How to switch from ILS G/S approach to LVCH and HDG

[tjeuten 6]

Hey,

 

sorry if this has been asked before, couldn't find it...

 

So here I was descending on the VOR/LOC and G/S at LOWI's LOC EAST approach, scheduling a circle-to-land for RWY 08, according to the published procedures.

 

That procedure tells to turn to heading 230 at AB NDB. As said, I was descending on the G/S coupled with the autopilot (CMD A), so at AB NDB I hit the HDG button on the MCP, to make the plane turn to 230 which was set in the MCP .... but nothing happened. Also, wanted to LVLCH to 3700 but that didn't work either.

 

The only way to achieve the desired result was to completely disconnect the autopilot and fly the rest of the procedure manually (in which I succeeded pretty well but nonetheless the A/P would have been some help).

 

So my question: I guess there's some kind of protection mechanism that once your in ILS mode (VOR/LOC and G/S captured), you cannot just get out of it easily, but I guess there must be some way to override it and just go back to a plain HDG and LVLCH mode, isn't there ? If so, how ?

 

Thanks for any help, appreciated...

 

Mathieu

[G-CIVA 62]

Turn OFF the Autopilot (if engaged), fly the aeroplane & recycle the Flight Directors i.e. switch them OFF then ON again - ensuring the Flight Director on your side of the MCP is recycled first in order to remain the 'Master' indicated by a small green light on the MA symbology adjacent to the Flight Director on your side of the MCP.

 

You should then be free to select alternative ROLL/PITCH Modes & once the aircraft is correctly 'trimmed out' you can re-engage the automatics.

[Paul_Smith 92]

I am open to correction here, but I am pretty sure that because circle to land is not a precision approach, you should not be using the automatics.

[MED1473 18]

Hi all. Yes this has been discussed before and not long ago. The post if you look for it explains it quite well.

Anyway in a nutshell, once the airplane is in APP mode the only way to get out of it is to either turn the whole thing off (unrealistic) or hit the TOGA button (not applicable). There are ways to exit the App mode explained in the manuals (can't remember where, see the other post as mentioned) but just notice that if you're flying the circle to land to rwy8 at lowi you have no need to use the app mode for the descent, can do it very well in vnav. If you fly in with the app mode your only option is to disconnect the AP at ab and fly the rest manually.

Hope it helps

[hopskip 253]

I thought Innsbruck's instrument approach was a LOC/DME and not an ILS with Glideslope? Therefore my choise would be using the VNAV/LNAV after joinig the LOC course at or before 21DME at 9500ft, with raw data (Localizer mode) on the PNF side NAV display, and DME/VOR info set on the PF side Nav display but in Map mode.

 

That gives you the 3.7degree decent glideslope from the VNAV.

 

I realise there are some addons out there that put a full Glideslope into the sim, and I can't remember entirely but maybe default FSX puts a full ILS Glideslope there too, but IRL (and on the aerosoft addon LOWI scenery for FSX) there is only Localizer.

 

So for the LLZ-East approach I'd insert the LLZ26 approach into the FMS, fix any discontinuities around RTT (Rattenburg NDB), and expect to fly overhead RTT at about 10000ft and 200 or less kts.

 

The FMS may put you in a hold at RTT or just send you direct to the "Vector" waypoint just before the intercept.

The next waypoint (I think navigaph data calls it OEV21) is on the 074 radial of OEV (111.10) at 21DME and at this point you should be at 9500 and have at least flap 5 out and be on green dot speed for that flap. You then fly the 254° inbound on the Localizer, return to VNAV/LNAV (if you left it to slow down) with Speed Intervene (My preference, pre-set VNAV/speed window closed may be an option).

 

Approaching 19DME you would set the MCP Altitude to 8700, at 17DME MCP altitude to 7500

At 19 dme reset MCP to 5500, and further down to 4500 at 9DME. You want to have gear down and be slowing up to 160kts with flap down to as much as 25 in this section. Complete the landing checklists here holding at flaps.

 

At 9DME you are overhead AB (Absam) and it's time to turn left to 230. I usually go full manual here and set my MCP altitude to the missed approach of 9500ft and MCP heading to 074, but it is possible to use the MCP to fly the downwind leg if you want.

 

To do this you would turn MCP heading to 230 and set MCP altitude to 3700. You want to be slowing up to your approach speed by now, Vref+additive.

 

NDB "INN" (420mhz) is your aiming point, and before you pass to the south of this point turn heading 264 (downwind).

 

With your VOR/Nav1 still set to 111.10, wait till you pass 3.5DME outbound before you start turning. if you turn before this you will end up high and overshooting the runway centreline. As you pass about 3DME you will start to worry about the mountain ahead of you. Play chicken with it.

 

At 3.5DME you turn, don't decend more than 300ft/min in the turn, and nail your Vref+additive here and keep the speed. This is all manual flying now, so if you have time before you turn, hit up the Missed approach info (9500ft/074°) in the FMS incase you go around.

 

Automatics can't help you once you pass 3.5DME on the downwind leg.

 

 

-----------------------------------------------------

Not specific to Innsbruck but:

 

--- if you are in APP mode (and the LOC/Glideslope are tracking an ILS) you have to either go into TO/GA (Go around) mode or turn off both flight directors to leave APP mode.

 

 

Trent Hopkinson

[G-CIVA 62]

Notwithstanding all the points aimed specifically toward the circle to land manoevure for RWY 08 @ Innsbruck....

 

Anyway in a nutshell, once the airplane is in APP mode the only way to get out of it is to either turn the whole thing off (unrealistic) or hit the TOGA button (not applicable). There are ways to exit the App mode explained in the manuals can't remember where

 

Ermmm...why would disengaging the AP & recycling the FD or 'turn the whole thing off' be as you say 'urealistic' even though you can't remember where the reference is in the manuals?

 

I agree that pressing the TO/GA Switches on this occasion is not appropriate as would be retuning the associated NAV Receiver..which leaves the choice of one.....

 

From the PMDG 737NGX FCOM vol 2, Ch 4, Automatic Flight (4.10.16, pp 200/1240)

 

After localizer and glideslope capture, APP mode can be disengaged by:

• pushing a TO/GA switch

• disengaging autopilot(s) and turning off both F/D switches

• retuning the VHF NAV receiver.

 

I can already feel the flames of righteous indignation for daring to challenge a comment with a factual quote from the reference material that comes with the product from Boeing.

[hopskip 253]

From the PMDG 737NGX FCOM vol 2, Ch 4, Automatic Flight (4.10.16, pp 200/1240)

 

After localizer and glideslope capture, APP mode can be disengaged by:

• pushing a TO/GA switch

• disengaging autopilot(s) and turning off both F/D switches

• retuning the VHF NAV receiver.

 

 

Forgot that last option. Of course the APP mode won't be able to stay engaged if the ILS frequency is removed from the NAV receivers (1 and 2). I havn't done it this way before, I might have to check out how the F/D responds to that. (Does it revert to HDG/Alt hold? HDG/Vert Spd? CWS? Disconnect autopilot entirely?)

 

Good catch there.

 

Although "Disconnecting autopilot and turning both Flight Directors off" is my favoured method, there's no mistaking what the aircraft is doing then and the "What is it doing now" question is very easily answered. Answer: Responding to yoke, rudder and throttle inputs.

 

Trent Hopkinson

[rocketfs 2]

I am open to correction here, but I am pretty sure that because circle to land is not a precision approach, you should not be using the automatics.

 

What's wrong with using an autopilot for a circling approach?

 

Bert Van Bulck

 

There are a few options to get out of APP mode: recycle Flight Directors, change beacon frequency etc.

 

But LOWI doesn't have an ILS (although FSX shows it). FLy it LNAV/VNAV or VOR LOC/VERT SPEED.

That will prevent it from following the "ILS" and flying through MDA.

 

Bert Van Bulck

[tjeuten 6]

Hey all,

 

thanks for all replies, and especially those indicating how to get out of APP mode.

 

To all those saying that LOWI doesn't have a glideslope, I honestly think you are incorrect. Take a look at the charts (dating from 2011): http://cartasaereas....cartas/LOWI.pdf

 

Scroll down to LOC/DME EAST approach plate. In the profile view, it clearly says "GS indication available between D18.2 OEV and DA".

 

Btw I'm using the 1.20 version of Aerosoft's Approaching Innsbruck.

[wanabflyer 53]

Hey all,

 

thanks for all replies, and especially those indicating how to get out of APP mode.

 

To all those saying that LOWI doesn't have a glideslope, I honestly think you are incorrect. Take a look at the charts (dating from 2011):

 

Scroll down to LOC/DME EAST approach plate. In the profile view, it clearly says "GS indication available between D18.2 OEV and DA".

 

Maybe what Bert is saying is that there is no ILS at LOWI in "RW Flight" ?

 

Regards,

[MED1473 18]

Ermmm...why would disengaging the AP & recycling the FD or 'turn the whole thing off' be as you say 'urealistic' even though you can't remember where the reference is in the manuals?

 

I agree that pressing the TO/GA Switches on this occasion is not appropriate as would be retuning the associated NAV Receiver..which leaves the choice of one.....

 

 

Steve first of all thanks for fishing the reference out of the FCOM, I was walking back home from work and since I'm not God I couldn't remember the specific chapter and page.

I think it's unrealistic because seems fumbly to me. Turning everything off and back on. Plus why would you fly a circle to land with the AP? Especially Near high terrain? I am unsure how you would do it in reality. I am pretty certain that a circle to land procedure is flown manually after turning the ap off and not re-engaging the ap.

Just my personal view, I do not mean it to be set in stone, just an open thought

[G-CIVA 62]

Fair enough, I guess my comment was a little 'throwaway' & attempts at witty sarcasm have never been my strong point...I did not want to get into a debate about the merits of circle to land & the Autopilot/Autothrottle because as we can see it opens up a huge can of worms & each circle to land is different...& that's why I kept my response to the OP to the point.

 

Yep it could be seen as a 'fiddly' procedure but with two spare hands in a RW flight deck I guess it can be accomplished in seconds few. I am lucky because as a dual monitor user my 2d MCP is undocked on to the other screen so the mouse movement is not so difficult...almost as simple as if I had a piece of hardware like an MCP sat infront of me.

 

Best

[MED1473 18]

Hey Steve no worries. It's actually a good point that I hope somebodymore knowledgeable can clarify for us. What are the SOPs concerning leaving the APP mode? Is it allowed in other cases than a non standard event? If so what are the ways?

In MY point of view selecting the APP mode is a commitment to land and in case of using a gs for a circle to land procedure the way I always thought was right to do it was to follow the gs, disconnect the AP and circle in manual

[G-CIVA 62]

This might help ....

 

http://www.smartcockpit.com/aircraft-ressources/CIRCLING_APPROACH_2_ENG-B738_RYR_rev_4_0-JAN_09.html

 

I can see a couple of opportunities in there for disconnection of A/P & A/T.

[iainsmith 9]

What's wrong with using an autopilot for a circling approach?

 

What's wrong with actually flying the aircraft? Pilots are supposed to be able to do that!

 

Iain