When GPS going down is no longer a theory

Richman

Well-Known Member
In this case, the problem was the insertion of a leap second. Some avionics suites could work without the GPS, others can’t. “Am I grounded or do I have to utilize an MEL procedure because this?” - that’s where the curiosity ends for most of us. As a pilot, I can’t program the GPS beyond entering a navigational course, nor am I going to Iowa and telling a Rockwell Engineer “You forgot to carry the 1, that’s why this is happening.” There are times to be curious, but inventing a new procedure while ignoring an established one is not the way to go about operating a part 25 airplane. Not to mention the liability involved by creating and using unapproved procedure.
Actually, there are very few things in this world more satisfying than telling an engineer they forgot to carry the one.

So while I understand that Des Moines doesn’t have the tourist draw of Vegas, you missed out on a experience of a lifetime.
 

CFI A&P

Exploring the world one toilet at a time.
Actually, there are very few things in this world more satisfying than telling an engineer they forgot to carry the one.

So while I understand that Des Moines doesn’t have the tourist draw of Vegas, you missed out on a experience of a lifetime.
One of these days I'll declare while I'm on J60 and drop in there to see what's going on.
 

Autothrust Blue

"...I know bait when I see it..."
Actually, there are very few things in this world more satisfying than telling an engineer they forgot to carry the one.
Agreed wholeheartedly. Also, I’ve been on the receiving end of a no-fault post-incident critique in a previous IT life. “This is still embarrassing enough that I won’t ever screw up the same way again.”
 

MikeOH58

Well-Known Member
You have to remember that OEM’s are looking to certify their jets as quickly and as cheaply as possible. The Challenger has a 18,000 foot limit for gear and flaps. Why? It isn’t structural or system related, that was just the highest altitude demonstrated for certification. I’d betcha the same for no MEL relief without a working GPS. Just wasn’t done during certification, and otherwise has no impact on the aircraft other then navigational purposes.

Of course all of this could be wrong, but I’d bet a donut.
 

woodreau

Well-Known Member
It’s been years since I’ve flown a CRJ, but the one time we had both FMSs MELd (it was pre-ADS-B so the transponder still worked) the FMSs wouldn’t update with GPS and it wouldn’t update DME/DME either, so other than at takeoff, the box had no idea where it was, we flew it green needles.

The biggest thing I had to do for that flight was to cover up the nav display MFD because it still displayed where the plane thought it was which was just drifting and was nowhere where the plane actually was. Just in the first year I’d flown the CRJ, that flight showed me how dependent I became on that nice “moving map” to see where I am.

It was easy back then to revert back to tuning in an onfield DME and fly it like I flew the 1900.

But I think now I’d be hard pressed to figure out how to do that on an Airbus. Well I know I can manually tune it on the radio management panel, but it would display on the ND so I can’t cover up the ND on the Airbus like I had to on the CRJ.
 

CoffeeIcePapers

Well-Hung Member
Sorry, been trying very hard to get it, ... but just. cannot. understand. ... ??? ... Please tell me I'm missing something. Even with the ARCDUs out, we still have a tune-able spare VOR receiver (3 required for Cat III at my shop) ... and that's all we ever had in the 80's. Can still navigate the whole continent with just one of those, right? Fly all kinds of approaches with LOC/ VOR, maybe NDB in Canada. WX is usually not at mins. everywhere at the same time ... FMS and GPS just sort of a nice toy, but not really essential to aviation ... ??? What am I missing???
Look up STARs in DTW. They're all RNAV.
Computer systems make it impossible for controllers to file non RNAV routes.
 

Autothrust Blue

"...I know bait when I see it..."
It’s been years since I’ve flown a CRJ, but the one time we had both FMSs MELd (it was pre-ADS-B so the transponder still worked) the FMSs wouldn’t update with GPS and it wouldn’t update DME/DME either, so other than at takeoff, the box had no idea where it was, we flew it green needles.

The biggest thing I had to do for that flight was to cover up the nav display MFD because it still displayed where the plane thought it was which was just drifting and was nowhere where the plane actually was. Just in the first year I’d flown the CRJ, that flight showed me how dependent I became on that nice “moving map” to see where I am.

It was easy back then to revert back to tuning in an onfield DME and fly it like I flew the 1900.

But I think now I’d be hard pressed to figure out how to do that on an Airbus. Well I know I can manually tune it on the radio management panel, but it would display on the ND so I can’t cover up the ND on the Airbus like I had to on the CRJ.
Yay for Rose VOR Mode.
 

Nark

Sheepdog
@Autothrust Blue
I’ve honestly never looked at the drift after a flight, per the FO shutdown flow. What’s the point if I have to align the IR’s anyway?
If they don’t align, it’ll tell me and at that point I’m going to do something about it. Reminds me about the air Asia flight out of Australia. I’ll have to read up about that later... seems fitting.

And if I have to explain constant descent angle one more time to a new-ish FO I’m going to petition for single pilot type rating in this bird.
 

Autothrust Blue

"...I know bait when I see it..."
I’ve honestly never looked at the drift after a flight, per the FO shutdown flow. What’s the point if I have to align the IR’s anyway?
Eh, you might have a leg where one of them has drifted far enough out that it warrants addressing. Anything bigger than a few NM of accumulated drift, and I'm reaching for the book (isn't it great that we have all of this stuff handy) to see how far out they are.

And a lot of people are willing to accept other peoples' crappy alignments, too.

And if I have to explain constant descent angle one more time to a new-ish FO I’m going to petition for single pilot type rating in this bird.
The thing about OEMAP is that it is technique, not procedure, but the simulator people apply it as if it is procedure, and it is written, so there ya are. Out on line, "do whatever you need to do" is a better guideline than whatever's written down (as in, if you think you need drag, I think you probably need drag). Downhill, flaps 2, 180 and idle is a good hack, but sometimes you just get screwed (FLL...) too, and wind up cooking along level in that configuration. Or you wind up high and hot and you quickly throw the OEMAP out the window and chase it :D

Generally speaking, any good visual approach involves an idle descent until more thrust is required to meet stabilized approach criteria--unless you have something else going. Which, there's always something else going.
 

BobDDuck

Island Bus Driver
Eh, you might have a leg where one of them has drifted far enough out that it warrants addressing. Anything bigger than a few NM of accumulated drift, and I'm reaching for the book (isn't it great that we have all of this stuff handy) to see how far out they are.

And a lot of people are willing to accept other peoples' crappy alignments, too.
I look at the drift because if it's more than a certain amount it gets written up, even if the next crew is going to be doing a full align.

Also, ain't no way I'm not doing a full reset of the ADRS every time. Maybe if it wasn't an etops leg...
 

Nark

Sheepdog
@BobDDuck we do 0 ETOPS legs. First time CA gets to the aircraft it’s full align, regardless of what’s going on. Subsequent legs, CA’s discretion.
 

BobDDuck

Island Bus Driver
@BobDDuck we do 0 ETOPS legs. First time CA gets to the aircraft it’s full align, regardless of what’s going on. Subsequent legs, CA’s discretion.
We only do ETOPs legs (with a few repo/ferry) exceptions. MX will do a full align as part of their etops checks... mostly. It's then on the PF's origination flow to reset them again. The problem we've been having, especially in Maui, is that the wind gusts will bounce the plane too much and one or two of the ADRS won't align the first (or second or third) try.
 

Derg

Cap, Roci
Staff member
There are plenty of things I couldn't do anything about in the cockpit that are useful to know.

I look at it like this, yeah there's 3 spheres, but they are:

Need to know
Nice to know
Trivia.

You know the "need to know" stuff to pass.your checkride, you know the "nice to know" stuff because you want recurrent to be easy, and you learn some of the trivia because you're a professional trying to learn everything you can about your craft.

Knowing that the engine has a variable geometry compressor might not allow you to actually change anything in flight, but the knowledge might help you make a decision if there is a condition that could be sensed that could imply that it failed. Even if not, I want to know how all this stuff works because I strap myself into these things and hurl myself around the country on them.

About 6 years ago, I was flying the same PC12 I'm flying now. One of our pilots had a pressurization failure where the aircraft wouldn't stop pressurizing. It would push up to the red line, the overpressure valve in the outflow valve would vent some pressure then it would do it again.

The checklist was followed, and guess what, nothing happened, it kept doing the same thing and the pilot couldn't get it to depressurize. Why? Well, the vacuum ejector to the boots had failed and that was upstream of the pressurization controller and Pilatus must've just never figured an ejector would fail and wrote no checklist to respond to this event. The end result? It was fine, the pilot descended then turned off of the environmental control system and waited for the cabin pressure to come down, then landed uneventfully. And yet a higher level of knowledge would have helped that pilot, instead of flying around in circles with a load of people for a half hour while he trouble-shot the problem, he could have said, "oh the dump valve doesn't work but the pressurization keeps working, the valve is stuck or the vacuum line has failed, guess I'm just going to have to shut it off."

We can do better than, "oh well I can't do anything about it so I don't need to know it." That's embarrassing - we should know as much about these things as we can.
I barely know what kind of engines my airplane has. How much thrust? I guess “enough”. Nothing I can do to change it and either they work or they do not and I call maintenance.
 

ppragman

FLIPY FLAPS!
I barely know what kind of engines my airplane has. How much thrust? I guess “enough”. Nothing I can do to change it and either they work or they do not and I call maintenance.
I get that I just disagree with that philosophy - I'm suggesting that it's in our best interest to know as much about our craft as we can. I don't really need to know much about weather, the TAF either says it's legal or not, and when I get to minimums I either see it or I don't. That doesn't mean I don't try to learn more about the atmosphere. I don't really need to know about the physics behind performance, it's either in the book, or it's not, but that doesn't mean I don't endeavor to know more about it.

With systems stuff, there's basically a direct relation to what you're doing every day at work. Why wouldn't you want to know more about how the pressurized metal tube carrying through the air works? You trust your life to it, and you are responsible to the people in the back - wouldn't they want you to know everything about the airplane you could? Isn't that part of our job? To be subject matter experts.
 

z987k

Well-Known Member
I get that I just disagree with that philosophy - I'm suggesting that it's in our best interest to know as much about our craft as we can. I don't really need to know much about weather, the TAF either says it's legal or not, and when I get to minimums I either see it or I don't. That doesn't mean I don't try to learn more about the atmosphere. I don't really need to know about the physics behind performance, it's either in the book, or it's not, but that doesn't mean I don't endeavor to know more about it.

With systems stuff, there's basically a direct relation to what you're doing every day at work. Why wouldn't you want to know more about how the pressurized metal tube carrying through the air works? You trust your life to it, and you are responsible to the people in the back - wouldn't they want you to know everything about the airplane you could? Isn't that part of our job? To be subject matter experts.
Nope, I have no curiosity about anything. I just show up, color a bit and go home.
 

Jordan93

Well-Known Member
Nope, I have no curiosity about anything. I just show up, color a bit and go home.
I have a little curiosity but not enough to play A&P. I’ve seen some pilots really get out of their lane by trying to play A&P. My job is to have adequate systems knowledge, run the QRH, and if the problem persists, call maintenance and have them fix or defer the problem. I love how some pilots try to diagnose the problem while our mechanics are on board.
 

z987k

Well-Known Member
This depresses me.
I think it's why NASA puts so much emphasis on Engineering and Science backgrounds for their pilot candidates. If you don't crave knowledge and just nerd out about the whole thing, want to do more than just push buttons, then something else might be more up your ally.
 
Top