pre-VOR navigation....how the heck.....

[matt_gold 1]

So, flying around in the Stearman in heavy winds, feeling very much like I am kite-flying myself, a bit dismayed after failing a clandestine mission and presumably going to jail for illegal trafficking as I'm sure my character deserves for accepting such a dodgy cargo (and probably will again) I got to thinking....

 

How did the pilots navigate before VOR stations? How on earth would they have crossed the oceans and known where they were going without receiving VOR signals and cross-referencing maps?

Actually, how do they do it now?!?! VOR is line of site, the world is round, and the oceans are....well they are oceans, and not littered with VOR buoys....or are they?

 

I know, I know, basic stuff. As usual, much gratitude for the free flow of information from the pros.

[Heimi 91]

Before VOR`s there were NDB`s (since WW1).

But in early times the flew only VFR using, landmarks, railroads and roads.

For long distances over ocean they used the same then boatmen: compass, sun and stars.

 

Today there are many systems onboard an aircraft.

IRS, GPS, VOR, DME, NDB and Databases in their FMC with predefined waypoints.

[Dogstar23 0]

They flew on a wing and a prayer.

[RoboRay 126]

Dead reckoning navigation was a big part of it. If you know where you start from, know how fast you are going, and what direction you are going, a map and a clock can give you a fairly good idea of where you probably are, especially if there's anything on the surface to compare to what you see on the map. In a way, dead reckoning is still used by aircraft that carry inertial navigation systems; they've just automated the process.

 

For long over-water flights, celestial observations with a sextant wasn't really totally killed off until GPS became dominant. The sextant kits finally got pulled out of large US Navy aircraft just a few years ago. Nobody really remembered how to use them, anyway.

 

The old VLF Omega system gave you a pretty good idea where you were, too. With only 9 stations covering the entire world, you could fix your position pretty much anywhere. The abandoned Kaneohe Omega station up near the entrance into the H-3 tunnels was another thing I had hoped to see in Flight, but it's not there either.

[jcomm 5,919]

Celestial mainly, such as in ... that the Angels be with me....

[Great Ozzie 101]

Two fundamental skills you learn in Private Pilot training are Pilotage and Dead Reckoning.

 

Pilotage is as Heimi described... referencing to landmarks, rivers, roads, railroads, lakes... anything prominent and easily distinguishable from the air.

 

Dead Reckoning is the ol' "give me a map and a compass and I'm there" (and as the Ray said... knowing groundspeed to estimate checkpoints):

• you plot a bearing (course) on a Sectional Chart, which gives you a "True Heading"
  
• Apply the local Magnetic Variation (taken from the dashed magenta lines on the Sectional). Maui e.g. has almost a 10°E Magnetic Variation, so you subtract 10° from your (true north) course (east is least, west is best... i.e. subtract east, add west)
  
• Apply the aircraft's Magnetic Deviation taken from the compass card. Could range from 0° to 2°or 3°.
  
• Compensate for crosswind. (E6B)
  

One "race" I was involved in at Sim Outhouse... we could only use NDB (mainly). Fine and dandy, but when navigating over the South Pacific from Australia to Chile... there are literally hundreds of miles (over the ocean) with no Nav beacons. Dead Reckoning works excellent. Was a blast to see the ADF needle "come alive" (indicating an island / runway) after hours over the water.

 

One skill I was never taught (it's on the bucket list) is Celestial Navigation. I think the U.S. Navy taught their pilots this until sometime in the '90s. This is the way Charles Lindbergh would have navigated across the Atlantic... using a sextant for a position fix and using dead reckoning to determine course.

 

The sextant kits finally got pulled out of large US Navy aircraft just a few years ago.

 

Wow Ray... would be the bees knees to pick up one of those kits...

[RoboRay 126]

Wow Ray... would be the bees knees to pick up one of those kits...

 

I'm sure they either went for scrap, or the cases are stacked to the ceiling in some warehouse "just in case we ever need them again."

 

I don't think you'd want one, either. They aren't standard sextants like you normally see... there was a periscope-style receptacle in the top of the fuselage that you mounted the sextant into when using it. I'm not sure they would even be useable without being mounted. I never even took one out of the case, myself.

 

I can find the North Star and (on a good night) the Southern Cross (depending on what side of the planet I'm on), and that's about it.

[EastCoastGuy 0]

Reminds me of a dialog from the movie Hanover Street that went something like:

 

Crew1: Isn't it funny how sometimes it looks like the propellers are running backwards?

Crew2: Backwards?? How can you be sure they're not running backwards?

Crew1: Well, if we take off facing Germany, and we end up in Ireland, then they were running backwards.

[RoboRay 126]

Either way, you can end up with some fine beer.

[vololiberista 205]

The sextant here: http://library.avsim...=root&Go=Search

 

is also installed on the VC10 model.

The greatest story of dead reckoning is Ernest Shackleton crossing 800 miles of the Southern Ocean in seas so rough they were only able to take 4 sightings of the sun!!

 

vololiberista

[vololiberista 205]

The sextant here: http://library.avsim...=root&Go=Search

 

is also installed on the VC10 model.

The greatest story of dead reckoning is Ernest Shackleton crossing 800 miles of the Southern Ocean in seas so rough they were only able to take 4 sightings of the sun!!

 

vololiberista

[ldsandon 0]

Actually, how do they do it now?!?! VOR is line of site, the world is round, and the oceans are....well they are oceans, and not littered with VOR buoys....or are they?

 

Oceanic navigation is now made using inertial systems or GPS, under specific procedures, because there are no VORs nor radar coverage (that's why finding the Air France A330 in the Atlantic Ocean was so difficult). Until a few years ago sextans or similar instruments were used to check and correct the route. Moreover on this very long routes you can't follow a "straight line" using a constant heading because on a sphere the shortest path is a different kind of "line" and heading may chnage along the route.

[RoboRay 126]

Moreover on this very long routes you can't follow a "straight line" using a constant heading because on a sphere the shortest path is a different kind of "line" and heading may chnage along the route.

 

See: http://en.wikipedia.org/wiki/Great_circle

[ldsandon 0]

See: http://en.wikipedia....ki/Great_circle

Yes. See also

http://en.wikipedia.org/wiki/Rhumb_line

http://en.wikipedia.org/wiki/Geodesic

http://en.wikipedia.org/wiki/Flight_planning

 

Navigation over long distances must take into account that the Earth is spheric and also main winds directions. It was (is) true for ships, and is true for airplanes.

[n4gix 4,947]

Don't forget the LORAN (LOng RAnge Navigation) system that was very much depended on for pre-GPS long range navigation by both ocean going vessels and aircraft!

 

http://en.wikipedia.org/wiki/LORAN