7 ms·
FYI: nm = nautical miles, not nanometers.
by jp57 2y ago
FYI: nm = nautical miles, not nanometers.
- barbazoo 2y agoGiven the context, I'd say NM actually https://en.wikipedia.org/wiki/Nautical_mile https://en.wikipedia.org/wiki/Nautical_mile
- jp57 2y agoI was clarifying the post title, which uses "nm".
- pvitz 2y agoYes, it looks like they should have written "NM" instead of "nm".
- andkenneth 2y agoNo one is using nanometers in aviation navigation. Quite a few aviation systems are case insensitive or all caps only so you can't always make a distinction. In fact, if you say "miles", you mean nautical miles. You have to use "sm" to mean statute miles if you're using that unit, which is often used for measuring visibility.
- ianferrel 2y agoSure but I could imagine some kind of software failure caused by trying to divide by a distance that rounded two zero because the same location was listed in two databases that were almost but not exactly the same location. In fact I did when I first read the headline, then realized that it was probably nautical miles. That would be roughly consistent with the title and not a totally absurd thing to happen in the world.
- scarlehoff 2y agoThis is exactly what I thought q when I first read the title.
- anigbrowl 2y agoIndeed, but you can easily imagine a software glitch over what looks like a single location but which the computer sees as two separate ones.
- jp57 2y agoIndeed, having locations internally represented in software with a resolution of nanometers is as ridiculous as having your calendar's internal times represented as milliseconds since some arbitrary moment more than fifty years ago!
- deleted 2y ago[deleted]
- rob74 2y agoYes. And, to quote the Wikipedia article: "Symbol: M, NM, or nmi". Not nm (as used in the title, but the article also uses it).
- snakeyjake 2y ago[flagged]
- remram 2y agoI assumed it probably wasn't nanometers but I have no idea what a nautical mile is. Turns out 3600 NM = 6666 km
- contravariant 2y agoWell, I certainly read nanometers, but I have to admit I may not be mentally well.
- ortusdux 2y agoWell TIL I must be illiterate or mentally unwell.
- jp57 2y agoSorry no. One interpretation, especially on this site, is that the problem was some kind of database bug, maybe where the same location was entered twice and a tiny location error ended up creating two locations. I expect that out of any random sample 500 million literate and mentally healthy English speakers, more than 450 million of them are totally unaccustomed to thinking about nautical miles ever. Even people in science, or even who might have dealt with nanometers in school do not typically think about nautical miles unless they are sailors or airplane pilots.
- snakeyjake 2y ago[flagged]
- s_tec 2y agoI assumed the post title meant nanometers. Why? Floating-point rounding bugs. A nanometer is about 9e-15 degrees of latitude, which is right about where a double-precision floating point number runs out of digits. So, if a piece of software uses exact `==` equality, it could easily have a bug where two positions 3600 nanometers apart are seen as being different, even though they should be treated as the same.
- dietr1ch 2y agoThanks, from the title I was confused on why there was such a high resolution on positions.
- deleted 2y ago[deleted]
- ikiris 2y agoNanometers would be a very short flight.
- cheschire 2y agoI could imagine conflict arising when switching between single and double precision causing inequality like this.
- noqc 2y agoman, this ruins everything.
- andyjohnson0 2y agoEven though I knew this was about aviation, I still read nm as nanometres. Now I'm wondering what this says about how my brain works.
- lostlogin 2y agoIt says ‘metric’. Good.
- tialaramex 2y agoIndeed. There are plenty of things in aviation where they care so much about compatibility that something survives decades after it should reasonably be obsolete and replaced. Inches of mercury, magnetic bearings (the magnetic poles move! but they put up with that) and gallons of fuel, all just accepted. Got a safety-of-life emergency on an ocean liner, oil tanker or whatever? Everywhere in the entire world mandates GMDSS which includes Digital Selective Calling, the boring but complicated problems with radio communication are solved by a machine, you just need to know who you want to talk to (for Mayday calls it's everyone) and what you want to tell them (where you are, that you need urgent assistance and maybe the nature of the emergency) On an big plane? Well good luck, they only have analogue radio and it's your problem to cope with the extensive troubles as a result. I'm actually impressed that COSPAS/SARSAT wasn't obliged to keep the analogue plane transmitters working, despite obsoleting (and no longer providing rescue for) analogue boat or personal transmitters. But on that, at least, they were able to say no, if you don't want to spend a few grand on the upgrade for your million dollar plane we don't plan to spend billions of dollars to maintain the satellites just so you can keep your worse system limping along.
- mnw21cam 2y agoAir pressure is reported in hectopascals and fuel quantity in kilograms (or tons). It's only in America where this isn't the case. We're still using feet for altitude in most places though (it's mainly Russia that uses metres).
- 2y ago
- QuercusMax 2y agoAh! I thought this was a case where the locations were just BARELY different from each other, not that they're very far apart.
- fabrixxm 2y agoIt took me a while, tbh..
- cduzz 2y agoI was wondering; it seemed like if the to airports were 36000 angstroms apart (3600 nanometers), it'd be reasonable to give them the same airport code since they'd be pretty much on top of each other. I've also seen "DANGER!! 12000000 μVolts!!!" on tiny little model railroad signs.
- atonse 2y agoThat's so adorable (for model railroads)
- joemi 2y agoIt's quite amusing that they used the incorrect, lowercase abbreviation for "nautical mile" which means something else ("nanometer") in an article about a major issue caused by two things sharing the same abbreviation.
- SergeAx 2y agoI learned navigation around 2005, and we used "nm" then. I honestly don't remember the moment when this abbreviation was granted to nanometer.
- ainiriand 2y agoExactly the first thing that came to my mind when I saw that abbreviation.
- hughdbrown 2y agoWow, I read this article because I could not understand how two labeled points on an air path could be 3600 nanometers apart. Never occurred to me that someone would use 'nm' to mean nautical miles.
- animal531 2y agoAnd for those like myself wondering how much 3600nm is, it is of course 0.0036mm
- larsnystrom 2y agoAh, yes, like when people put in extraordinary amounts of effort to avoid sending a millibit (mb) of data over the wire.
- endoblast 2y agoWe all need to stop using abbreviations, in my opinion. EDIT: I mean the point of abbreviations is to facilitate communication. However with the world wide web connecting multiple countries, languages and fields of endeavour there are simply too many (for example) three letter acronyms in use. There are too many sources of ambiguity and confusion. Better to embrace long-form writing.