For much of human history, people needed specialized training to navigate from point A to point B, like learning to follow the stars or use a sextant and chronometer. Today, thanks to global positioning satellites that send signals to our phones, we can all be successful navigators. Kojo talks with two curators about the history and future of navigation and a new exhibit at the Smithsonian’s Air and Space Museum called “Time and Navigation: The Untold Story of Getting from Here to There.”


  • Andrew Johnston Geographer, National Air and Space Museum; Co-Curator of "Time and Navigation: The Untold Story of Getting From Here to There"
  • Roger Connor National Air and Space Museum Curator of Vertical Flight; Co-Curator of "Time and Navigation: The Untold Story of Getting From Here to There"

Photos From The Smithsonian’s ‘Time And Navigation’ Exhibit

How GPS Works

This animation showcases the various components of the Global Positioning System and how they work together to help determine position.


  • 12:33:01

    MR. KOJO NNAMDIIn the days when exploration was a nautical adventure, navigators followed the stars across the ocean. Even the early aviators use celestial navigation to plot their course before transmission towers sprouted around the globe and sent radio signals to guide pilots across the sky. Now, signals from satellites guide us with such precision that Google Maps offers directions by car, bus, bike or foot. The result is the demise of the highly skilled navigator. A craft that once required serious training is now relegated to a computer chip.

  • 12:33:34

    MR. KOJO NNAMDIA new permanent exhibit at the National Air and Space Museum explores the history and the future of navigation, and shows why time is the key variable that allows us to find our way without getting lost. Joining us in studio is Roger Connor, curator of aviation of the National Air and Space Museum. He is co-curator of the new Time and Navigation exhibit. Roger Connor, thank you for joining us.

  • 12:33:59

    MR. ROGER CONNORThank you for having me, Kojo.

  • 12:34:00

    NNAMDIJoining us in studio also is Roger's co-curator, Andrew Johnston. He is geographer at the National Air and Space Museum. Andrew Johnston, thank you for joining us.

  • 12:34:10

    MR. ANDREW JOHNSTONThanks for having us today.

  • 12:34:11

    NNAMDIYou too can join this conservation. Give us a call, 800-433-8850. How good a navigator are you? Can you find your way around without a GPS? Well, our two guests came over here by Metro. Maybe it would have been better had they navigated themselves because you got stuck for a little while on the train, didn't you?

  • 12:34:28

    CONNORYeah, it wasn't so much a navigation problem as it was a train malfunction.

  • 12:34:32

    NNAMDIExactly right. Explain how the earliest navigators used the stars, Andrew, to figure out where they were and develop instruments like the sextant and the chronometer to help?

  • 12:34:41

    JOHNSTONAll right. In Time and Navigation, we're telling one of the great unknown stories -- untold stories of getting from here to there. It turns out in order to know where we are anywhere on the planet, you actually need to know the time. And that's true today with GPS, which works only because there are precise atomic clocks on board all those satellites.

  • 12:35:00

    JOHNSTONI mean, if you were to go back in time, centuries, the way navigators on ships found their way around was by using instruments like chronometers and sextants to determine their latitude and longitude.

  • 12:35:11

    NNAMDIRoger, how did the invention of airplanes change the requirements for navigation?

  • 12:35:16

    CONNORThe problem with airplanes was that you now have to do what those navigators at sea did, and it took those guys about 15, 30 minutes or so to work out a position looking at the stars. If you wanted to do this in an airplane, of course, you're traveling over 100 miles an hour, so you have a problem right there, but also you're doing this in a cramped cockpit.

  • 12:35:34

    CONNORIt's hard to see the horizon. So trying to get the solutions down for the star sightings down to under a minute was a real challenge that was driving a lot of the innovations in navigation in the late 1920s or late 1930s.

  • 12:35:47

    NNAMDIHere's what I find fascinating: Why did Charles Lindbergh decide to learn navigation not before but after his historic flight to Paris?

  • 12:35:55

    CONNORRight. So the navigational equipment that was available to aviators in the 1920s was really pretty poor. Again, it was equipment that was designed for the mariner and really not up to the task for the aviator. And so Lindbergh, when he flew to Paris, really just kinda gambled, pointing his plane in the right direction. He knew he was gonna get to Europe one way or the other as long as he took enough gas. So it wasn't really a problem for that flight.

  • 12:36:20

    CONNORBut when he's taking the Spirit of St. Louis on a victory lap around Latin America and the Caribbean in early 1928, he gets lost on at least two occasions. One time, he's over the Straits of Florida trying to make it back to the U.S. and winds up 300 miles off course because his compass wasn't playing nice. So he, at that point, realizes that if aviation is really gonna become a mainstay of commercial travel that something has to be done.

  • 12:36:49

    CONNORAnd so at that point, he manages to hook up with a naval officer in Annapolis, P.V.H. Weems, and together, they helped each other work out a system of reliable celestial air navigation.

  • 12:37:03

    NNAMDIWe're talking about the exhibit at the Smithsonian on navigation, inviting your calls at 800-433-8850. Do you think you could navigate by the stars? Give us a call, 800-433-8850. Send email to, or send us a tweet, @kojoshow. Andrew, why is this exhibit called Time and Navigation? How does knowing the precise time make precise navigation possible?

  • 12:37:28

    JOHNSTONIt's because whenever you're trying to determine where you're located, you're always trying to figure out whether you're located relative to another spot. So what we would do at sea if you were, 200 years ago, on a seagoing vessel, you could use time to track the movements of the stars and the sun and the moon in the sky, basically using the Earth as a clock because the Earth rotates about once every 24 hours.

  • 12:37:51

    JOHNSTONAnd so if you could compare the location of an object, a celestial object and your location on the ship and compare it to where you think it would be in the sky whereas another city is on this side of the ocean, you could figure out how far away you are, in latitude and longitude, relative to that city. And then today, with systems like GPS, what we're doing is we're not measuring seconds of time, we're measuring billionths of the second.

  • 12:38:15

    JOHNSTONAnd what the system like GPS does is it actually measures the amount of time it takes for signals to move at the speed of light from an orbiting satellite to your ground location. And some satellite signals arrive just, you know, a few thousandths of a second before others. And so you can measure that time offset and you can determine where you are based on the known position of the satellites.

  • 12:38:34

    NNAMDIAndrew Johnston is a geographer at the National Air and Space Museum and co-curator of the new Time and Navigation exhibit. Roger Connor is his co-curator. He is curator of aviation at the National Air and Space Museum, co-curator of this specific exhibit. Roger, where does the saying synchronize your watches come from?

  • 12:38:53

    CONNORSo Charles Lindbergh's tutor in navigation, P.V.H. Weems, invented the hack watch. So this is the aviator's watch, and they came out in about 1928. And the idea was that the Navy and other services would broadcast time signals that aviators could synchronize their watches to exactly so they could get an accurate reading when they were taking these star sightings.

  • 12:39:16

    CONNORSo if you're -- if you don't have an accurate -- if you're not able to set your watch to the second, what happens is if you're at the equator, your watch could be up to 30 seconds off. That's a seven-mile error. So very small differences in time on a watch had real differences in navigational accuracy.

  • 12:39:32

    NNAMDIWhat are the different methods aviators have used to navigate, and what system do commercial airline pilots use today?

  • 12:39:40

    CONNORToday, GPS is starting to become dominant. For air traffic control and navigation, the core system is still largely a system that came out in 1920s for the airmail pilots. And we used as system of airways. So these are set highways in the sky that are kinda marked out based upon ground-based beacons. GPS allows you to undo these things theoretically. You can fly straight from point A to point B.

  • 12:40:06

    CONNORBut the reality is we're still not quite at that point yet just because the system is so coded into this older, maybe even obsolete technology. But in the next decade or so, we're looking at a -- at an entirely new system. The FAA calls this NextGen, and the idea is that you undo all those old highways in the sky so that you have this option of going straight from A to B. And this has huge impacts in terms of environmental impacts, fuel consumption, efficiency, time savings and so forth, as well as safety.

  • 12:40:37

    NNAMDIOn to the telephones. Here is Tom in Takoma Park, Md. Tom, you're on the air. Go ahead, please.

  • 12:40:43

    TOMKojo, I can't wait to see this exhibit at the Smithsonian. I'm a former Navy navigator, naval flight officer, and I'm wondering -- you know, we were taught, you know, dead reckoning navigation. In other words, if you're talking about the importance of time, you could take -- whether you -- whether we were using LORAN, long distance radio aid to navigation...

  • 12:41:08

    NNAMDIYou should see both of our panelists nodding their heads in agreement. They know exactly what you're talking about. Go ahead, please, Tom.

  • 12:41:12

    TOMOr we had periscopic sextants that would poke out the skin of the -- on the top of the airplane and take sights on stars, which actually was far more accurate than LORAN. But it would only tell you where you were at that time, at that moment in time. So you had to plot your course and speed from there. But once you've got a couple of these fixes, as we liked to call it, navigational fix or spot, you could connect the dots and, you know, you'd be very accurate, and you could fly across the ocean and find a tiny, little island successfully.

  • 12:41:48

    NNAMDII'm so glad you brought that up, Tom, because while both of our panelists would like to comment on that, I got a question to throw in too. But go ahead, Andrew. What were you gonna say?

  • 12:41:56

    JOHNSTONWell, I'm just so glad to hear what he had to say because it's exactly some of the themes that we pick up in the exhibition, that in order to navigate successfully, it requires a -- multiple different kinds of information. And using celestial techniques, like using a sextant on an airplane, is great, but what do you do if it's cloudy? That's why radio aids were introduced, like LORAN, and we cover those two stories in the exhibition. It's a story of continual improvements and advances to try to meet new challenges in different time periods.

  • 12:42:27

    NNAMDIMy question, Roger, has to do with one of the themes of the exhibit, being the fact that navigation has gone from something done by Tom, a highly skilled individual, to something that's done by a microchip. Explain that transformation, please.

  • 12:42:42

    CONNORWell, I think you need to look at -- World War II is real key moment on this. So 1930s, as we talked about, you have a Charles Lindbergh type, you know, this somebody that's looking to undergo a long course of training and requires very specialized tools to accomplish their task. But World War II, you have a need for tens, even over 100,000 navigators for aircraft and ships, and these are 18-, 19-year-olds.

  • 12:43:09

    CONNORYou're gonna give them six or eight weeks of training, and then turn them loose and expect them to do what a Charles Lindbergh had done only with, you know, a significant amount of experience just, you know, a few years earlier. And so very quickly having systems that were automating the process became paramount. And, really, that -- you know, World War II, Cold War is really pushing the ability to have fairly sophisticated, expensive systems that were able to navigate submarines or ships or aircraft to anywhere in the world.

  • 12:43:44

    NNAMDITom, thank you very much for your call.

  • 12:43:45

    TOMI wonder if there's a danger in getting, you know, too clever here or -- GPS is terrific, you know, but what if you're hacked or -- I hope they're still teaching some backup navigational skills.

  • 12:43:55


  • 12:43:56

    JOHNSTONYeah. In fact, one of the themes that we briefly touch on in the exhibition is that we have these systems that allow almost anybody with the right kind of device in the palm of their hand to be a global navigator, you know, for better or worse, right? And so there are people that do ask, what is the backup to these sorts of systems?

  • 12:44:16

    JOHNSTONAnd because it's a story that's evolving quickly, we can't go into brutal detail in a museum exhibition, but we do at least highlight some of those current questions 'cause we want our visitors to understand that the story is not over, that GPS is a system that works great, but there are, right now, thousands of clever engineers out there trying to develop new solutions to meet the challenges of modern society.

  • 12:44:39

    CONNORThe navigation community is actually very keen on the notion that we get back to the old model of having multiple methods of -- that are overlaid together. And so even if you're looking at something like a cellphone, you're using cell triangulation as well as the GPS chip, but we're also, in a lot of military systems, we're overlaying inertial navigation systems on top of that. And so even though your cellphone may appear to be using GPS when you're inside a building, it's actually using something else.

  • 12:45:10

    CONNORAnd so that's the real advance that's under -- that we're looking at right now, that all these things are beginning to be integrated so that your little pocket device is navigating seamlessly regardless whether you're inside or outside.

  • 12:45:23

    NNAMDIAndrew, you mentioned this earlier, but explain why the accuracy of a GPS depends on an atomic clock that's precise down to a billionth of a second.

  • 12:45:31

    JOHNSTONRight. So these systems work because we're receiving signals from orbiting satellites. And the way that a position is determined with GPS is that we know the location of these satellites through time because they're -- the orbits are tracked, and that information is transmitted down to the ground device. So in order to determine where we are, the system was designed in such a way so that it can measure the arrival time of these different signals.

  • 12:46:00

    JOHNSTONNow, it turns out, of course, these signals move at the speed of light. That's pretty fast. And so depending on where a satellite is in the sky, the arrival time of different signals will be within a second, but they'll just be a split second apart. In other words, the signal from one satellite might arrive just a split second, a few thousandths of a second earlier than the satellite that might be orbiting overhead on -- over there in a different part of the sky.

  • 12:46:23

    JOHNSTONSo the device needs to -- every GPS device needs to measure the time difference in the arrival time of these signals that are moving at the speed of light. And people often have a hard time imagining what the speed of light is, but it is a speed that can be measured. And if we can measure the arrival time of the signals down to a few billionths of a second, you can determine your position down to about the distance that light speed will travel in a few billionths of a second, you know, which is down on the order of tens of meters.

  • 12:46:54

    NNAMDIGot to take a short break. Tom, once again, thank you very much for your call. If you'd like to join the conversation, give us a call at 800-433-8850. What's your favorite navigation tool? You can also send us email to I'm Kojo Nnamdi.

  • 12:48:49

    NNAMDIWelcome back. We're talking with Roger Connor. He is curator of aviation at the National Air and Space Museum. He is co-curator with Andrew Johnston of the new "Time and Navigation" exhibit. Andrew Johnston is geographer at the National Air and Space Museum. We've been taking your calls at 800-433-8850. We're still taking your calls at that number, so give us a call. You can send email to Roger, what are some instances of navigation gone wrong?

  • 12:49:20

    CONNORThis is -- one of the more interesting parts of the exhibit we've got to put together was trying to pinpoint those moments at which an episode of disaster leads to change. So one of the things that we've picked out is the British fleet running aground in the early 18th century, which helps lead to the prize that launches the maritime chronometers that make these economic empires of the 19th century so possible. We talked about Amelia Earhart and why she disappeared. KAL 007 is another one that we talked about.

  • 12:49:54

    NNAMDIThe Korean airlines that was shot down by the Soviets in the 1980s.

  • 12:49:59


  • 12:49:59


  • 12:50:00

    NNAMDIWhat's the future of navigation, Andrew? What comes next?

  • 12:50:04

    JOHNSTONRight. What we're seeing right now are more and more devices being integrated both hardware and software. What I mean by that is that, you know, up until maybe 15 years ago, there are devices that could use GPS signals to determine position. And it would read out latitude and longitude, which for people like me are -- is useful information. But for most people, those are just numbers that don't really mean anything.

  • 12:50:28

    JOHNSTONIt's only with the integration with the digital map data that these kinds of navigation tools become useful. And so that's how people are used to navigating now with their mobile devices, in their phones because they're able to call up a map. These -- one of the things we have on display in the exhibition is -- that provides a nice contrast, I suppose, is we have a submarine navigation equipment. We have -- it's probably a couple thousand pounds of equipment that was used on board the USS Alabama.

  • 12:50:55

    JOHNSTONAnd it was a inertial navigation system that also receives signals from a system called Transit to determine position onboard a submarine and the gyroscopes and accelerometers and radio receivers. Well, also at the other end of the hall, we have a mobile phone on display, a normal off-the-shelf mobile phone that we've disassembled to show the interior components to show where the GPS and the accelerometers and the gyroscope are inside this device. But it doesn't weigh a couple thousand pounds.

  • 12:51:19

    JOHNSTONIt sits on the palm of somebody's hand, and they can call up these maps almost anywhere they are. In the coming years, what we're going to see are even more features integrated into these devices. There is gonna be chip-scale atomic clocks, so you're gonna have precise time under billions of a second inside these devices, which allows you -- it gives you a back up to satellite signals. And it's gonna be impacting people's everyday lives in the way we get around.

  • 12:51:41

    JOHNSTONWe touched on a story of the arrival of autonomous vehicles, robotic cars may be on our highways in the coming decades and what are some of the questions that arise from those issues.

  • 12:51:53

    NNAMDIOn to Bill in Baltimore, Md. Bill, your turn.

  • 12:51:57

    BILLHi, Kojo. Yeah. This is really interesting format, and I'm -- I can't wait to see the exhibit at the Smithsonian. But I guess my question is, are people have -- is it a learned skill, or do people have a better sense of direction than others? And I'm trying to keep it as politically correct as possible, but...

  • 12:52:20

    JOHNSTONI think we know where are you going. Yeah.

  • 12:52:22

    NNAMDII am not good. I do not have a good sense of direction, Bill, so you don't have to be politically correct. I ask a lot. But if...

  • 12:52:29


  • 12:52:30

    NNAMDIDoes that play into...

  • 12:52:30

    BILLYeah. I grew up reading maps. And, you know, I was in the Army and learned how to use a compass. And, you know, I still like to look at maps and things like that. And I think our society has really become over dependent on these GPS devices. And really, people don't know where they are. And, you know, I find that kind of, you know, not within control of the environment I like to be. I always like to know a sense of where I am. So I don't know if that's, you know, overly confident.

  • 12:52:58


  • 12:52:59


  • 12:52:59 is Andrew.

  • 12:53:00

    JOHNSTONIn fact, Bill, we actually asked that question on one of the panels in the exhibition. We asked our museum visitors, what do you think, visitors, are we losing skills while we have access to this advance technology? And we're hoping to maybe have visitors ask questions like, well, when was the last time you used a paper map? And how about a wrist watch?

  • 12:53:23

    JOHNSTONAnd we suspect that people like Bill will probably say, yes, I miss paper maps. Me, I use paper maps all the time. But younger visitors will probably say things like, what's a paper map?

  • 12:53:33


  • 12:53:33

    JOHNSTONHow do I fold this thing?

  • 12:53:35

    NNAMDIBill, thank you very much for your call. Roger, what does the future of navigation look like for commercial airplanes? Will air traffic controllers become obsolete?

  • 12:53:45

    CONNORIt's fascinating to lead in what Andrew just said. I have an app I can pull up on my iPad where I can see airliners on the other side of the world -- Australia, China, whatever -- I can see their call sign, their altitude, their destination, heading airspeed, all that information pretty much real time. It's unbelievable. Just, you know, readily available app, that's all I need. And that's what we're looking at now is this integration of data at the point where no longer our air traffic control centers essentially isolated.

  • 12:54:21

    CONNORIt's just that rate -- what that radar sees or that pilot is seeing in terms of their radio navigation equipment. It's all integrated now where it can be centralized, it can be automated to a degree that it wasn't before. And this is going to have some very significant implications that we're gonna have to deal with. Some of these things are very positive. We can improve efficiency. We can reduce infrastructure. These are all great things. But it also is going to create some, I think, cultural problems.

  • 12:54:49

    CONNORYou know, one of the things that, of course, we're dealing with now is the implementation of unmanned systems. For aviation, it's really kind of the cutting edge of this at the moment. There are a lot of commercial operators, a lot of government entities that wanna operate UAVs in the National Airspace System. And you got to have these things play nice with commercial aircraft, obviously for safety reasons, and how do you do that? So this is a big challenge that we're gonna have to deal with.

  • 12:55:15

    CONNORAnd, you know, this is also true for surface transportation as well. The money isn't there for the big infrastructure projects anymore, so you have to deal with the optimization of road networks. So being able to know and track vehicles, to know where they are, to synchronize traffic signals, all that sort of thing, you know, part of this is about the collection and sharing of data which is something that society has a lot of concerns about.

  • 12:55:44

    NNAMDIWhen you say UAVs, people think of -- they don't know -- but its drones that we're talking about.

  • 12:55:48


  • 12:55:48


  • 12:55:49

    NNAMDIHere is Dave in Silver Spring, Md. Dave, you're on the air. Go ahead, please.

  • 12:55:53

    DAVE DOYLEThank you, Kojo. Andrew, this is Dave Doyle.

  • 12:55:56

    JOHNSTONDave Doyle, how are you doing?

  • 12:55:57

    DOYLEGood to hear from you, buddy.

  • 12:55:58

    JOHNSTONYeah. Great to hear your voice.

  • 12:55:59

    DOYLEGreat, great show, a great show.

  • 12:56:02


  • 12:56:02

    DOYLEI called and I wanted to ask you if you'd -- I have a question and a comment. I'd like you to describe, at least a little bit, about the evolving nature of the multiple satellite systems, GNSS of the Russians, and Galileo, et cetera. But I was also really glad to hear you talked about the future of positioning technology, what's gonna be happening in the not too distant future in terms of everybody's capacity. One of the things that NOAA's National Geodetic Survey is doing in preparation...

  • 12:56:37

    NNAMDIWe only got about a minute left, Dave, so you got to hurry up.

  • 12:56:39

    DOYLENational -- with the entire coordinate system, in reference to United States, will be changing to meet this demand with the target of 2022.

  • 12:56:49


  • 12:56:49

    NNAMDIOK. Multi-satellite systems.

  • 12:56:50

    JOHNSTONYeah. So Dave is right that there are actually -- GPS is one of several satellite navigation systems up there. Now, it is the largest one and the one that's been around longest and the one that works the best. But we do actually briefly talk about in the exhibition why other countries are launching these satellite navigation systems. And it is because, just like centuries ago, different nations see it as an element of national sovereignty. They wanna have their own capability in space.

  • 12:57:17

    JOHNSTONSo people like Dave -- my recently retired colleague from National Geodetic Survey -- I invite him to visit the museum at the Air and Space Museum. But also if you can't get there, visit the website, And we have section there where you can tell your story, where you were lost and found and your navigation story.

  • 12:57:36

    NNAMDIAnd we have a lot of people who'd like to join this discussion, and we're out of time, so the only thing we can recommend is that you actually go to the exhibit yourself. Dave, thank you very much for your call. Roger Connor is curator of aviation at the National Air and Space Museum and co-curator of the new "Time and Navigation" exhibit. Roger, thank you for joining us.

  • 12:57:54

    CONNORThank you very much.

  • 12:57:55

    NNAMDIAndrew Johnston is his co-curator and geographer at the National Air and Space Museum. Andrew, thank you for joining us.

  • 12:58:02

    JOHNSTONThanks for having us today.

  • 12:58:03

    NNAMDIAnd thank you all for listening. I'm Kojo Nnamdi.

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