[time-nuts] Loran C sounds

[Peter Putnam]

Greetings,

As a former user of Loran for aircraft navigation, I can safely say that 
there is no reason to preserve the system.

The antenna required on an aircraft must be vertically polarized and of 
significant length. The route from the US west coast to Hawaii had no 
coverage in the middle one-third of the route at night. Coverage was 
even less during daylight hours.

Cycle slipping was always an issue; one needed to have a dead-reckoning 
position available to make sure the Loran-derived position was accurate. 
Errors of hundreds of miles (that pop back to zero without warning) were 
seen on the TI 9000 unit, a $1500 box, that displayed only time 
differences. Calculation of the flight log was a separate time consuming 
effort.

Coverage in the Southern Hemisphere was  not available. My A-10 aircraft 
bubble-sextant and Tamaya NC-2 sight-reduction calculator served me well 
in that half of the world.

Now I can have a position update once per second, accurate to a few 
meters, anywhere in the world, with no antenna issues, in a hand-held 
GPS receiver requiring no power from the aircraft, that automatically 
updates the time to each fix along the route, for under $100.

Good-bye to Loran C and Loran A, too, which had even worse problems with 
skywave contamination of the groundwave signal. Plotting a position on 
paper charts overprinted with hyperbolic lines wasn't particularly 
accurate anyway, especially along the baseline of a chain.

Regards,
Peter



Bob Camp wrote:
> Hi
>
> I know it's a chicken and egg thing, but Loran-C died for navigation a while back. The hardware simply isn't out there anymore. GPS could have died two weeks ago and Loran-C would have not helped the navigation people. They don't have the receivers in place. A backup that nobody is set up to listen to is not a backup.
>
> Keeping Loran-C in the critical care ward forever would have not helped navigation. The only thing that would have helped was a significant upgrade to the system. You have to wonder if anybody would put the gear in place  after an upgrade. Even with cheap electronics, the antenna install on Loran drives up the cost. Production volume on the GPS electronics does will always make a low use system like Loran expensive.
>
> The backup for most (but not all) navigation users is the mark one eyeball. Don't even joke about the modern world navigating with a sextant. I've handed mine to a number of people and gotten a blank look in return ....
>
> The thing that will keep SA turned off is competition. If bad people have three systems to pick between, they will switch to the one that works for them. No advantage to SA in that case. On the other hand, if you turn on SA, lots of voters complain about it. It's a lot harder for them to switch.  
>
> Personally, I'll miss Loran-C. It was a very useful thing to have. I have used Loran a lot, but never for navigation. Like it or not, Loran is a nav system not a timing system. Without upgrades, Loran is a second rate nav system. 
>
> Are we very dependent on GPS - yup. That didn't change one bit when they turned Loran off. Ignore the navigation stuff completely. The world of timing is now based on GPS. That's been true for years. Trying to get a backup into those networks is a futile effort. A lot of us have tried and failed. The problem has not been ignored, it's been mentioned again and again. There's been an informed decision that GPS is "ok". I disagree with that, but the decision was not made in an information vacuum. Changing that decision and implementing the change would take decades, not weeks or months. You could build a GPS system from scratch in less time than it would take to finally put in backups at all those timing nodes. 
>
> We live in a fragile world. There are a lot of systems we depend on. Take a look at how New York City gets it's water supply. That's at least as scary as GPS. The world is full of single point of failure issues ....
>
> Bob
>   
>