Cessna172 with classic gauges - DME

[PTI139 135]

So if I understand that the only way to measure the distance to a VOR or ILS beacon is to chosse a „Direct“ to the VOR in the GPS.

Simulataneously following a GPS flightplan an measuring the distance to a VOR is not possible in this configuration.

If DME is so superflouous in modern navigation I wonder why it is still used in modern devices like G3000 or Airliner nav equipment.

[Lotharen 287]

3 hours ago, Chock said:

Recently, sunspot AR2770 has been affecting GPS signals on Earth, and this could of course affect radio signals too, but if you have more than one system, you're potentially in a better position to perhaps avoid disruption to navigational signal integrity.

Sunspots actually make radio communication better, at least in the HF bands. 🙂

[Chock 17,769]

46 minutes ago, Lotharen said:

Sunspots actually make radio communication better, at least in the HF bands. 🙂

Exactly.

[FPStewy 538]

2 hours ago, PTI139 said:

Simulataneously following a GPS flightplan an measuring the distance to a VOR is not possible in this configuration.

You can some sort of way do it in the G1000 or G530 just select the nearest VOR you'll see all distances to VOR's even the low ones. It just ain't right 😞

[Victoroos 205]

4 hours ago, Chock said:

As a film nerd aside to this, for those of you who like to ruin movies with facts, in the movie Independence Day, the plot sees Jeff Golblum's character David, as an engineer who is familiar with communications satellites. He determines that the invading aliens are using the Earth's own GPS satellites to aid in the coordination of their assault.

Leaving aside the deus ex machina plot device whereby spaceships in the movie apparently have an operating system which allows Apple's OS7 to connect with them wirelessly, a wider plot problem is that in a scenario where countries are under threat, one of the first things military organisations do, is jam satellite navigation systems over their own territory so they cannot be used to aid an enemy attack. 🤣

Interesting to note that one thing they do get right in that movie given all this, is that with normal comms down, they start contacting one another using morse code on traditional radios.

yupp, I'm that kind off guy as well, hehehe. I'll remember next

[FlyingInACessna 656]

3 hours ago, bonchie said:

4 hours ago, GearUp180 said:

 

You think no one says third world country anymore? Gonna highly disagree and leave it at that.

I think the US is late on this one, but yes, it is being phased out as an improper term, much like the word “Indian” was phased out as a means to describe a Native American (because it makes no sense). The correct phrase today is “developing nation,” and I agree with its usage over third-world country, a phrase coined in the time of the Cold War to name nations that weren’t aligned with either the east or west blocs (which again makes no sense).

[HighBypass 2,339]

15 minutes ago, FlyingInACessna said:

...The correct phrase today is “developing nation,” ...

The trouble is that many "developing nations" have sub-optimal governments or rulers who do not allow any developing... 

GPS for a distance to a VOR? If the VOR in question is part of your magenta line i.e. a waypoint then the distance to it will be displayed at the very least when you begin to fly the leg to that VOR.

[SAS443 1,728]

4 hours ago, Chock said:

the aeroplane's systems also check the position by triangulating radio beacon signals, as these can improve the integrity of the positional data the thing has and speed up the INS spin up, particularly when in areas with GPS signal degradation, or latitudes where the Earth's rotation will otherwise mean a long INS spin up time, potentially of up to fifteen minutes.

There is no way of intervene with an inertial Navigation System's alignment cycle? It only uses earth rotation speed and gravity in order to determine

• True North (parallell of Earth rotation axis) 
• Local vertical (used for determine attitude)

Alignment is completed when true North direction has been calculated. An INS is like PMDG "It's done when it's done". It needs its precious time 🙂 

5 hours ago, Der Zeitgeist said:

How much are VORs and NDB even used in real-life flying these days?

Declining more and more for each year

But still mandatory in both PPL and ATPL courses. And flying charter into smaller greek islands you can count on getting VOR approaches and even NDB

 It is actually funny to see the brand spanking new  Flight School DA42's with their fancy glass cockpits shooting NDB approaches at my local field 😆

 

[bonchie 2,305]

53 minutes ago, FlyingInACessna said:

I think the US is late on this one, but yes, it is being phased out as an improper term, much like the word “Indian” was phased out as a means to describe a Native American (because it makes no sense). The correct phrase today is “developing nation,” and I agree with its usage over third-world country, a phrase coined in the time of the Cold War to name nations that weren’t aligned with either the east or west blocs (which again makes no sense).

I really don’t care enough.

Edited August 30, 2020 by bonchie

[Chock 17,769]

4 minutes ago, SAS443 said:

There is no way of intervene with an inertial Navigation System's alignment cycle? It only uses earth rotation speed and gravity in order to determine

• True North (parallell of Earth rotation axis) 
• Local vertical (used for determine attitude)

Alignment is completed when true North direction has been calculated. An INS is like PMDG "It's done when it's done". It needs its precious time 🙂 

 

There are in many ways the INS it is tweaked by radios. Here's a couple of specific ones...

During alignment, the input fields on the INS equipment flash, and the PFD flashes as well on some aeroplanes, this is to get you to remind you to put in the gate/stand coordinates to help speed up the alignment process. If you do, these coordinates are cross referenced with radio beacon signal data, if available to check accuracy. If none of that info is forthcoming, then the INS does the full laborious align calculation based on the Earth's rotational drift speed at the point on its surface which you are on, in combination with magnetic variation and a heading calculated from that. There's not much you can do about the rotation aspect of it, since you can't speed up the Earth, but the magnetic variation calculations can eliminate some magnetic anomaly possibilities caused by some locations on Earth, if they are able to have a bit of a clue as to a a starting point, based on radio triangulation.

A more interesting one with regard to radios tweaking the INS/IRS position, occurs at the point where you go on the runway and line up for take off. When you hit TOGA and the throttles move, this sends an updated position to the aeroplane's nav systems based on how far you are from the ILS signal transmitters. This is very accurate information indeed because you are typically dead centre of the concrete right near the piano keys and on a very specific known magnetic heading, which updates as an INS drift correction.

[ark 1,294]

21 minutes ago, Chock said:

There are in many ways the INS it is tweaked by radios. Here's a couple of specific ones...

During alignment, the input fields on the INS equipment flash, and the PFD flashes as well on some aeroplanes, this is to get you to remind you to put in the gate/stand coordinates to help speed up the alignment process. If you do, these coordinates are cross referenced with radio beacon signal data, if available to check accuracy. If none of that info is forthcoming, then the INS does the full laborious align calculation based on the Earth's rotational drift speed at the point on its surface which you are on, in combination with magnetic variation and a heading calculated from that. There's not much you can do about the rotation aspect of it, since you can't speed up the Earth, but the magnetic variation calculations can eliminate some magnetic anomaly possibilities caused by some locations on Earth, if they are able to have a bit of a clue as to a a starting point, based on radio triangulation.

A more interesting one with regard to radios tweaking the INS/IRS position, occurs at the point where you go on the runway and line up for take off. When you hit TOGA and the throttles move, this sends an updated position to the aeroplane's nav systems based on how far you are from the ILS signal transmitters. This is very accurate information indeed because you are typically dead centre of the concrete right near the piano keys and on a very specific known magnetic heading, which updates as an INS drift correction.

Interesting and informative info -- thanks.

Al

[SAS443 1,728]

40 minutes ago, Chock said:

During alignment, the input fields on the INS equipment flash, and the PFD flashes as well on some aeroplanes, this is to get you to remind you to put in the gate/stand coordinates to help speed up the alignment process

It needs present position in order to complete the alignment cycle, It is not a means of speeding things up, merely just a step to complete the whole cycle 🙂 

The INS will make a sober cross check with entered latitude (INS can never calculate longitude)  against the INS' own estimated aircraft latitude. For some installations (the Litton 92 for example) they must agree within 30nm for the alignment process to proceed, else you will get flashing warning "ENTER PPOS" and "ALIGN FAIL".

40 minutes ago, Chock said:

A more interesting one with regard to radios tweaking the INS/IRS position, occurs at the point where you go on the runway and line up for take off. When you hit TOGA and the throttles move, this sends an updated position to the aeroplane's nav systems based on how far you are from the ILS signal transmitters. This is very accurate information indeed because you are typically dead centre of the concrete right near the piano keys and on a very specific known magnetic heading, which updates as an INS drift correction.

Earlier 737 models w/o GPS, the FMC POS would update to be equal to runway  LAT/LON position (actually landing threshold of the departure runway) when you push TOGA. Nowadays if the FMC has GPS update this feature is inhibited.

Edited August 30, 2020 by SAS443

[FlyingInACessna 656]

1 hour ago, bonchie said:

I really don’t care enough.

Ok.....?

[jon b 2,050]

2 hours ago, SAS443 said:

Earlier 737 models w/o GPS, the FMC POS would update to be equal to runway  LAT/LON position (actually landing threshold of the departure runway) when you push TOGA. Nowadays if the FMC has GPS update this feature is inhibited.

Yep, don’t know about the 737 but the 747 gave you the option to enter a displacement figure in meters in case you made a departure from an intersection.

I heard a story of one guy in the old days (90s) somehow  mistakenly enter EGKK instead of EGLL out of habit in the POS INIT page and make it all the way to ocean entry west of  Scotland before the mistake was spotted and they had to turn round and come back to realign the IRS as they couldn’t make the crossing.

[PTI139 135]

19 hours ago, FPStewy said:

You can some sort of way do it in the G1000 or G530 just select the nearest VOR you'll see all distances to VOR's even the low ones. It just ain't right 😞

Yes, I considered that either 🙂

But this workaround only works if the desired VOR is on the first page of the „Nearest“ page.

But better than nothing...