmospheric pressure measured on that barometer. a bar(ometer). divide the value into a thousand to give you some nice fine numbers to measure with and you have the millibar. pascal is just a johhny come lately in pressure measurements. the poms worked out that 14.8lbs per square inch = 1 bar(ometer) Stealth ( I'm with torricelli) Pilot |
#76
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Altimeter Question
On Thu, 17 Apr 2008 14:54:53 +0000 (UTC), Bertie the Bunyip
wrote: terry wrote in news:179c2f21-99ad-4415-a9b2- : On Apr 18, 12:07*am, Bertie the Bunyip wrote: terry wrote in news:234756e2-a583-4cbc-8f42- : I am confused by this practice commercial nav question. ( at least I am confused by the answer in the book which was b. but I think both a and c are correct), but I appreciate some other opinions. Day 1 Altimeter reads elevation of 1390 feet with 1013 HPa set on subscale * * * * *( thats equivalent to 29.92 inches of Hg for the US f olks) Day 2 Altimeter reads elevation of 1000 feet Assuming the altimeter subscale was not changed between day 1 and day 2 it could be said that a. The QNH is higher on day 2 b. The QNH is lower on day 2 c. The pressure altitude at the airport is lower on day 2 d. *The atmospheric pressure at the aerodrome has not changed. It's A. It could also be C if the airfield has a serious subsidance problem. you are really confusing me now Bertie, I got learned that the pressure ht was wot your altimeter reads when you have 1013.2 in the window ( or 29.92 for you ...or maybe not cos everyone knows bunyips are aussies ) 1000 is lower than 1390 therefore pressure altitude is lower on day 2.. surely!. Yer right, of course, I just couldn't resist the joke! There's a name for that, if I'm not mistaken, and it's QNE. But theyre going for A, I'm pretty sure and made an error in what thye were trying to say in C. I'm bi-barometric, BTW. Bertie bi-barometric? is that as bad as being queer :-) |
#77
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Altimeter Question
In rec.aviation.student Andy Hawkins wrote:
The PAN actually sounds to me like a good idea, but as I always say I'm still a lowly stude! Being able to differentiate between a Mayday (basically aircraft in imminent danger) and PAN (something that needs priority but nothing that will endanger the aircraft in short order) seems like a good idea to me. Given the rarity of emergency calls, it seems like the important thing is to make the emergency known in a simple and easy fashion first, then work out the details later on as they're needed. The distinction is useful, but I think that it's not worth putting extra workload on the pilot to figure out just what degree his emergency is in his moment of crisis. -- Michael Ash Rogue Amoeba Software |
#78
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Altimeter Question
Stealth Pilot wrote:
bi-barometric? is that as bad as being queer :-) Only half the time. |
#79
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Altimeter Question
On 04/18/08 08:38, Michael Ash wrote:
In rec.aviation.student Andy Hawkins wrote: The PAN actually sounds to me like a good idea, but as I always say I'm still a lowly stude! Being able to differentiate between a Mayday (basically aircraft in imminent danger) and PAN (something that needs priority but nothing that will endanger the aircraft in short order) seems like a good idea to me. Given the rarity of emergency calls, it seems like the important thing is to make the emergency known in a simple and easy fashion first, then work out the details later on as they're needed. The distinction is useful, but I think that it's not worth putting extra workload on the pilot to figure out just what degree his emergency is in his moment of crisis. If the pilot is in a moment of crisis, then an emergency should be declared. PAN is used when it is not at that level. -- Mark Hansen, PP-ASEL, Instrument Airplane, USUA Ultralight Pilot Cal Aggie Flying Farmers Sacramento, CA |
#80
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Altimeter Question
Andy Hawkins wrote in
: Hi, In article , Bertie the wrote: But, like sticking to imperial measurements, I think you stand alone. What, like altitude in feet, altimiter settings in inches of mercury, distance in miles, volume in gallons? Mr. Kettle, allow me to introduce you to Mr. Pot I'm more of a frying pan than a kettle. And you'll notice i have not excluded americans in this thread. Britain is still clinging to a number of archaic aviation terms (you still gotta know which direction to go whatever you choose to call it!) One of my favorites is the "Pan" call. Nobody uses that anymore except you guys. I had an entertaining few minutes in Germany listening to some Nigel making one of these a few years back. It went something like this. The Nigel Skipper is played Terry Thomas and the German controller by Hardy Kruger in this re-creation. Boffo Air 2234 "Rhine, Boffo 2234, PAN PAN PAN" ATC "Station calling?" BA 2234 "Rhine this is Boffo 2234, PAN PAN PAN" ATC. "Boffo 2234, pass your message" BA 2234 "Rhine, this is Boffo 2234, PAN PAN PAN" ATC, "Boffo 2234, say again?" BA2234 "Rhine, this is a PAN call from Boffo 2234" (at this point you can almost hear the Boffo skiper thinking "bloody foreigners" ATC, "Boffo 2234, are you declaring an emergency?" BA2234 "Negative Rhine, Boffo 2234 is making a PAN call" ATC, -silence- BA 2234, Rhine, we have a pasenger having a heart attack, we're mkaing a PAN call" ATC, "Boffo 2234, do you wish to declare an emergency?" BA 2234 "Nega- Oh, yes, yes, we're declaring an emergency, we'd like to divert to Frankfurt immediatly. " ATC, roger 2234, fly heading 330 and descend now to FL 150" No ****, this really happened. I think it actually took longer than this. The Brit captain just wouldn't let go.... The PAN actually sounds to me like a good idea, but as I always say I'm still a lowly stude! Being able to differentiate between a Mayday (basically aircraft in imminent danger) and PAN (something that needs priority but nothing that will endanger the aircraft in short order) seems like a good idea to me. Anyway, the formt of his PAN PAN call was all wrong according to CAP 413 I can't remember precisely what he said, but the jist of the conversation is there and it's pretty much the way it happened. I don;'t even know the format off th etop of my head, but he probabyl did it right. That's my current bug-bear actually. The only exam I've got left to do (apart from the Skills test) is the R/T practical. On this, unless you're word perfect on the Mayday call you've failed, but what are the odds of a controller ignoring your mayday because you forgot (for example) your pilot qualifications in the mayday call? Pretty slim. I've never even used the Mayday and I've had several emerencies and just declared an emergency and got everything I needed. I think I'd ony use a Mayday to cut through heavy radio traffic if it was neccesary. Bertie |
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