Missed GPSRNAV Approach at YWOL

[bentleg]

I'm having an issue with KLN89B GPS. Would appreciate advice from someone who is expert.

When flying the RNAV (GNSS) RWY16 approach into YWOL and executing a missed approach after passing WOLNM, I press GOTO (WOLNH - missed approach holding point) and ENTER, then when between the missed approach point WOLNM and the missed approach holding point WOLNH the GPS flips back to the final destination YWOL rather than continuing to guide to the missed approach holding point WOLNH.

Is this normal http://static.pprune.org/images/smilies/confused.gif Am I doing something wrong?

[ForkTailedDrKiller]

Am I doing something wrong?

You sure as hell are!

You're not using a Garmin!

Dr :8

[alphacentauri]

Um maybe....firstly I am not familiar with the KLN89B GPS.

When you load the RNAV approach the GPS should recognise all of the available waypoints for that approach, including the missed approach holding point (WOLNH).I assume that you didn't have to press goto for all of the other waypoints? so why would you need to press it for the missed approach holding point? On the Garmin 430/530 at the missed approach point the GPS goes into a 'suspend' mode to allow the pilot to sort his/her s**t out, then the pilot must elect to continue with the missed approach. On the GARMIN 430/530 series this is done by pressing the OBS button. The gps then switches back into navigation mode and takes you to WOLNH

Is there a similar 'OBS' button on the KLN89B GPS?

My guess is that in order to load/activate the RNAV approach you had to either have been 'going to' YWOL or it was the last waypoint in your flight plan. When you hit the 'GOTO' button, the first thing it loads is the last place you were heading to, in this case YWOL.

Hope this helps

Alpha

[Matt-YSBK]

It doesnt matter what it says as long as you make a left turn. If you made a right turn then i guess we will not be seeing posts from you anymore :)

[bentleg]

When you load the RNAV approach the GPS should recognise all of the available waypoints for that approach, including the missed approach holding point (WOLNH).I assume that you didn't have to press goto for all of the other waypoints?

Correct on both points.


On the Garmin 430/530 at the missed approach point the GPS goes into a 'suspend' mode to allow the pilot to sort his/her s**t out, then the pilot must elect to continue with the missed approach


Yep the KLN89B also goes into a suspend mode etc. Having decided to continue with a missed approach the manual says press the GOTO button and the missed approach holding point (WOLNH) will be next in line, which it is. Then press enter to confirm and WOLNH come up as the next waypoint. However whilst en route to WOLNH it flips back to YWOL.

Is there a similar 'OBS' button on the KLN89B GPS?

Yes there is. It has occurred to me, yet to try it out, if I set the CDI to 036 (heading desired at WOLNH) and press OBS, after doing the GOTO bit, that might work, but the manual doesnt say to do that.

[bentleg]

It doesnt matter what it says as long as you make a left turn.


Yes, made a left turn

[Captain Nomad]

From experience with KLN90 series GPS' they can do some funny things occasionally. It has been recomended to me to enter the destination (eg YWOL) TWICE and then load the RNAV - this seems to produce trouble free transitions. :ok: Don't know if this will help you or not - try in VMC first!

[alphacentauri]

I have just flipped thru the KLN89B user guide, to find that you are correct.

In your case when you hit the 'GOTO' button at the missed approach point is the WOLNH point highlighted? or is YWOL?

I am guessing that the WOLNH waypoint is highlighted, or this would be a 'where did the WOLNH waypoint go?' thread. So after you confirm 'GOTO' WOLNH I am assuming it gives you track guidance to WOLNH, or does it flip across to YWOL straight away? If it does give you guidance to WOLNH, how long after this does it switch to YWOL?

Ever had any issues with this GPS on other RNAV approaches?

[ReverseFlight]

I never found KLN89B user friendly but in order to go to WOLNH, I believe you scroll to the FPL page and then press DTO. The single cursor in the middle will light up and you must then scroll into the other waypoints on your pre-programmed flightplan, and when the correct one appears (WOLNH in your case), press ENT. It should then automatically revert to the NAV page to take you there. To cancel an unwanted OBS mode, press OBS so that the screen reverts to NAV to take you to WOLNH.

Hope that helps.

[onthedials]

I have seen several instances of this problem on both KLN89B and KLN94. It can certainly be frustrating, especially in the rain and when you have other issues to consider.

You understand that the waypoint sequencing from WOLNM to WOLNH is not automatic and you are correctly doing a D--> to WOLNH, so you are way in front of most!

I think what you are seeing, as it appears to "strangely" go "back" to YWOL following the the D--> to WOLNH on the missed approach, is that the geometry of your position line to WOLNH and that to YWOL satisfies the KLN89B’s conditions for passage of WOLNH in LEG mode and causes it to automatically sequence to YWOL, which will be the last waypoint in your flight plan assuming it ends at Wollongong. This will happen even before you thought you had reached WOLNH if the geometry is right.

This is particularly likely if you flew the approach in a reasonable north-westerly and have got to the south-east of WOLNH faster than you realised. Allowing for a bit of wind, and some work to get on the missed approach, the courses outbound to WOLNH and then from there back to YWOL are not very far apart, although in completely opposite directions. The KLN 89B "thinks" you have passed WOLNH long before you think that way, and because sequencing in LEG mode is automatic, it replaces WOLNH as the active waypoint with YWOL, but before you consider that you ever really reached or passed WOLNH.

You can avoid the problem by selecting OBS mode once you have D--> selected and are established on track to WOLNH, and then, having reached it (or very close), reverting back to LEG mode and, (only if necessary), doing a D--> to YWOL as required. However, if you use this solution, make sure you remember to go back to LEG mode, otherwise you might easily fly right past WOLNH and way out to sea… and then there might be all sorts of other problems!

Hope this helps.

OTD.

[barleyhi]

Correct "onthedials",
The other way would be to remove YWOL from the flight plan, after loading the approach in the KLN89B prior to commencing the approach.
Cheers

[rioncentu]

I am with Barleyhi

I have a KLN90B. If I load the approach into the flight plan (planning VOR to VOR), it will load the approach but the VOR remains in there.

That causes issues so I then have to delete the VOR from the flightplan after the approach has loaded.

I suspect your airport idetifier is still in the flight plan. Get rid of it and I think it will be fine.

[bentleg]

In your case when you hit the 'GOTO' button at the missed approach point is the WOLNH point highlighted? or is YWOL?

Yes, WOLNH is highlighted.

So after you confirm 'GOTO' WOLNH I am assuming it gives you track guidance to WOLNH, or does it flip across to YWOL straight away? If it does give you guidance to WOLNH, how long after this does it switch to YWOL?


It gives track guidance to WOLNH initially, but after a while, and well before WOLNH, it flips to YWOL. I cant be specific on the length of time as I have been preoccupied with other things.


Ever had any issues with this GPS on other RNAV approaches?



I have not done any other RNAV approaches.

[alphacentauri]

"onthedials" may have hit the nail on the head.

The WOLNH waypoint is coded in a GPS as a 'flyby waypoint and not a 'flyover' waypoint. When the gps senses that a waypoint is approaching, it calculates a distance to turn anticipation. When the tracks are the same but in opposite directions the distance to turn anticipation is infinite. The out bound track to WOLNH will be very close to the inbound track back to YWOL and so the distance to turn anticipation will be quite large.

So the scenario is this.....

You get to the missed approach point and decide to continue missed approach. You then press 'GOTO' WOLNH. The system sends you off in the direction of WOLNH, but also calculates a turn at WOLNH to go back to YWOL. Lets say distance from missed approach point to WOLNH is about 6nm. Turn anticipation for a reciprocal course may be about 4-5 miles. You are still tracking to WOLNH, then about 4-5 to run to WOLNH you pass the turn anticipation point and because inbound and outbound tracks are so close together you also pass the midpoint of the turn. This forces to system to assume you made the turn, and 'flewby' the WOLNH waypoint, thus sending you back to YWOL.

If you remove YWOL as the last flightplan waypoint, or pick some other waypoint....you shouldn't have a problem.

This is the problem with different GPS receivers. The GPS coding specification doesn't define what to do if the turn at a waypoint is greater than 120degrees. So each manufacturer can code their recievers differently. It would appear BENDIX/KING recievers always calculate a turn anticipation distance. I think in the same scenario GARMIN recievers would make you fly a course reversal at WOLNH, thus eliminating this problem. I have flown this approach with a GARMIN 430/530 and not had any problems.

Alpha

[AerocatS2A]

On the KLN89B are you able to insert a "gap" or similar that prevents waypoint sequencing at the end of the missed approach?

[always inverted]

We use the kln-90b in the 1900 and it is definately not a Garmin unit.
Our SOP's state for us to select the next waypoint, allbeit a hold or a fly over waypoint in the hilighted field in fpl0 or on the super nav 5 page so that when you commence the mapp, ie: climb and start the turn- if required then you can go direct to/ goto, (however you want to say it) the next waypoint in the missed approach as the kln90b does not provide waypoint sequencing onto the mapp.
Once you have done that then you have an active waypoint so selecting obs mode will allow you to set the correct course to be flown on the mapp.

Having it hilighted makes the process easier to follow when you are low to the ground and in the murk...

[always inverted]

The reason that it keeps defaulting to the destination is because there is no waypoint sequencing on the mapp, but once you have selected the first waypoint in the mapp then it will sequence you thru subsequent points, if there are any, to the end of the mapp which after the hold(if not in obs) will be to the destination, again.
Hope that helps. It should be the same over there as it is here, god knows we do enough of the bloody things.

[always inverted]

If the particular mapp requires a turn to the left, delay going direct to the next waypoint untill you have started the turn. The previous crap about the reciprocal and 5-6 nm intercept is irrelevant as THERE IS NO WAYPOINT SEQUENCE ON THE MAPP ON THE KLN90B...

[alphacentauri]

THERE IS NO WAYPOINT SEQUENCE ON THE MAPP ON THE KLN90B

I disagree. The missed approach holding point IS sequenced after the missed approach point. The fact that the GPS doesn't load it automatically does not mean it is not sequenced. The sequence is suspended until YOU decide that you want to go to the missed approach holding point, then after pressing OBS/GOTO (depending on your make of unit) the sequence is continued.

Likewise after reaching the missed approach holding point the next waypoint in the sequence would appear to be the destination (YWOL).

[desmotronic]

Agree the KLN series are no where near as user friendly as Garmin.

Bentleg sounds to me like the receiver is indeed providing you turn anticipation to the destination prior to you reaching the holding point.

Remember if a plan is active ie FPL#0 and you choose direct to a point in that plan the the receiver will automatically sequence as per FPL#0 after reaching the direct to waypoint or the anticipated turn point.

You can disable turn anticipation if desired FPL page 4 i think, or remove the destination from the end of FPL#0.

It has occurred to me, yet to try it out, if I set the CDI to 036 (heading desired at WOLNH) and press OBS, after doing the GOTO bit, that might work, but the manual doesnt say to do that.

Agree this should also work.

Ever had any issues with this GPS on other RNAV approaches?

Yes the KLN89 will not allow you make a reversal at an IAF, only at the FAF... eg if you try to load your approach when approaching IAF from the south the KLN will skip the IAF and go straight to the FAF. I believe the manual doesnt explicitly say it will do this but it does say reversals are only available at the FAF. When it happened to me i couldnt get the IAF into the plan so i hit obs and selected the desired inbound radial to the FAF from the IAF then used the range to FAF for a fix.. remember to go back to leg mode prior to FAF to proceed with the approach. :ugh:

[always inverted]

I say again then, there is no automatic waypoint sequencing after the mapp...:hmm:
After using them for the last 4 years and not sure how many approaches, I'm sure I know how to use them and what they do...:ugh:

Quote:
I disagree. The missed approach holding point IS sequenced after the missed approach point. The fact that the GPS doesn't load it automatically does not mean it is not sequenced. The sequence is suspended until YOU decide that you want to go to the missed approach holding point, then after pressing OBS/GOTO (depending on your make of unit) the sequence is continued.

[bentleg]

I say again then, there is no automatic waypoint sequencing after the mapp


I think we may have a terminology tangle here. The missed approach holding point IS sequenced (in the plan) after the missed approach point. However the KLN89B GPS under discussion here will not progress beyond the missed approach point automatically. You have to do something to reactivate the progression.

[AerocatS2A]

The same way we did a VOR missed approach before VORs. :rolleyes:

[always inverted]

:rolleyes::ugh:

Whether it is suspended or not, the fact remains that you dont have an automatic sequencing from the mapp, as I said, if you want to split hairs on the terminology then thats fine, I really cant be bothered. I was trying to help the original poster with something fairly simple till you made it hard...

Sure if you want, the hold waypoint may well be sequenced after the mapp point in the flight plan but how do you navigate to it if you do nothing... It will automaticly default to the aerodrome ref for the approach that was loaded, so therefore, I go back to my original point.
There is no automatic waypoint sequencing onto the mapp procedure, therefore you need to select the next waypoint and operate direct to it after comencing the mapp, then use the obs function if required.
Ie: start the climb, make the turn in the right direction iaw the mapp procedure, then direct to the next waypoint-if you have to intercept a specific track to the next waypoint then use the obs function after and set the required track and intercept it. Remember though, if you are navigating to a hold and the hold is flown (flown in obs) you will need to go back to leg mode to carry out another approach, we do it after the turn inbound (if conducting another app).
Remember that when you do go back to leg mode it will stay on the radial set by you (should be the inbound track for the hold) till you cross the fix. You will also need to be in leg mode to provide the sequencing from enr/terminal, to app arm and app act for the next app.

This is the way the company like it and it works every time, as long as there is raim etc...

Hope this has helped some...

[Mainframe]

Always Inverted,

totally agree with you. Automatic waypoint sequencing terminates at the missed approach point.

Simple, you are no longer flying the approach, you are either visual or if not, you've got a missed approach to fly.

The KLN89B will offer you the Missed Approach Holding point when you select "Go TO',
but before you press enter, you will need to comply with the missed approach instructions.

These instructions will often have you track straight ahead on the final approach heading while you climb to and attain a minimum altitude,

at which time you can then track to the MAPH waypoint. YIFL (Innisfail) immediately comes to mind as an example.

Simply, when you invoke (activate) an RNAV approach, the GPS will add a set of sequenced waypoints to your existing flight plan or in some (Garmin) to your destination.

The inserted waypoints start from a selected entry point e.g. WOLNA and finish at the Missed approach waypoint (WOLNM).

If you conduct the missed approach you will, after meeting certain requirements, track to H (WOLNH), and then decide to shoot an other approach,
an alternative approach, or divert to somewhere else.

Section 5 of the KLN89B manual (yes, you can download it) tells you all about what "always inverted" and others have already said.

There are a couple of very good articles on RNAV approaches, The Digest, 2005 had an excellent plain english 3 page write up.

The ATSB has also published a documented dealing with perceived pilot difficulties with GPS RNAV approach procedures.

Understood, properly trained and correctly interpreted, the RNAV approach is as good as a Localizer DME approach.

Not fully understood, not properly trained, or not correctly interpreted, it can be a life shortening experience.

Read your GPS manual, read the UK and other aviation authority websites, and understand whats really going on and you have a very safe and efficient instrument approach procedure.

I have flown hundreds of RNAV approaches using KLN89B, Trimble, Garmin 155, Garmin 300, Garmin 430, Garmin 530.

Even though the KLN89B is a very clever piece of equipment with enormous functionality, nothing compares to the less sophisticated and possibly more user friendly Garmin family.

Garmin tends to be more intuitive, a bit like Nokia mobile phones, use one model and you can stumble through the rest OK.

Good to see you endorsed on RNAV, seems to be mainly regional and mainline used with minimum take up of GA users, for various reasons.

p.s. I always try to fly an unfamiliar RNAV approach in visual conditions before I commit to doing that approach in IMC.

The Lockhart River Rwy 12 RNAV is quite exciting flown visually, you just know you've got to get the steps right if in IMC or you will bounce!

[alphacentauri]

always inverted and mainframe,
I think we all agree on the sequence of events after the missed approach is reached. We probably had a disagreement because of terminology. Thats cool, as I said I think we are all on the same page.:ok:

However I think the original poster raises an important issue of what the gps does or is going to do after you reach the missed approach holding point. That is why I described things like turn anticipation, and flyby waypoints. It appears the gps is doing something weird after the activation of the missed approach holding point, and that is impacting upon the pilots' ability to actually reach the missed approach holding point.

Looks like the answer for the KLN89 is to fly to the holding point in 'obs' mode.

I guess the lesson to be learnt is know your equipment, and until you are confident with it practice in VMC first.

alpha

[bentleg]

Thank you all for this informative explanation and discussion of my original query. :D

Bentleg

[always inverted]

Alphacenturi, no I dont think that the unit is doing anything wierd... The unit is doing what it is supposed to, it may well be you as the end user that does not fully understand what is happening. As I have said, I have been using the kln90b for the past nearly 5 years and it does what it should, well mostly.
The problem lies with using a similar unit, ie: kln89 and thinking that it will do the same things, this will lead to a cfit accident, as it has in the past.;)
Without reading the post again, from what I remember of it, it sounds like it is doing what it should when the unit is still in leg mode, thats why holds are flown in obs, to prevent the sequence to the next point after crossing the hold fix untill you are ready...

Everything with aviation comes back to the same acrynum K.I.S.S, keep it simple stupid... Dont get bogged down with the terminology if it confuses you, learn the way things work and then sort out the exact way to say it...

I will sometimes have a f/o who will see a master warning flasher and piss around deciding what the exact term is for it in the sop's/ manuals instead of saying what they are seeing - KISS... :hmm:

To the original poster, I hope I have helped.

[Number19]

always_inverted, what you're describing is the the kind of 'work around' that is put in place and followed, hopefully via SOPs, to deal with system limitations.

alpha's explanation deals with how the approach is constructed, why these limitations develop, and why the 'work around' you've described is necessary.

Incidentally, from an approach construction point of view alpha is spot on, but at a technical level that pilots aren't required to know. We just have to know how to make it do what we want.

So now we know how to fly it, and why it should be done that way.

A beautiful thing.


Now go outside and play.

[always inverted]

exactly, so surely then, the only things that the original poster needs to know is what they may not be doing correctly following the mapp, not the technical rubbish that goes into the internal operation of the unit.
Also Alpha may not be that up with the kln90b as they would know that it is not doing anything wierd...
Guessing that the proceedure in one king unit will be the same as another is very dangerous and I hope that my family are not on their flights... :=
Turn antisipate and flyby waypoints are irrelevant to this issue so I get the impression that alpha may be an instructer that talks alot but does not know that much... I may be wrong.
Surely if you knew the kln90b you would know that the holds are flown in obs...:ugh:(see the above comment again)

[SnowPanda]

I'm just wondering, having been highly impressed by the wealth of information I'd read at the start of this thread, how always inverted feels about dropping the intellectual standard back to primary school classroom level?

Perhaps if you're going to get so worked up over a PPrune thread again (which I highly suspect will happen, and soon) I suggest that you lie down for a while, then come back and read what's been written a second time before you make childish retorts. If you'd done that, you'd have noticed that what alpha actually said was:

"That is why I described things like turn anticipation, and flyby waypoints. It appears the gps is doing something weird after the activation ........ and that is impacting upon the pilots' ability to actually reach the missed approach holding point."

Perhaps on a second reading you might see that alpha doesn't believe the unit is doing something weird, but that the pilot in the situation may see it that way. Let's just say for example, someone who's been taught the work around and didn't actually understand how the unit itself worked. =)

On a slightly more positive note, I thought this forum was a wealth of information to anyone learning the ropes on these types of GPS units. Well done guys.

Snow.

[bentleg]

As the guy who asked the question in the first place , I did think what happened was odd and sought advice from those with experience.

The advice given on the technical side, waypoint anticipation etc, was appreciated and helped me understand what happened and how I can best manage it in the future. From my point of view it is all good stuff and not too technical.

I'll be having another go at the approach soon and look forward to trying out what I have learnt from this thread. Thanks again to all the contributors.