Originally Posted by Freight Dawg
(Post 2802218)
The concern over jamming really doesn't apply to us airline guys. We've got plenty of backups. The concern is for the average GA dude. The FAA has been pushing next gen nav, decommissioning VOR's and NDB's and mandating ADS-B. This has pushed most (?) GA guys to use GPS as their primary, or in some cases only, nav. I've personally witnessed probable GPS jamming outside of NOTAMed air space. So if the military is playing nearby is all GA traffic grounded? If a pilot is near the NOTAMed airspace and is accidentally jammed. Is he a primary target only due to his jammed ADS-B transponder? We're going to a single source for nav options. Personally, I feel it's problematic. But who could have seen this coming......
Sure it is a concern. Backups? What happens when you lose GPS updating? You revert to inertial and radio updating (I can speak only for 777 and probably most Boeings). Yes, there's still a navigation solution being calculated. However your operations become greatly degraded. You can't fly in RNP4, RNP2, FANS (depending on location), or ADS-B require airspace. You can't fly any procedures that require GPS. Since writing my first post on the subject above, on my last flight we had GPS jamming indications over Eastern Montana/Western South Dakota. I checked the POS REF page and sure enough we were back to radio updating. It didn't cause any further issues other than some safety paperwork to be filed. |
Originally Posted by PurpleToolBox
(Post 2804447)
Sure it is a concern. Backups?
What happens when you lose GPS updating? You revert to inertial and radio updating (I can speak only for 777 and probably most Boeings). Yes, there's still a navigation solution being calculated. However your operations become greatly degraded. You can't fly in RNP4, RNP2, FANS (depending on location), or ADS-B require airspace. You can't fly any procedures that require GPS. Since writing my first post on the subject above, on my last flight we had GPS jamming indications over Eastern Montana/Western South Dakota. I checked the POS REF page and sure enough we were back to radio updating. It didn't cause any further issues other than some safety paperwork to be filed. |
Originally Posted by Freight Dawg
(Post 2804925)
Please reread my first three sentences. The concern isn’t for Boeing guys, it’s for light aircraft. Many Cessna, Pipers, etc have very limited backups, if any. Due to the ADS-B mandate, during a GPS outage their position will only be know by primary radar. All transponder, including Mode C, functions will be inoperative.
My point was I don't see it as a concern for just light aircraft. |
Originally Posted by Freight Dawg
(Post 2802218)
The concern over jamming really doesn't apply to us airline guys. We've got plenty of backups. The concern is for the average GA dude. The FAA has been pushing next gen nav, decommissioning VOR's and NDB's and mandating ADS-B. This has pushed most (?) GA guys to use GPS as their primary, or in some cases only, nav. I've personally witnessed probable GPS jamming outside of NOTAMed air space. So if the military is playing nearby is all GA traffic grounded? If a pilot is near the NOTAMed airspace and is accidentally jammed. Is he a primary target only due to his jammed ADS-B transponder? We're going to a single source for nav options. Personally, I feel it's problematic. But who could have seen this coming......
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Originally Posted by Freight Dawg
(Post 2804925)
Please reread my first three sentences. The concern isn’t for Boeing guys, it’s for light aircraft. Many Cessna, Pipers, etc have very limited backups, if any. Due to the ADS-B mandate, during a GPS outage their position will only be know by primary radar. All transponder, including Mode C, functions will be inoperative.
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Originally Posted by PurpleToolBox
(Post 2805442)
My point was I don't see it as a concern for just light aircraft.
Cheers |
Originally Posted by pangolin
(Post 2805447)
I think you are wrong about mode C being inoperative. When I was in a known jammed area I asked atc if they had our ADS -B and they said no but they still had mode C.
GPS signals are pretty weak, I don't know for sure but strongly suspect that mode C (and other modes) will take more power to jam than GPS. GPS is probably always going to be the weak link in terms of which systems are susceptible to jamming or other interference. That and sat based wifi :rolleyes: |
Originally Posted by Freight Dawg
(Post 2804925)
Please reread my first three sentences. The concern isn’t for Boeing guys, it’s for light aircraft. Many Cessna, Pipers, etc have very limited backups, if any. Due to the ADS-B mandate, during a GPS outage their position will only be know by primary radar. All transponder, including Mode C, functions will be inoperative.
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The “backup” plan is still ground-based navigation, VOR’s. With NextGen implementation, there is a Minimum Operational Network (VOR MON) that will be maintained. For FMS that revert to DME/DME/IRU updating with the loss of GPS, there will also be aMinimum number of DME stations
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Originally Posted by PerfInit
(Post 2805728)
The “backup” plan is still ground-based navigation, VOR’s. With NextGen implementation, there is a Minimum Operational Network (VOR MON) that will be maintained. For FMS that revert to DME/DME/IRU updating with the loss of GPS, there will also be aMinimum number of DME stations
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