Originally Posted by Idiens
midlifesailor – You raise a lot of interesting points. Why would the FAA adopt LORAN for transport aircraft when it already has NDB, VOR and DME aids to navigation with GPS/WAAS now added on top?
I think LORAN receivers
are also not immune to jamming, the military have the capability already. E-LORAN will be no use to existing General Aviation LORAN receivers, so new ones would need to be bought, would GA like that? Will they be mandated to carry ADS-B? Will it be UAT or Mode-S based or both? I see trilateration is also making a bid for radar’s surveillance crown.
I would not bet on the FAA adopting LORAN any time soon. It is ironic that the FAA be paid by congress study a USCG system, LORAN, for aviation; while the mariners happily use the FAA’s WAAS and sales of RTCM differential receivers are dropping. Conversely, the take-up of WAAS by air transport is currently zero. It’s an odd world.
The technolgies you are talking about stem almost from the dawn of air navigation. They are are horrendusly expensive to maintain and are rapidly becoming obsolete. NDB's are being phased out as fast as the FAA can make it happen. No commecial aircraft, and fewer and fewer GA aircraft are equipped with an ADF reciever for NDB navigation and DME is also rapidly becoming cost ineffective to maintain in a GA airplane. VOR navigation will soon follow the path of the four course range and NDB before it. GPS/WAAS/LAAS won't be piled on top of anything in the future. The ground based stuff, including ILS will go away over time. Loran may not be the answer for a back up to GPS, but until we have an answer, I'd argue we should keep the system active. I'm not sure were you got the idea WAAS was not being used for aviation. The Big Iron is using it, and Garmin has had one WAAS certified unit on the market for about 3 years and recently got upgrade approval for their top selling GNS400/500 series units.
As far as ADS-B, Yes, a mandate is comming. Even AOPA supports it. As to UAT vs. 1090ES, that decsion hasn't been made yet, but its shaping up to be both. UAT as proven itself in Alaska under the Capstone project in GA aircraft, but all new airliners are being delivered with 1090ES capabilty. The FAA ground stations will likely be capable of receiving both and the systems will most likely integrate both types. To soften of the sting of the equipment mandate for GA, the FAA is offering traffic and weather data on the UAT uplink.
BTW, Multi lat will not be the answer for en route, terminal and approach surveillence. Automated Dependent Surveillence - Broadcast (ADS-B) will. Multi lat will only be part of some surface surveillence systems like ASDE-X, but even that may be quickly supplanted beacause ADS-B works on the ground as well as in the air.
As to the succeptablity of GPS to jamming, the FAA is moving towards GPS based CAT II and CAT III approches. A jamming event would not need to be widespread or prolonged to result in a catastophic event with an aircraft like an A380 in a zero zero landing situation. An ADS-B system that was able to use either GPS or Loran for its postional data would require both to be jammed at the same time, which would at lest make it a more difficult propostion.
Lastly, I seriously doubt we are as prepared to deal with a localized jamming situation as our government would like us to believe.
Perhaps Loran will never again be popular with boaters, but if the system were going to be around, new products might be introduced that would be as accurate and reliable as GPS.