Simviation Forum - Navigation Before The GPS

Jan 24^th, 2006 at 5:48pm

cheesegrater Ex Member

I was just wondering, how did aircraft navigate across an ocean before the days of the GPS? For example flying across the Atlantic or Pacific. There are no VORs or ADFs on the water.

Back to top

IP Logged

Reply #1 - Jan 24^th, 2006 at 5:52pm

Woodlouse2002 Offline
Colonel
I like jam.
Cornwall, England

Gender:
Posts: 12574

Quote:

I was just wondering, how did aircraft navigate across an ocean before the days of the GPS? For example flying across the Atlantic or Pacific. There are no VORs or ADFs on the water.

Compass courses, Sextant sights and a chronometer. The same way infact that ships used before GPS and radio navigation. Tongue

Woodlouse2002 PITA and BAR!!!!!!!!&&&&Our Sovereign Lord the King chargeth and commandeth all persons, being assembled, immediately to disperse themselves, and peaceably to depart to their habitations, or to their lawful business, upon the pains contained in the Act made in the first year of King George the First for preventing tumults and riotous assemblies. God Save the King.&&&&Viva la revolution!

Back to top

IP Logged

Reply #2 - Jan 24^th, 2006 at 6:48pm

Woodlouse2002 Offline
Colonel
I like jam.
Cornwall, England

Gender:
Posts: 12574

Mustn't forget good old dead reckoning either.

Woodlouse2002 PITA and BAR!!!!!!!!&&&&Our Sovereign Lord the King chargeth and commandeth all persons, being assembled, immediately to disperse themselves, and peaceably to depart to their habitations, or to their lawful business, upon the pains contained in the Act made in the first year of King George the First for preventing tumults and riotous assemblies. God Save the King.&&&&Viva la revolution!

Back to top

IP Logged

Reply #3 - Jan 24^th, 2006 at 7:05pm

Nexus Offline
Colonel
The greater of two evils...

Gender:
Posts: 3282

Quote:

I was just wondering, how did aircraft navigate across an ocean before the days of the GPS? For example flying across the Atlantic or Pacific. There are no VORs or ADFs on the water.

There were several options to choose from.
You had the Loran-C and OMEGA/VLF systems, both which used ground stations with ultra long range. And these were pretty reliable

But the dominant one was, and still is, the Inertial Navigation system. The INS and the derative IRS is installed in pretty much EVERY airliner, from Airbus A330 to the Boeing 747 etc. And it is fully capable of navigating the aircraft for you if you lose GPS.

I suggest you read my answer in this thread about the INS/IRS, if you want to know more about the subject

http://www.simviation.com/cgi-bin/yabb/YaBB.cgi?board=genav;action=display;num=1...

Back to top

IP Logged

Reply #4 - Jan 24^th, 2006 at 9:44pm

beaky Offline
Global Moderator
Uhhhh.... yup!
Newark, NJ USA

Gender:
Posts: 14187

When Lindbergh did it, he made small course changes at set time intervals, using an earth-induction compass (sort of a radio receiver that picks up the Earth's magnetic field) to set his heading, following a carefully-planned Great Circle route across the ocean. It worked out pretty well, even though he could only guess as to how much the wind would really drift him- not too many reliable wind forceasts available those days, and he had no radio to get weather reports with... too heavy.
He used a wet compass (regular old iron-bar compass that always points more or less towards the North or South Pole)to check against the earth-induction compass, but it had to be placed in an area where he needed a miror to see it. The day it was installed, they had no mirror, but a young lady in the crowd gathered outside the hangar at Curiss Field gave them the mirror from her compact, according to Lindbergh's own account. It was just the right size, and not too heavy (LOL).
He could have used a radio to get bearings from ships at sea, but decided the marine-band units available at the time were too heavy.
So other than the fancy-for-its-day induction compass, he did it by sheer deduced reckoning: no landmarks to see, so it was all about careful planning, accurate timekeeping, precision maneuvers, and lots of luck with the wind... Grin

Back to top

IP Logged

Reply #5 - Jan 25^th, 2006 at 4:46am

C Offline
Colonel
Earth

Posts: 13144

What's GPS? Wink

Dirty word, almost as bad as crevice... Grin

Back to top

IP Logged

Reply #6 - Jan 25^th, 2006 at 6:48am

Woodlouse2002 Offline
Colonel
I like jam.
Cornwall, England

Gender:
Posts: 12574

Pity airliners arn't made with Astrodomes any more. They usually complemented the lines quite nicely.

Woodlouse2002 PITA and BAR!!!!!!!!&&&&Our Sovereign Lord the King chargeth and commandeth all persons, being assembled, immediately to disperse themselves, and peaceably to depart to their habitations, or to their lawful business, upon the pains contained in the Act made in the first year of King George the First for preventing tumults and riotous assemblies. God Save the King.&&&&Viva la revolution!

Back to top

IP Logged

Reply #7 - Jan 25^th, 2006 at 9:29am

beaky Offline
Global Moderator
Uhhhh.... yup!
Newark, NJ USA

Gender:
Posts: 14187

Quote:

What's GPS? Wink

Dirty word, almost as bad as crevice... Grin

I think it stands for "Glib Pilot Syndrome"... yeah, that's it.
Grin

Back to top

IP Logged

Reply #8 - Jan 25^th, 2006 at 11:42am

Hester Offline
Colonel
Canada

Gender:
Posts: 15

"Great Pilot Simulator"? Wink

Back to top

IP Logged

Reply #9 - Jan 25^th, 2006 at 10:22pm

cheesegrater Ex Member

Quote:

There were several options to choose from.
You had the Loran-C and OMEGA/VLF systems, both which used ground stations with ultra long range. And these were pretty reliable

But the dominant one was, and still is, the Inertial Navigation system. The INS and the derative IRS is installed in pretty much EVERY airliner, from Airbus A330 to the Boeing 747 etc. And it is fully capable of navigating the aircraft for you if you lose GPS.

I suggest you read my answer in this thread about the INS/IRS, if you want to know more about the subject

http://www.simviation.com/cgi-bin/yabb/YaBB.cgi?board=genav;action=display;num=1...

Curious. The freeware INS gauge looks just like a GPS gauge found in many panels. In a real airliner (for example 747-200 or Tristar) is this a GPS or INS?

Back to top

IP Logged

Reply #10 - Jan 25^th, 2006 at 10:47pm

Nexus Offline
Colonel
The greater of two evils...

Gender:
Posts: 3282

Not really sure what you mean by that. Are you talking about the CIVA INS gauge by simufly?

Although some 747-200's may be GPS retrofitted, but I can assure you that both the 742 and the L1011 TriStar used INS (Probably a Delco Carousel or a Litton unit)

Take a look at this picture of a 747-200 flightdeck. Just above the throttle levers is one of the INS control display units. In newer aircrafts that spot is now occupied by the FMC, and the inertial nav display is usually located on the overhead panel instead

http://www.airliners.net/open.file/586732/L/

Back to top

IP Logged

Reply #11 - Jan 25^th, 2006 at 11:19pm

cheesegrater Ex Member

Quote:

Not really sure what you mean by that. Are you talking about the CIVA INS gauge by simufly?

Although some 747-200's may be GPS retrofitted, but I can assure you that both the 742 and the L1011 TriStar used INS (Probably a Delco Carousel or a Litton unit)

Take a look at this picture of a 747-200 flightdeck. Just above the throttle levers is one of the INS control display units. In newer aircrafts that spot is now occupied by the FMC, and the inertial nav display is usually located on the overhead panel instead

http://www.airliners.net/open.file/586732/L/

Yes, that is the gauge I was thinking of. Thanks for the responses.

Back to top

IP Logged

Reply #12 - Jan 26^th, 2006 at 12:32am

beaky Offline
Global Moderator
Uhhhh.... yup!
Newark, NJ USA

Gender:
Posts: 14187

Quote:

"Great Pilot Simulator"? Wink

Naahhh... a Great Pilot wouldn't need no stinkin' satellites to get a nav fix... Wink

Back to top

IP Logged

Reply #13 - Jan 26^th, 2006 at 12:34am

beaky Offline
Global Moderator
Uhhhh.... yup!
Newark, NJ USA

Gender:
Posts: 14187

Quote:

There were several options to choose from.
You had the Loran-C and OMEGA/VLF systems, both which used ground stations with ultra long range. And these were pretty reliable

But the dominant one was, and still is, the Inertial Navigation system. The INS and the derative IRS is installed in pretty much EVERY airliner, from Airbus A330 to the Boeing 747 etc. And it is fully capable of navigating the aircraft for you if you lose GPS.

I suggest you read my answer in this thread about the INS/IRS, if you want to know more about the subject

http://www.simviation.com/cgi-bin/yabb/YaBB.cgi?board=genav;action=display;num=1...

Obviously I was looking too far back: INS was and is a very useful tool, and predates GPS by many years.
And good ol' Loran: surprisingly accurate.

Back to top

IP Logged

Reply #14 - Jan 26^th, 2006 at 6:58pm

Nexus Offline
Colonel
The greater of two evils...

Gender:
Posts: 3282

Quote:

Obviously I was looking too far back: INS was and is a very useful tool, and predates GPS by many years.
And good ol' Loran: surprisingly accurate.

And here I tought that I made a goof out of myself since the responses was dominated by celestial navigation and dead reckoning etc. I started to think "hmm...maybe I'm waaay out of the ballpark on this one" Grin

Back to top

IP Logged

	Search the archive: