Using mark point with ILS.

[metalnwood]

I am on holiday reading a book called 'viper pilot' and as you. Can guess it has an f16 as the main aircraft.

 

There is one part where the pilot is describing having to bring down 10 f16's in 1/2 mile visibility and quoting the book he says

 

-------_-

 

,I'd fly us down to the end of the runway using gps guidance and take a MARK point, a precise latitude and longitude for whatever piece of ground I chose. It could then be coupled with the aircrafts instrument landing system and would generate horizontal and vertical steering to that point in the ground.

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Of course this is not in an a10 but being away on holiday I can't check e manuals etc.

 

I haven't heard of it being possible but wondered if it was?

[The LT]

The A-10 CDU has a possibility of adding mark points and they can be used as navigational aids if that's what you're asking. :)

[Habu_69]

In DCSW A-10C the pilot can make a mark point at the runway end using HUD or TGP as SOI, which would provide a glideslope cue. Course steering, however, would have to be set in the HSI, I think.

[Wayc00lio]

Make a mark point and you can use it just like any other nav point.

[Rongor]

This is indeed a way to approach a runway. But of course it is not an instrument approach. The ILS information guides the aircraft along a published mandatory glideslope. This may of course not play a role within DCS. If you don't like to use the ILS, you can reach the runway with your markpoint.

As far as I understand the book quote, the narrator used the ILS but didnt know the approach path direction. Therfor he overflew the runway end to set a markpoint before proceeding to ILS establishment.

[metalnwood]

I know about using it as a nav aid but this was a little different.

 

The airport was not equipped with ILS capabilities but there was a known runway direction and the flight leader needed to safely bring down 10 f16's in less than 1/2 mile visibility.

 

He needed to bring them down in an orderly pattern to ensure there were no accidents etc.

 

After he made the MARK point he sent the coordinates to the others. Now, they didn't use this on their hud for their approach. Somehow the f16 had the capability to to use mark point and simulate the guideslope using the ILS instrumentation on the f16.

 

I.e. the pitch steering bar and the glide slope deviation scale and glide slope indicator came in to life and worked as if the airport was equipped with ILS.

[Home Fries]

With no ILS cueing and 1/2 mile visibility, the mark point cues the pilots to the threshold of the runway. Combined with a known heading which is input into the HSI, you can fly AoA using the donut lights and putting the FPM just above the mark point to estimate glideslope, which will at least get you lined up within visual range of the runway threshold. From there, it's a visual landing. It was less of an ILS approach and more of an improvised NDB without the beacon.

 

Certainly not easy, but they knew that there were no obstructions in the way, which is normally the biggest danger in low visibility non precision approaches.

Edited January 12, 2013 by Home Fries

[metalnwood]

Home fries, I understand what you are saying but you should take me for my word that what I am saying is the procedure they performed.

 

I know what to do in the a10 as you describe but the question was is it possible to do in the a10 what they did in the f16.

 

To quote another paragraph -

 

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At about eight miles the ILS symbology fluttered and began its slow drop. This was the guide slope, the controlled decent, that I had to maintain to the runway. The other bar, a vertical one, would keepme lined up on the runway

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So it appears that at an airport that doesn't support ILS he set a mark point, about 1/2 mile down e threshold of the strip and told the f16 to give him ILS guidance based off that information.

Edited January 12, 2013 by metalnwood

[Kaiza]

Hey mate, havent tried it, but as I understand it is possible using VNAV on the CDU. Check out these threads, second link includes a tutorial:

 

http://forums.eagle.ru/showthread.php?t=63418&highlight=VNAV

 

http://forums.eagle.ru/showthread.php?t=73222&highlight=VNAV

 

I would say that this procedure would only be used in a "last resort" scenario. As you can imagine there would be plenty of scope to smack into terrain flying a non certified approach with no obstacle clearance calculations done etc. If the coast is near by, a let down over water is another option (ie slow descent using the radalt until visual, then nav in at low level visually).

 

Many modern CDUs will allow you to construct complete approaches including arcs, teardrops, holds etc. This feature can be quite useful landing at places with moving or changing runways/terrain such as antartica etc. Wherever possible the approach will be constructed on the ground and then saved in the CDU prior to flight.

Edited January 12, 2013 by Kaiza

[metalnwood]

Kaiza, that appears to be the functionality. Lots of things to forget about if you are not using them :)

[Kaiza]

Food for thought on F-16 vs A-10 flying this type of approach:

 

-The F-16 has a RADAR, so even though the approach has been built down an area of unknown obstacles, the pilot will have a plot of surrounding terrain. The pilot can take a ground mapping SAR image and freeze it for the approach providing a map of surrounding terrain for additional situational awareness. Something you obviously wouldn't have in an A-10!

 

-When flying a random self built approach like this, the missed approach sequence would have to be taken into account as well, in case you are unable to gain visual reference with the runway. In places like Batumi this can be a bit of a headache as there is a lot of steep rising terrain about. In an F-16, this is no problem at all as you can almost climb vertically, in an A-10 you don't have this luxury and would have to put a lot more consideration into your missed approach options.

 

Hopefully the airfield you are landing at has some kind of approach already charted, ie a VOR/DME. If this is the case I would make my markpoint from the L/L of the NAVAID (off the approach chart) and then fly the charted apporach. This way you have guaranteed obstacle clearance for the approach and missed approach.

 

On a separate note, seems strange that this guy had to overfly the runway to make his markpoint? How exactly did he get down to do that? I would have thought he would just spot SAR the runway and create a markpoint 1000' in from the threshold off his RADAR SAR image.

Edited January 12, 2013 by Kaiza

[Home Fries]

Home fries, I understand what you are saying but you should take me for my word that what I am saying is the procedure they performed.

 

I know what to do in the a10 as you describe but the question was is it possible to do in the a10 what they did in the f16.

 

To quote another paragraph -

 

-------

At about eight miles the ILS symbology fluttered and began its slow drop. This was the guide slope, the controlled decent, that I had to maintain to the runway. The other bar, a vertical one, would keepme lined up on the runway

----------

 

So it appears that at an airport that doesn't support ILS he set a mark point, about 1/2 mile down e threshold of the strip and told the f16 to give him ILS guidance based off that information.

 

I read the book, and I was thinking about the F-16 (at least based on my "experience" with BMS), but I can't honestly remember if the field didn't have ILS, or if the WX was just well below minimums. At that point, a mark point would provide additional SA for the other pilots.

 

I honestly don't know for sure if the ILS needles can be slaved to a mark point in the F-16; I'll take another look at the book.

[metalnwood]

Correct Kaiza, many more things to think about if you were to use it. I was just curious if it was possible.

 

Home fries, there was no ils there and he states it works as I was describing, he also noted that its not as accurate ad the real thing but it clearly utilises the gsi etc.

[MatzWarhog]

Take off and gain altitude. Use the TGP (lasing) to set a Markpoint. Set that Markpoint as SPI. Since the pilot would know the runway's bearings, he could then set the HSI course setting indicator to the correct bearing for the runway. Have your EGI on and turn on the on the ILS (not the reciever, but on the NMSP) and unstow the course deviation needles, and then you can align with the runway without a deviated course to the approach. Set the CDU to "Steerpoint" and it will give you "Time To Go" and elevation of the Steerpoint, based on you current SPI... thus creating a crude ILS "signal" of sorts. Do this at the end of the runway, and you should be almost dead on... elevation, Time To Go, bearing and your alignment.

 

Matz

[metalnwood]

Thanks Matz. The hard ing about being on holiday with a bit of Internet is reading up on stuff you would want to try and then not being able to.

 

It's tough when the holiday starts to be a countdown for how many more days until you get back ;)

[ilikepie]

 

It's tough when the holiday starts to be a countdown for how many more days until you get back ;)

 

don't worry, i saved you a couple of cubic meters of top soil to move when you get back,

 

its the final countdown.......:thumbup:

[MatzWarhog]

Thanks Matz. The hard ing about being on holiday with a bit of Internet is reading up on stuff you would want to try and then not being able to.

 

It's tough when the holiday starts to be a countdown for how many more days until you get back ;)

 

I flew a quicky just to be sure, and everything above, will guide you in at the correct approach heading. I didn't, however, engage my landing gear to see if a AoA indexer would activate. I suspect that it would not, as it is relying on the ILS/Tacan Beacon (please correct me if I'm wrong on that one guys). But basically, yes, you can use just a markpoint to determine course deviation (as long as you know the runway bearing), and by using the steerpoint, you can gain the additional info not to slam into the ground... which I seem to do a bit of! :D

 

Matz

[MatzWarhog]

Very true... you could meet a truck passing by as well... but it would get you in the proximity.