What will Happen to you when GPS goes Down

[boatman61]

Well... going West to East across the Atlantic its a piece off cake..
Sail East till a plane goes over at exactly 1725.. turn left and follow its contrail coz that's the Air France St Martin to Paris.. your on course for the UK..
It Works...

[JPA Cate]

Boatie,

I'm wondering if the planes will fly with the GPS system down?

A.

[Auspicious]

Originally Posted by transmitterdan

It is not "easy". This threat is mainly from nation states and is shouldn't be a concern for cruisers not sailing in disputed areas.

Actually we see testing on Chesapeake Bay periodically. Outages are published in LNTM.

[sailorchic34]

Boy, am I late to this game. So assuming that GPS is down and my HP51G calculator with CN programs dumped too along with all my clocks and other electronics, I would get or make a protractor and stick and navigate via latitude as O' Chris Colombo did back in 1492, or I'd stop and ask for directions as Cap'n Ron would do.

Easy Peasy.

[Snowpetrel]

Originally Posted by barnakiel

Now imagine you enter one WPT1 at your EP.

Now imagine you enter the other WPT2 at alt+GHA.

Now what are your dist and dir if you look up such a rte on your now ex-gps plotter?

Any plainest GPS handheld will do the same.

Simple and elegant...(SNIP).

Nice Idea, thanks B. Just need to check if mine can select great circle, not just rhumb line. I normally use the concise system in the back of the almanac. Quick and easy even without a calc, sure beats Nories.

This plotter trick should work for azimuths as well. And to make a simple sun/star compass.

Anybody tried a Bris sextant? Seems like its ideal as a backup.

Edit.. Little rusty on the theory, but wouldnt you enter GHA and Dec for the body at waypoint 2?

[boatman61]

Originally Posted by Ann T. Cate

Boatie,

I'm wondering if the planes will fly with the GPS system down?

A.

Ahahahahaaaa....
Ann.. reckon there's one or two pilots out there who like us remember life without the new technology..

[Ex-Calif]

@Ann - Aircraft navigation is extremely more complex than boats and ships. Commercial aircraft navigation started with DR and CN - like boats but soon directional radio made electronic navigation possible. The purpose of aerial navigation is twofold - find where you are going in all kinds of weather and separate airplanes going to the same place in a 3D airspace.

You understand, of course, there is only one shortest route from New York to Europe and they all wanna use it - both ways!

Long range over water evolved into long rage radio (LORAN) and assigning altitudes and departure times. There were still periods over water where DR was used. When in range of radio again course errors were corrected with radio nav.

In the 1970s Inertial Navigation was created. The reason Lat/Long is posted on the gates at airports is to program the INS (Intertial Nav System) - gyroscopes and accelerometers would measure every movement from gate to arrival and position was calculated but they needed precise lat long starting points. While in range of radio nav (over land basically) INS position and speed could be theoretically updated. INS being mechanical drifted over time but was pretty good at finding continents.

INS joined radio nav in the cockpit. GPS has now joined Radio Nav and INS. It took years and years and years for the FAA to approve GPS first for enroute nav and then for terminal and approach nav.

FANS is an acronym denoting "Future Air Navigation System." This a big bureaucracy defining standards for integration of nav systems. Also defining when nav systems differ in position, which one shoud the FMC (Flight Management Computer) trust.

As a side note - the Atlantic route has always been tough - packing as many flights in as possible has always been a goal. Airplanes started using reporting transponders (think AIS) years ago. This allowed reduced vertical flight path separation and the trailing separation because in the middle of nowhere - aircraft could "see" and avoid each other.

So - ask a simple question and someone around here will give a complicated answer. Bottom line is that aircraft have multiple methods for navigation and actually rely on no one method and each method probably has multiple redundant backups.

[colemj]

Originally Posted by boatman61

Ann.. reckon there's one or two pilots out there who like us remember life without the new technology..

So the planes would land safely, but it is unlikely they could be reloaded, turned around and put back into the air.

So commercial air traffic is dead if the GPS is down. If only because the passengers couldn't find the airport...

Mark

[s/v Jedi]

Finding England is easy: just point a bit left of where the sun and moon come from and then when you see land, turn left and follow it until it starts raining and conditions become miserable. That's it.

[colemj]

Originally Posted by s/v Jedi

Finding England is easy: just point a bit left of where the sun and moon come from and then when you see land, turn left and follow it until it starts raining and conditions become miserable. That's it.

Problem is that if you are in the Pacific, this also works, but you become surprised that England gained so many mountains!

Mark

[K_V_B]

Originally Posted by boatman61

Ahahahahaaaa....
Ann.. reckon there's one or two pilots out there who like us remember life without the new technology..

I remember flying with a friend in a Piper Cherokee when a problem with the alternator developed. In order to save the batteries he just switched of everything that consumed electricity.
We were flying VFR of course, and I was quite surprised to learn that for IFR you weren't even required to have a radio on board. All you basically need is airspeed, altimeter and a compass. And engine instruments.
We then flew on, and close to the the airport he switched the systems back on, and radios in a request to land. If he hadn't been able to get his radio working he would have had to deviate to a different airfield, as landing without contact with the tower is frowned upon on bigger airports.
On smaller fields it's no problem at all to come down without announcing yourself. In France for example there are lots of small fields where, if you'd try to contact them before landing you would be quite unlikely to ever get an answer. There you just fly your pattern, watch for other traffic and just put the plane down.
I assume that anybody with CPL to TPL would know how to do this as well...

Myself, my first long passages at sea were on a boat where we didn't have an engine or even electricity, let alone electronic navigation. The summum of electronic navigation at that time was the Phillips AP navigator, which used the DECCA system, but which our sailing school frowned upon (and couldn't afford anyway...)

[barnakiel]

I got corrected:

The second WPT is at dec, not at alt!

Alt is what will get compared to dist to obtain our towards or away.

barnakiel

[barnakiel]

And I got asked by another member:

"Alt without a sextant."

Grab your smarthone or any other digital camera and snap a picture towards the sun (use a filter).

Try to hold the camera 90degs to sea level, either vert or horiz.

From the camera's lens and pix count calculate the camera's lines per degs ratio.

In the image, calculate the lines from the sun to the horizon.

Convert to degs.

Here you are.

b.

[casablanca]

GPS going down? Or GPS receiver failure?

After 20 years of GPS the loss of signal is not an issue.

But radios fail for a variety of reasons so standby equipment is a sensible measure.

BUT the thread seems to overlook the world dependence on GPS for uses other than navigation. I work in the aviation industry and frequently come across the fear of "what if the US turns off GPS?"

GPS and in particular the timing associated with the GPS signal is now so ingrained in the fabric of life that this is never going to happen.

What we really need to worry about is not the GPS but the navigation charts. GPS will position us extremely accurately, but where are the rocks????? Much of the worlds waterways were surveyed in the days of sailing ships!


Bob
Casablanca Lagoon420

[Wotname]

Originally Posted by K_V_B

......
We were flying VFR of course, and I was quite surprised to learn that for IFR you weren't even required to have a radio on board. All you basically need is airspeed, altimeter and a compass. And engine instruments..........

Typo perhaps

VFR - no radios required
IFR - several radios required (comms and nav)