Looks like a month of 'iffy' GPS service for the PNW. See:

Released
3 April, 2017
[b]FEDERAL AVIATION ADMINISTRATION
FLIGHT ADVISORY
GPS INTERFERENCE TESTING
FFC GPS 17-01 (FLEET FORCE COMMAND)
[/b]
6 April – 6 May, 2017
Bremerton, WA

GPS testing is scheduled as follows and may result in unreliable or unavailable GPS signal.

https://www.faasafety.gov/files/notices/2017/Apr/FFC_17-01_GPS_Flight_Advisory.pdf

A. Location: Centered at 474356N1224354W or the SEA VOR 300 degree radial at 25NM.

B. Dates and times:

6 APR 17 1300Z – 1559Z 1900Z – 2259Z
7 APR 17 0100Z – 0229Z 0500Z – 0759Z 1300Z – 1559Z 1900Z – 2259Z
8 APR 17 0100Z – 0229Z 0500Z – 0759Z
10 APR 17 1300Z – 1559Z 1900Z – 2259Z
11 – 14 APR 17 0100Z – 0229Z 0500Z – 0759Z 1300Z – 1559Z 1900Z – 2259Z
15 APR 17 0100Z – 0229Z 0500Z – 0759Z
17 APR 17 1300Z – 1559Z 1900Z – 2259Z
18 – 21 APR 17 0100Z – 0229Z 0500Z – 0759Z 1300Z – 1559Z 1900Z – 2259Z
22 APR 17 0100Z – 0229Z 0500Z – 0759Z
24 APR 17 1300Z – 1559Z 1900Z – 2259Z
25 – 28 APR 17 0100Z – 0229Z 0500Z – 0759Z 1300Z – 1559Z 1900Z – 2259Z
29 APR 17 0100Z – 0229Z 0500Z – 0759Z
1 MAY 17 1300Z – 1559Z 1900Z – 2259Z
2 – 5 MAY 17 0100Z – 0229Z 0500Z – 0759Z 1300Z – 1559Z 1900Z – 2259Z
6 MAY 17 0100Z – 0229Z 0500Z – 0759Z

C. Duration: Each event may last the entire requested period.

D. NOTAM INFO: NAV (FFC GPS 17-01) GPS (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL WI A 240NM RADIUS CENTERED AT 474356N1224354W (SEA 300025) FL400-UNL,
192NM RADIUS AT FL250
121NM RADIUS AT 10000FT
107NM RADIUS AT 4000FT AGL
95NM RADIUS AT 50FT AGL

E. Pilots are encouraged to report anomalies only when ATC assistance is required.

All good and well unless you fly an Embraer Phenom, at which point your plane will come from together


Sent from my iPhone using Tapatalk

Pilotage causes us to see things, on the surface, we didn't realize was there. GPS can cause us to miss some of the fun part of flying.

Not a problem, I always fly paper charts, the GPS is a backup. I'm probably a small minority for doing that, or maybe just getting old. On the other hand I don't worry about getting lost if the batteries die.

Paper exists in space and time.

I do not fly with or carry paper charts.

I fly with my iPad and iPhone. Both have ForeFlight loaded.

Before you say, "gotcha! They both rely on the same GPS signal!" remember that they are also electronic flight bags, and give you the ability to fly off a digital map just like you would on a paper one if you don't have a GPS signal. I also keep both charged from the plane's cigar lighter port.

One less thing for me to worry about keeping up-to-date.

iPad and iPhone double up on satellite systems, using both the US military GPS and the Russian GLONASS. Either one can quit and the other one will continue to give nav and location info to drive Foreflight. High end FMS systems like Honeywell Primus, CMC Esterline and the UNS have provisions for GLONASS input as well, prudent if the GPS system is prone to random willful disruptions.

It will be nice when all the GPS testing is no longer an issue. I can navigate with pilotage and ded reckoning as well as most people, but it's annoying as heck to have multi-thousand dollar boxes that can't be used to their full potential. Fortunately, I've never had any of them fail in IFR flight due to any of the periodic testing, but I've had them all stop GPS-ing in VMC. In IMC, I keep track of position with the VORs, too, so I could quickly revert to using them (or even my ADF!).

It seems to me that because GPS and GLONASS have been around for 20+ years, it's time to stop the testing. Surely by now DoD knows all there is to know about them!

Cary

stuff is kind of annoying for someone who has gotten lax and uses gps.... I have a bad elf pro, ipad pro, iphone7, and garmin aera onboard my plane at all times.. backups for backups... until gps in general isn't working!! probably should stuff some updated paper charts in the plane again just in case we had some of that testing going on here a while back..... anyone know the reason for what they are doing?

I have a friend directly involved in the testing program. He says it's classified. I don't know if he's joshing me or not.

Cary

interesting

Cary wrote:It seems to me that because GPS and GLONASS have been around for 20+ years, it's time to stop the testing. Surely by now DoD knows all there is to know about them!

Cary

It's not likely the satellites that are under test.

GravityKnight wrote:probably should stuff some updated paper charts in the plane again just in case

If the GPS signal is not useable, I would just plan on using your iPad and iPhone as if they were paper, and not worry about storing or keeping paper charts updated.

I originally had an ancient iPad that had a crappy GPS receiver in it. I was buzzing around with my Dad in the northern WA mountains one time and the signal was totally unusable so we just used my ForeFlight like it was a paper map and navigated via pilotage instead of looking for the ownship icon. Worked like a charm, and I knew the charts were up-to-date.

Just my technique.

CamTom12 wrote:

GravityKnight wrote:probably should stuff some updated paper charts in the plane again just in case

If the GPS signal is not useable, I would just plan on using your iPad and iPhone as if they were paper, and not worry about storing or keeping paper charts updated.

I originally had an ancient iPad that had a crappy GPS receiver in it. I was buzzing around with my Dad in the northern WA mountains one time and the signal was totally unusable so we just used my ForeFlight like it was a paper map and navigated via pilotage instead of looking for the ownship icon. Worked like a charm, and I knew the charts were up-to-date.

Just my technique.

oh .. derp... yea you bring up a good point... I think I should go back to bed... hopefully last blizzard of the year here!

I still like a whiskey compass, paper chart, and my wristwatch.

Besides, a rolled up sectional still makes the best funnel to use for dumping in a can of oil.




Gump

Lol, that's fair. You can only roll up an iPad once!

Cary wrote:I have a friend directly involved in the testing program. He says it's classified. I don't know if he's joshing me or not.

FWIW the VOR / DME location identified in the NOTAM is on or adjacent to the Navy Submarine Base at Bangor.
Home of the west coast fleet of Ohio-class nuclear missile boats (aka boomers).

Have seen that sort of testing here in NV over the years. Rumor is that they are testing (at least in part) ability to disrupt the GPS signal on purpose - I suppose to deviate all those N Korean missiles to CA where they belong instead of their intended targets in NV.

I never regretted my vertical card compass -
never more than a degree off at installation and calibration.
Compared it to my DG - and would use that compass if ever needed.

Whiskey compass always seemed to be going somewhere else,
or would get there before I did, or show up late for the show.

(mild hyperbole)

Yeah I could manage it- had to to get my ticket- but I like simple.

Chris C

CamTom12 wrote:

Cary wrote:It seems to me that because GPS and GLONASS have been around for 20+ years, it's time to stop the testing. Surely by now DoD knows all there is to know about them!

Cary

It's not likely the satellites that are under test.

True, but I'm thinking that using them has been around for long enough that whatever anomalies might exist would have been discovered by now, so that continued testing shouldn't be necessary. If we're all expected to use satellite navigation when we can't look out the window, it ought to be working well, but that should have been proven by now. Gosh, I'd hate to be on a tight LPV approach only a few hundred feet above the ground in IMC and have the GPS system suddenly glitch!

Cary