When GPS going down is no longer a theory

Roger Roger

Paid to sleep, fly for fun
You can type in coordinates, tune DME/DME or order a pizza through the FMS, but you won’t even get that far. The manufacturer does not allow you to defer all of the GPS in this airplane (the CL30 & CL35 series). If you’re flying that model and affected by this, then you’re done. Don’t even bother starting the APU. Not all airframes are impacted, but a large number that have a specific part number installed.

The tail I was flying (CL30) is not equipped with the now known GPS component and therefore was immune to this, and as a result I was flying over the last couple days. Other model aircraft maybe flying because they have relief in the MEL, such as the CRJ or whatever if they’re allowed deferral of the GPS system.
Right but, why are you not allowed to defer? Is it connected to so many other systems that the jet is just un-dispatchable? If so that’s pretty screwed up.
 

CFI A&P

Exploring the world one toilet at a time.
Right but, why are you not allowed to defer? Is it connected to so many other systems that the jet is just un-dispatchable? If so that’s pretty screwed up.
Because the manufacturer doesn’t permit it. As much as I’d like to give you a better answer, I don’t know and frankly wasn’t concerned. Mine worked, so I flew but others in the fleet had an issue and it was a NO-GO.

Figuring out how it happened, how to fix it, and re-write the MEL is above my pay grade. I was ready to go back to the hotel if it didn’t boot up normally.
 

BobDDuck

Island Bus Driver
Right but, why are you not allowed to defer? Is it connected to so many other systems that the jet is just un-dispatchable? If so that’s pretty screwed up.
You can't defer it because it's not in the MMEL. Who knows what is is connected to, but the OEM decided it wasn't deferable... so it's not.
 

Roger Roger

Paid to sleep, fly for fun
Because the manufacturer doesn’t permit it.
You can't defer it because it's not in the MMEL.
Well no crap. :rolleyes:

You don’t think guys flying those planes maybe should be a little curious why the manufacturer deemed a loss of GPS to be so critical the plane can’t dispatch without it? Like maybe to have an idea what would happen if GPS was lost enroute? Not that that could happen, GPS failures and whatever other systems are connected that the manufacturer didn’t see fit to tell pilots about only happen on startup.

@Autothrust Blue , @ppragman , am I taking crazy pills or should people care about this?
 

Autothrust Blue

"...I know bait when I see it..."
Well no crap. :rolleyes:

You don’t think guys flying those planes maybe should be a little curious why the manufacturer deemed a loss of GPS to be so critical the plane can’t dispatch without it? Like maybe to have an idea what would happen if GPS was lost enroute? Not that that could happen, GPS failures and whatever other systems are connected that the manufacturer didn’t see fit to tell pilots about only happen on startup.

@Autothrust Blue , @ppragman , am I taking crazy pills or should people care about this?
I find most pilots have little in the way of curiosity, frankly.

Which is fine, to a point.
 

CFI A&P

Exploring the world one toilet at a time.
Well no crap. :rolleyes:

You don’t think guys flying those planes maybe should be a little curious why the manufacturer deemed a loss of GPS to be so critical the plane can’t dispatch without it? Like maybe to have an idea what would happen if GPS was lost enroute? Not that that could happen, GPS failures and whatever other systems are connected that the manufacturer didn’t see fit to tell pilots about only happen on startup.

@Autothrust Blue , @ppragman , am I taking crazy pills or should people care about this?
I get what you’re saying, but in a situation like this - if the books say I need at least 1 funcitioning GPS and 0 are functioning - then I’m S.O.L. Especially with a programming problem such as this with the GPS/ FMS, it’s going to take someone from the manufacturer to figure that one out. In fact, before I did the first flight after this problem surfaced, I called a friend that was flying when it quit and got the rundown. Since my unit booted up fine, I was dispatched and flying while Rockwell Collins/ Bombardier/ Transport Canada/ FAA & our POI was still trying to fully understand the situation and come up with a solution. Like any other GPS failure, you start getting vectors until you get the VOR to VOR set up and tracking. Another make/ model aircraft can dispatch with 0 if following a specified procedure, but we don’t have said procedure. If we did, I know how that would work (DME/DME). It still has two engines, two wings, and gas in the tanks; so I know it will physically fly but it couldn’t because of paperwork.
 

MikeD

Administrator
Staff member
Well no crap. :rolleyes:

You don’t think guys flying those planes maybe should be a little curious why the manufacturer deemed a loss of GPS to be so critical the plane can’t dispatch without it? Like maybe to have an idea what would happen if GPS was lost enroute? Not that that could happen, GPS failures and whatever other systems are connected that the manufacturer didn’t see fit to tell pilots about only happen on startup.

@Autothrust Blue , @ppragman , am I taking crazy pills or should people care about this?
MEL stuff aside, can the INS/INU not operate independently of GPS with whatever acceptable drift component it would have, like INSs used to do before GPS ever existed? Or will it not work at all without it. That’s what I’m curious about....a technical question.
 

CoffeeIcePapers

Well-Hung Member
MEL stuff aside, can the INS/INU not operate independently of GPS with whatever acceptable drift component it would have, like INSs used to do before GPS ever existed? Or will it not work at all without it. That’s what I’m curious about....a technical question.
Yes, it will work without it. You can update your position using navaids. If you enable auto-tuning on the radio tuning units, it will automatically update itself.
 

MikeD

Administrator
Staff member
Yes, it will work without it. You can update your position using navaids. If you enable auto-tuning on the radio tuning units, it will automatically update itself.
Yeah some of the older 737s have that feature. I’m guessing some of these newer planes either don’t have that, have it but aren’t authorized to rely on it, or don’t have any other non-GPS update capability? Hence why not allowed?
 
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Autothrust Blue

"...I know bait when I see it..."
MEL stuff aside, can the INS/INU not operate independently of GPS with whatever acceptable drift component it would have, like INSs used to do before GPS ever existed? Or will it not work at all without it. That’s what I’m curious about....a technical question.
Most CRJs are not equipped with inertial navigation, and as such are DME-DME only sans GPS.
 

CoffeeIcePapers

Well-Hung Member
Yeah some of the older 737s have that feature. I’m guessing some of these newer planes either don’t have that, have it but aren’t authorized to rely on it, or don’t have any other non-GPS update capability? Hence why not allowed?
Yeah, it depends on the exact components that were installed. It varies, even among aircraft that are the same type.
 

tbflyer

Well-Known Member
The only problem with that technique is that if there is no GPS position in the CL30 & CL35 series, then you’re grounded. The MEL requires at least 1 GPS and does not allow for using DME/DME for position locating.
That sucks, I know I’m the CRJ you can type in an airport code then copy the airport location to the pos init position, we can also fly dme/dme
 

CFI A&P

Exploring the world one toilet at a time.
That sucks, I know I’m the CRJ you can type in an airport code then copy the airport location to the pos init position, we can also fly dme/dme
Which has been brought up several times while discussing this. “But on the ____, we can do (insert procedure or technique).” “That’s great, we don’t fly the CRJ and are restricted by a different MEL.”

We can enter LAT/LONG and create a waypoint all day, that’s how we insert ETPs into our route when Class II.

Even if it was deferrable, it would limit the capability of the aircraft. No Class II, no RNAV SIDS/ STARs/ approaches, it is tied into the EGPWS, so no mountainous airports... Handicapping the aircraft like that is a little bit of a problem when operating under 135.
 
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ppragman

FLIPY FLAPS!
Which has been brought up several times while discussing this. “But on the ____, we can do (insert procedure or technique).” “That’s great, we don’t fly the CRJ and are restricted by a different MEL.”

We can enter LAT/LONG and create a waypoint all day, that’s how we insert ETPs into our route when Class II.

Even if it was deferrable, it would limit the capability of the aircraft. No Class II, no RNAV SIDS/ STARs/ approaches, it is tied into the EGPWS, so no mountainous airports... Handicapping the aircraft like that is a little bit of a problem when operating under 135.
Where on God's Green Earth would you fly a CRJ under class 2 nav? The Carribean?
 

ppragman

FLIPY FLAPS!
Well no crap. :rolleyes:

You don’t think guys flying those planes maybe should be a little curious why the manufacturer deemed a loss of GPS to be so critical the plane can’t dispatch without it? Like maybe to have an idea what would happen if GPS was lost enroute? Not that that could happen, GPS failures and whatever other systems are connected that the manufacturer didn’t see fit to tell pilots about only happen on startup.

@Autothrust Blue , @ppragman , am I taking crazy pills or should people care about this?
People should be extremely concerned about why.
 

jtrain609

I'm a carnal, organic anagram.
Which has been brought up several times while discussing this. “But on the ____, we can do (insert procedure or technique).” “That’s great, we don’t fly the CRJ and are restricted by a different MEL.”

We can enter LAT/LONG and create a waypoint all day, that’s how we insert ETPs into our route when Class II.

Even if it was deferrable, it would limit the capability of the aircraft. No Class II, no RNAV SIDS/ STARs/ approaches, it is tied into the EGPWS, so no mountainous airports... Handicapping the aircraft like that is a little bit of a problem when operating under 135.
YEAH, BUT!!!
 
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