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AVmail: April 26, 2010

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Each week, we run a sampling of the letters received to our editorial inbox here in AVmail. One letter that's particularly relevant, informative, or otherwise compelling will headline this section as our "Letter of the Week," and we'll send the author an official AVweb baseball cap as a "thank you" for interacting with us (and the rest of our readership). Send us your comments and questions using this form. Please include your mailing address in your e-mail (just in case your letter is our "Letter of the Week"); by the same token, please let us know if your message is not intended for publication.

Letter of the Week: The Question of LORAN

Your "Question of the Week" missed the point.  What is needed for a GPS backup is E-LORAN (which uses the LORAN-C infrastructure).  The upgrade and implementation of E-LORAN (Enhanced LORAN) was almost complete before the current government reversed several past Congressional decisions.  E-LORAN is almost as accurate as GPS (within feet).  A complete E-LORAN system in the U.S. costs less than one GPS satellite.  E-LORAN has been able to be fully intergrated into a GPS receiver to give it complete navigation redundancy.  That is why 13 other countries in the world will not shut down their E-LORAN systems.

The correct answer to your question is Don't shut down LORAN, but finish upgrading it to E-LORAN so inexpensive GPS/LORAN combo receivers can be used for position, navigation, and timing.

U.S. government studies have already found E-LORAN to be the best backup for GPS.  GPS is a high frequency, very low power, easily jammed signal.  LORAN is a low frequency, very high power signal that is hard to jam and covers the entire U.S. and a lot of the world.  It is the only system that is almost as accurate as GPS for position — and actually more accurate for timing.

The government just threw away $156 million in already completed E-LORAN upgrades and will spend $200 to $500 million to dismantle the LORAN system in order to save the $25 to $36 million cost per year to finish the upgrades and operate the entire U.S. LORAN system.

This is a highly technical issue that most people don't understand (especially in Congress). GPS failures were predicted to start occuring in 2010, and GPS replacements are currently over budget and overdue.  GPS is used not just for position and navigation, but also for timing, which allows things like cell phones, pagers, and ATMs to work.

National security is also at stake when a receiver relies on only one type of signal like GPS that is so easily jammed. With E-LORAN being so hard to jam (and transmissions based on U.S. soil and not in space), a combo GPS/E-LORAN system would prevent a terriorist shut down of something so important to the operation of this country.  GPS satellites have a life expectancy of 10 to 15 years.  The current GPS system is at its end of life.  The LORAN system is a chain of high-power transmitters located at installations run by the U.S. Coast Guard.

When looked at honestly, there is no technical, cost, or security reason to shut down the LORAN system.  Each of those only provide reasons to maintain the LORAN system like the rest of the LORAN users of the world have decided to do.

Miles Muller

I participated in the AVweb poll, and even though the majority said LORAN should be revived, I was surprised that a number of pilots said no!

To me, this says that many pilots do not understand how vulnerable the GPS system is, nor the ramifications of a system failure.

If the FAA, the Coast Guard, the avionics manufacturers, and the aviation community had planned for retention of LORAN-C, then it is likely the capability would have been built into most new GPS boxes.  All it would require would be an additional front-end receiver chip, an antenna, and additional database capability.

Even very recently, a large number of GA aircraft still had LORAN boxes installed and working, providing GPS backup capability for that time when the GPS system goes down.  And it will.

This becomes more and more important as the VOR and ILS systems move into retirement.  They are very, very expensive to operate and maintain, and with the GPS system being phased in, the old systems will increasingly be seen as unnecessary.

GPS is absolutely wonderful, but it is also very vulnerable. A major solar storm, a military shutdown during an attack (or for other security reasons), or even an improper software upload could bring down one or even all the satellites for a short (or even a long) time.

Remember the big telephone blackout a number of years ago?  My understanding is that it was caused by a software upgrade that was loaded to many switching centers.  When the bug hit sometime later, it took down telephone communications across areas comprising much of the east coast and adjacent regions.

Imagine being in your plane on vacation with your family in the mountain states, climbing out from a remote airport at night, and suddenly losing all GPS capability — and being too low for VOR navigation or radar surveillance.

If you don't believe me on GPS vulnerability, please read the following information from the U.S. Department of Defense perspective:

http://www.gpsworld.com/defense/loran-what-president-meant-say-was-9127

Also visit and study the information at LORAN.org.

LORAN-C provides a comparatively dirt cheap way to maintain at least some ground-based, less vulnerable navigation capability for general aviation.  If we commit to retain it, then the avionics manufacturers will include it in their systems.  And we will be better positioned for the adoption of the newer E-LORAN system being worked on by Great Britain, among others.

If the Coast Guard can't maintain the system, then we in the aviation community should insist that the FAA take it over. The cost would be a tiny drop in the FAA budget for a system that may well prove indispensable one day.

Rol Murrow
Wolf Aviation Fund

Great timing for the LORAN shutdown. How many hundreds of millions of dollars will it take for one new WAAS satellite for "redundancy"? The NorthStar M1A LORAN in my panel had been working just fine for decades, where the costs of maintaining the ground stations was measured in a few tens of millions of dollars.

Mike McHugh

Should LORAN-C be revived, or should E-LORAN (Enhanced-LORAN) be implemented? is a far better question.

E-LORAN provides near-WAAS precision, is ground-based, is not affected by solar flares, and can be implemented at existing facilities by upgrading equipment.

Dr. Charles Truthan

It seems to me that the question of keeping LORAN-C as a back-up to GPS is pretty moot unless aircraft are equipped with LORAN-C receivers.  How many aircraft currently operate with LORAN-C capability?  And are the aircraft systems that are installed IFR-capable and certified?  Having the transmission side of a navigation system without the reception side is as useless as a write-only hard disk on a computer.

Van Swofford


Kudos for Van West

I found Jeff Van West's video on Garmin 430 tips very useful. The activate legs trick is something I will undoubtedly use in my flying. I am working on my IFR certification, and for my training, I fly round robin flights regularly, in which I go to two or three airports and fly approaches. I had been trying to figure out how to load the airports into a flight plan and then activate approaches at each airport. Jeff's video finally answered the question.

Keep up the good work.

Mahesh Sankaran

This guy's work is terrific and just what's needed for the IFR pilot. Please expand his work on AVweb.

Howard Goldstock

AVweb Replies:

Jeff is Editor-in-Chief of IFR magazine and Managing Editor of Aviation Consumer magazine in addition to his contributions to AVweb.

Russ Niles
Editor-in-Chief

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