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Old 04-12-2019, 04:30 AM
  #7  
PurpleToolBox
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Originally Posted by rickair7777 View Post
Probably not jamming, at least not targeted at you. GPS jamming targeted at you would render it useless. GPS signals are very weak.

It might have been RF inteference, either authorized or unauthorized. Might also have been jamming targeted at something else nearby, depending on where you were when it happened. In the US they issue NOTAMs before they do that.
Originally Posted by aviatorhi View Post
What he described sounds exactly like GPS jamming where the FMS starts using other means of discerning aircraft position and ANP rapidly rises.

We were definitely in a area to be jammed. It is an area of known jamming. The company has issues several NOTAMs about it. The problem with our situation was that we were jammed much longer than the company had ever seen before.

The airplane reverted to INERTIAL for navigation, on the POS REF page the GPS position was blank. The RADIO line started tuning DME DME (which it doesn't do unless you lose GPS). We had all sorts of EICAS messages consistent with GPS being lost or jammed (ADS-B OUT L/R, TCAS, TERR POS). The ANP started increasing. I forget the maximum value but it did reach a couple of miles during that short amount of time.

Slowly the GPS signal started to come back and all the messages went away.

It was interesting to watch. Safety reports filed after landing.
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