Intercepting the ILS course

[tflash]

There is something I didn't quite understand in FSX, and I see I have the same problem in DCS.

 

I have no problem with TACAN or ILS nav, to get the signals, indications on ADI and HSI etc. But I always get to the airfield quite off the mark, not aligned with the runway. In essence, when I have visual of the runway, I correct my course untill I am roughly aligned with it a few miles out and then indeed my ILS thingy works and guides me perfectly to touchdown.

 

The HUD waypoint indicator goes to the center of the runway, and so is not helpfull at all to align with the runway axis from far out.

 

In FSX, I see the runways lights from far and so I turn around the airfield untill I see that I am aligned with the right runway, see the green lights and land perfectly on ILS.

 

But how do you do this all in zero visibility conditions? Are you guys turning around the airfield until you get the right bar alignment in the ADI from the ILS? Or do you get a heading from the tower that flies you to an intercept point? I have the impression the heading from the tower just is at the center, not a standoff point ideally suited to start the landing?

 

I dunno if you understand my problem? I would think you need a point a few miles out BEFORE the runway from which to start the descent?

[Quig]

While not being an expert at all, there are a couple of things to aid you with your alignment.

 

Firstly, when you contact the ATC you get directions to a point roughly 10nm off the runway, you'll easily notice this if you put a steerpoint on the airfield of you choice, and then talk to ATC, they'll give you a heading and a distance which do not match that of the airfield itself. This point is lengthwise out from the runway.

 

Secondly, at the same contact call they give you which runway to land at. You can then dial in that course on the HSI, and it will give you the indication when you're aimed in the runways direction, and when you're aligned with it.

Worth noting is that this needle isn't perfect, it oftentimes puts itself slightly off to the side when you're aligned perfectly for the runway, but if you get that far, you're regular ILS steering bars should be up and running, and you can ignore the HSI indicator from then on out.

[JesseJames38]

Call into the airport for inbound. The airport will tell you to fly XXX heading for XX miles. and land on runway XX. for the example we will use the heading 144. for 25 miles. with the runway of 12. (runway 12 would be around 120 for the runway heading) At this point you will want to steer your aircraft on heading 144, at this time i would set the auto pilot on. Then i would go to the HSI and set the coruse knob to headding 120, I would select the airport by the divert page so i can get the waypoint to pop up on the hud for the airfield. when the Course Deviation Indicator starsts to move to line up with the HSI courise arrow i will start to turn into the coruse heading. When the course deviation indicator lines up with the course arrow you should be heading in like with the runway, then be able to line up on the locolizer and glideslope on the ADI

 

i am sure some one else will come along and make it less confusing then what i have said.

 

Jesse

[tflash]

He guys, I think that that sums up what I was missing: I was in the dark about the heading / miles and runway indications I got from the tower.

 

Many thanks, I'll be trying this right away!

[LawnDart]

To piggyback on what slackerD said...

 

Most real life intercepts are ~30 degrees +/- 10 depending on how far from the course the final vector is.

 

Plan to join the localizer outside the outer marker (or final approach fix), usually ~5 nm from the touchdown zone. Most intercepts occur between 5-10 miles from the field (in some cases as far out as 25 miles).

 

The 300 feet per NM rule of thumb also works to fly a visual approach. If you're 5nm from the field, you should be at ~1,500 feet AGL (5 x 300). If you're 2 miles from the threshold you should be at ~600 feel AGL, etc. You'd then apply the field elev to your barometric readout. So, if the field is at 180 feet MSL, you should be indicating 1,680 feet MSL at 5 nm ((5 x 300) + 180), and 780 feet MSL at 2 nm ((2 x 300) + 180). It also helps to keep this mental math in mind even in IMC conditions, knowing where you are (good situational awareness) and roughly how high you should be at a given distance from the airport. In the real world ATC might leave you high and dry from time to time (yes they make mistakes, too), and you may need to remind them about "lower" or you will be the one unable to intercept and configure your aircraft for final approach.

[BluesmanSF]

In the real world ATC might leave you high and dry from time to time (yes they make mistakes, too)

 

No, we don't. ;)

 

But yeah, those are indeed good points.

Edited July 31, 2011 by BluesmanSF

[LawnDart]

No, we don't. ;)

 

It's always the same places and same controllers, too. :music_whistling:

[Jimmah]

You could use the TACAN to make up your own approach with a procedure turn. Fly directly to the airfield/TACAN, and once overhead fly outbound on the reciprocal of the runway heading (e.g if runway heading is 094, fly 274) for 10-12 miles. Then, when it's time to turn back, start with a 45 degree turn (lets say left), and hold that new heading for a minute. At the end of the minute turn 180 degrees back in the opposite direction (e.g. right). Once you've rolled out you'll find yourself approaching the extended centreline, ready to make a further 45 degree turn onto a 10-12 mile final (at which stage you can switch to the ILS & fly that).

 

It's not as complicated as it sounds. See below.

 

 

Also, it's worth looking at the airport charts on the DCS wiki to get the correct runway heading. If you dial in 120 on your ILS for runway 12, but the runway heading is in fact 124, you'll find yourself a fair way off the centreline. Fine if you can see the runway from 2000', not so fine when you break visual at 200' & find yourself having to do some last minute manoeuvring.

[Jimmah]

No, we don't. ;)

 

Quite right :thumbup:

[tflash]

Thanks for the info! Not only can I now land perfectly on diversion airfields, but I think my understanding of the basics has improved dramatically!

 

I finally know things about the HSI that I should have known ages ago, and never quite really grasped.

[Jimmah]

ILS reads raw beam position no matter what your CRS setting. It doesn't work like a TACAN. It's usually helpful to rotate the HSI picture with the CRS knob so the direction to runway is right.

 

Oops, you're quite right. An incorrect course selection does invariably leads to drunken looking centreline tracking though, or the feeling that there's some badass winds about.

 

On the subject, I'm surprised the HUD doesn't feature some kind of flight director for approaches. I'm guessing the A-10 isn't generally used in IMC.

[PoleCat]

Very informative thread. Thanks for the detailed explanation.

 

Out

[LawnDart]

Typically partial panel would be the loss of one or several gyroscopic instruments (e.g. attitude indicator and heading indicator), requiring you to fly the approach using just the needles, turn coordinator, mag compass etc.

 

The other scenario would be the loss of the pitot-static system. Frozen altimeter and/or airspeed indicator or airspeed indicator reading zero, or decreasing as you decend (trapped pressure being less than the outside pressure). This isn't typically practiced during partial panel precision (ILS) and non-precision (VOR, GPS) approaches, since the loss of gyroscopic instruments affect your ability to steer and control your path much more on an approach.

 

Try failing the ATT IND, HSI and backup gyroscopic instruments. Then load up a mission with IMC weather conditions and/or night and try it!

 

Making timed turns and compass turns takes practice and discipline!

[Fish]

Summary:

1. Intercept at a manageable angle, about 15°

2. Plan to intercept at ~9nm / 2,500'. The closer the join, the lower you have to be.

2. Join the localizer first and then the glide scope second. Don't do both at the same time.

3. Intercept the glide scope from below with level flight.

4. Plan 318' per NM for a 3° scope

 

Remember, set your altimeter to the correct QNH setting for the atmosphere! Know your runway elevation!

 

5. Get your aircraft configured early, gear speed, aoa, flaps, so when you pick up the GS, you have little else to concentrate on. (well outside 5 miles).

 

 

 

[/Quote]

PROCEDURE TURN !

Unless this is prescribed in the approach plate, there are easier (and quicker) ways !! For example

 

..........If you dial in 120 on your ILS for runway......

 

I'm sure you meant 'on your course setting knob'...

Edited July 31, 2011 by Fish

[xgibbousx]

I've just posted my own approach and landing technique as a training video in the following thread:

 

http://forums.eagle.ru/showthread.php?t=77812

 

Hope this helps.

[Jimmah]

I'm sure you meant 'on your course setting knob'...

 

I thought it was "pointymebob"?

[Fish]

I thought it was "pointymebob"?

 

U gotta remember that you have to 'dial' a frequency into the ILS, and some folk could b confused.

 

:thumbup:

[Maxpilot]

First the yellow command steering bars on the ADI don't work as they are supposed to. Either you have to know and adapt to how they mis-function or simply stow them.

 

May I ask you to elaborate this a little bit? What is wrong? And how to handle it?

 

Regards

 

Max

[effte]

May I ask you to elaborate this a little bit? What is wrong? And how to handle it?

 

Currently they are showing your deviation from the glide path and localizer centerline of the ILS, acting as a repeater of the real localizer course deviation (CDI) indicator on the HSI (main needle center part) and GP CDI caret on the lefthand side of the attitude indicator.

 

They should be giving you steering commands, i e tell you if you need to pitch up or down and bank more or less to intercept the ILS GP/LOC.

 

Leave'em stowed for now and fly using the proper CDIs.

 

Cheers,

Fred

[WildBillKelsoe]

While not being an expert at all, there are a couple of things to aid you with your alignment.

 

Firstly, when you contact the ATC you get directions to a point roughly 10nm off the runway, you'll easily notice this if you put a steerpoint on the airfield of you choice, and then talk to ATC, they'll give you a heading and a distance which do not match that of the airfield itself. This point is lengthwise out from the runway.

 

Secondly, at the same contact call they give you which runway to land at. You can then dial in that course on the HSI, and it will give you the indication when you're aimed in the runways direction, and when you're aligned with it.

Worth noting is that this needle isn't perfect, it oftentimes puts itself slightly off to the side when you're aligned perfectly for the runway, but if you get that far, you're regular ILS steering bars should be up and running, and you can ignore the HSI indicator from then on out.

 

 

Why go through all that? he has an initial point, and a second point just ahead on the tarmac (takeoff point), use the hud as SOI, toggle to steerpoint zero, and it shoul be visible on the runway, use the slew function to place a SPI, and switch back to airfield waypoint. now all you have to do, is to place both points behind each other. That is the alignment you need. If you dont understand, let me know so I post a track.

[Wolf Rider]

Currently they are showing your deviation from the glide path and localizer centerline of the ILS, acting as a repeater of the real localizer course deviation (CDI) indicator on the HSI (main needle center part) and GP CDI caret on the lefthand side of the attitude indicator.

 

They should be giving you steering commands, i e tell you if you need to pitch up or down and bank more or less to intercept the ILS GP/LOC.

 

Leave'em stowed for now and fly using the proper CDIs.

 

Cheers,

Fred

 

 

never been in a real cockpit, so I don't know... but what the yellow horizontal needle seems to do, is to give early advice of variation.

 

ie if low, and power on is applied to climb to "get onslope" the needle will rise way before the carat does, enabling the pilot to power down a bit and help prevent going too high and finding himself in a position of then "chasing the needle"

alternatively... being onslope and if beginning to vary off slope, the needle gives a clearer indication, before the carat can be seen to move.

the needle seems to be counting in ones, so to speak and the carat counts in tens

 

is this what you mean by "repeat"?

Edited August 3, 2011 by Wolf Rider

[Phuz]

Now here's the fun part: Partial panel. Fly the ILS without attitude or altitude indicators. You can't get the instrument rating without demonstrating the ability to do this to standard.

 

This (and other tasks of course) is what makes the instrument rating the most difficult thing in aviation to achieve.

 

Meh, imo the most difficult thing in aviation is getting a job that pays well.

[Maxpilot]

Thanks a lot to all for sharing great knowledge here. Much appreciated!

 

Regards

 

Max

[Maxpilot]

Ups - I'm missing the Posts of slackerD here? What happened?

[Elwin]

Apparently, user slackerD doesn't exist anymore in Member list.