Flightradar 24 and Marine spotting odds and sods.

On
But how does it keep the aircraft on the centerline? Bit of crosswind, or slightly more efficient brakes on one side, or even tyre pressures could see it off the side. How does it correct the nose wheel(s)?

Well aware of the temps in DXB/RUH/JED etc. Like a hairdryer to the face walking outside!
Only know the details of autoland the 744 and the 777.

In both those aircraft pretty much at touchdown the autoland system would transition into a rollout mode and the aircraft would start using lateral guidance from the ILS localiser (the left/right signaling bit of the ILS system) to sense any deviation from the centerline. It would then demand appropriate rudder and nose wheel steering inputs as required to stay in the middle….so often as not you’d end up thumping along the centre lines lights.

On a really crappy day you’d leave the the autopilot in with the auto brakes handling the decel right down to taxi speed…and the you’d have to grope your way to the terminal….
 
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On

Only know the details of autoland the 744 and the 777.

In both those aircraft pretty much at touchdown the autoland system would transition into a rollout mode and the aircraft would start using lateral guidance from the ILS localiser (the left/right signaling bit of the ILS system) to sense any deviation from the centerline. It would then demand appropriate rudder and nose wheel steering inputs as required to stay in the middle….so often as not you’d end up thumping along the centre lines lights.

On a really crappy day you’d leave the the autopilot in with the auto brakes handling the decel right down to taxi speed…and the you’d have to grope your way to the terminal….

Thanks - so back to Toastie's take-off in fog scenario, I wonder if the same ILS setup could be used to keep the thing in a straight line in a pea-souper? Seems to be the same requirement - keep the nose aiming along the centerline.

As for bumping along the lights, I wonder why they didn't just offset it a foot to the left or right? Would save wear and tear on the landing gear and the lights themselves. I certainly recognise the sensation of landing like you were on a rumble strip at the side of a motorway!
 
As per @Nicky swango for the landing. CAT 3A gives you guidance down to touchdown, 3B gives you guidance after touchdown. Decision altitudes are 50’/0’ respectively but it’s the visibility that governs whether you can attempt it or not.

Re the take off, the normal lowest minima for take off is 125m but could well be higher depending on aircraft kit, crew qualifications and runway lighting etc. You can do this without the runway being ILS equipped so the only lateral guidance you’ve got is the runway centreline lights hence why the lighting has to be of a minimum standard.

The 787 can come down to 75m but requires additional criteria to be met. One is that the runway must be ILS equipped and serviceable. The reason the 787 can do it and most (all?) other big jets can’t is it has a HUD so simultaneously monitoring outside and instruments is possible. It also has a very sensitive readout of ILS Localiser readings on the HUD. My avatar is the view through the HUD; you can see outside and instrumentation at the same time.
 

Ritch

LE
Thanks - so back to Toastie's take-off in fog scenario, I wonder if the same ILS setup could be used to keep the thing in a straight line in a pea-souper? Seems to be the same requirement - keep the nose aiming along the centerline.

As for bumping along the lights, I wonder why they didn't just offset it a foot to the left or right? Would save wear and tear on the landing gear and the lights themselves. I certainly recognise the sensation of landing like you were on a rumble strip at the side of a motorway!

If I remember right, It wouldn't work for take off as the ILS stands for Instrument Landing System and is used at the end of a runway that the aircraft is landing on to guide them in.

I could be spouting complete böllocks as usual.
 
If I remember right, It wouldn't work for take off as the ILS stands for Instrument Landing System and is used at the end of a runway that the aircraft is landing on to guide them in.

I could be spouting complete böllocks as usual.

Sounds like exactly what's required... why can't the same (or similar) system be used to guide them out?
 
If I remember right, It wouldn't work for take off as the ILS stands for Instrument Landing System and is used at the end of a runway that the aircraft is landing on to guide them in.

I could be spouting complete böllocks as usual.
On most civvie installations the localiser aerials are at the far end of the runway you landing on/departing from, so the signal should be very much available for left/right guidance on the take-off roll, though whether it‘s legit/allowable/and limitations on use varies according to the sort of factors Toastie has mentioned.

My brain cells are rapidly fading on this stuff but I do remember we didn’t have a HUD :confused::confused:

OTOH on the most (?all) of the 744s I flew and some of the 777s we had a thing called a Paravisual Display (PVD) which was a indicator that sat just within your line of sight on the glareshield and if tuned in/set up properly with respect to the localiser gave you a some form of left/right indication as you blasted down the runway…

I think on the 777 using the PVD allowed you to go in 75 meters (RVR)…

interestingly (or not) the later airframes we bought didn’t have PVDs. The reason for that was that they were so rarely used in anger that management considered that the cost of maintaining them wasn’t worth the benefit of having the reduced limits..
 

Ritch

LE
On most civvie installations the localiser aerials are at the far end of the runway you landing on/departing from, so the signal should be very much available for left/right guidance on the take-off roll, though whether it‘s legit/allowable/and limitations on use varies according to the sort of factors Toastie has mentioned.

My brain cells are rapidly fading on this stuff but I do remember we didn’t have a HUD :confused::confused:

OTOH on the most (?all) of the 744s I flew and some of the 777s we had a thing called a Paravisual Display (PVD) which was a indicator that sat just within your line of sight on the glareshield and if tuned in/set up properly with respect to the localiser gave you a some form of left/right indication as you blasted down the runway…

I think on the 777 using the PVD allowed you to go in 75 meters (RVR)…

interestingly (or not) the later airframes we bought didn’t have PVDs. The reason for that was that they were so rarely used in anger that management considered that the cost of maintaining them wasn’t worth the benefit of having the reduced limits..

Ahh okay, everyday is a schoolday! I knew the localiser was at the end of the runway, guiding the landing plane in. Had no idea it *might* be possible to use it to take off.
 

BlipDriver

War Hero
As with so many things in air traffic, GPS is making inroads in this area. Although mainly used for improving the accuracy of approaches to the airport through Precision-Area Navigation (PRNAV), it has also been used to provide an alternative to ILS. At the moment it is only in use as an equivalent to CAT1, but work is ongoing on Ground-Based Augmentation Systems. GNSS augmentation - Wikipedia

This sort of system would have applications for departures, but I guess the concept of accelerating into blankness would be the hardest obstacle...
 
As with so many things in air traffic, GPS is making inroads in this area. Although mainly used for improving the accuracy of approaches to the airport through Precision-Area Navigation (PRNAV), it has also been used to provide an alternative to ILS. At the moment it is only in use as an equivalent to CAT1, but work is ongoing on Ground-Based Augmentation Systems. GNSS augmentation - Wikipedia

This sort of system would have applications for departures, but I guess the concept of accelerating into blankness would be the hardest obstacle...
I love the GBAS concept and the potential to have a single system covering every runway. Unfortunately it's not great at middle Eastern airports or those near the equator due to signal propagation. Not sure what current progress is but best performance a couple of years ago was CAT 1.
 
It’s still classed as a Non Precision Approach with correspondingly high minima relative to ILS. The really big advantage is that it can be used to construct curved approaches (the original intention behind the now almost wholly defunct MLS). This means you can put “instrument” approaches in where you couldn’t before as ILS, VOR, NDB etc only goes in a straight line and if there was terrain in the way, it was a non starter.

Another huge advantage is that it requires no ground equipment so makes installing an approach in parts of the world where it would have previously been prohibitively expensive is now just a question of drawing a 3D approach and publishing it. The cost is placed on the operator as all the kit is either on the satellite, which is there anyway, or on the aircraft. Integrated Approach Navigation, IAN, is now pretty standard fit. On the 787 all Approaches are Armed and Selected using a single button marked APP. The kit then configures based on what approach you’ve selected in the FMC (nav computer).

Here’s the newly minted approach onto 29 at Dubrovnik. Previously there was no instrument approach because the terrain to the southeast precluded it:

3423ECBF-4FEB-4C6A-82FD-814E69A9BE48.jpeg
 
Low viz takeoff in the helo world - when I were a lad.

Minimum viz/RVR for departure was 150m but bear in mind that it was done from the hover so you were in flight the whole time.

Accelerate to SE safety speed while maintaining visual contact with the white line in case a donk stopped then climb out. Some guys would tune in the ILS but the localiser could just swing from side to side as it was at the “wrong” end. Most guys just engaged HDG hold. Not a lot of wind in foggy conditions- stand fast RNAS Culdrose!

TBH in 25 years on the North Sea I probably did one or two low
viz departures in anger and none of those right down on the limit.
 

BlipDriver

War Hero
It’s still classed as a Non Precision Approach with correspondingly high minima relative to ILS. The really big advantage is that it can be used to construct curved approaches (the original intention behind the now almost wholly defunct MLS). This means you can put “instrument” approaches in where you couldn’t before as ILS, VOR, NDB etc only goes in a straight line and if there was terrain in the way, it was a non starter.

Another huge advantage is that it requires no ground equipment so makes installing an approach in parts of the world where it would have previously been prohibitively expensive is now just a question of drawing a 3D approach and publishing it. The cost is placed on the operator as all the kit is either on the satellite, which is there anyway, or on the aircraft. Integrated Approach Navigation, IAN, is now pretty standard fit. On the 787 all Approaches are Armed and Selected using a single button marked APP. The kit then configures based on what approach you’ve selected in the FMC (nav computer).

Here’s the newly minted approach onto 29 at Dubrovnik. Previously there was no instrument approach because the terrain to the southeast precluded it:

View attachment 616582
From my link, it's mostly used as an ILS alternative to CAT1 (200ft decision height) with some that use additional resources able to operate CAT2 (100ft), CAT3 is "waiting for compatible airliners".
Specifically in relation to @Ritch 's question, could such a system be used to aid departures in low-viz conditions?
 
From my link, it's mostly used as an ILS alternative to CAT1 (200ft decision height) with some that use additional resources able to operate CAT2 (100ft), CAT3 is "waiting for compatible airliners".
Specifically in relation to @Ritch 's question, could such a system be used to aid departures in low-viz conditions?
No, it’s not (yet) considered accurate enough. I’ve not seen or heard of it being used below Non Precision minima for approach or at all for LVP departures. The departure case has been happening down to 125m for years and the 75m case is a HUD / ILS combo anyway so RNAV doesn’t come into it. Could you post the link for my education please?

It is however used extensively for RNAV SIDs and STARs (and of course en route which is now almost exclusively RNAV).
 

BlipDriver

War Hero
No, it’s not (yet) considered accurate enough. I’ve not seen or heard of it being used below Non Precision minima for approach or at all for LVP departures. The departure case has been happening down to 125m for years and the 75m case is a HUD / ILS combo anyway so RNAV doesn’t come into it. Could you post the link for my education please?

It is however used extensively for RNAV SIDs and STARs (and of course en route which is now almost exclusively RNAV).
Used more extensively Stateside for airports that haven't got ILS according to the Wikipedia link:
(I'm using GPS as a shorthand for all satellite based navigation systems)

In en-route we had specific "attention getters" on the TDB to advise us of the RNAV status of any particular flight as this could affect how it was handled.
 

Ritch

LE
Just had this fly over as I was in the yard putting the bins away. Looked like the ramp was down and had legs dangling off the edge. I wouldn't fancy that - it's brass monkey's up here.

Screenshot_20211122-125514_Flightradar24.jpg
 
Don't you just love management? The sort who think that the bus with wings can easily pull over and wait.
The only thing rising in anyone around Luton is their blood pressure, their lunch and their desperate desire to be somewhere else.
 

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