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PostPosted: Fri Nov 28, 2014 6:39 pm 
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Apologies guys... I have just skimmed this thread. Need to stop for a few and read closer.

Until then... :P

Nick M wrote:
• Is the lack of physical sensation in the sim a help or an obstacle in IMC flight?

Nick... I had two 25hr sim courses in a Frasca 141. I would say it was hardest flying I ever did because you absolutely had to stay on top of "everything" or risk being all over the place. I remember days going there, "oh joy, joy... what fun we will have today..." because it was a lot of work - and I was really wore out by session's end. In terms of helping / hurting, I would say the exercises we had to do in that Frasca is what enabled me to be very precise when shooting actual instrument approaches. After I had passed my Commercial / Instrument Checkride, I wouldn't think twice about flying in 200 & a half weather. Total confidence. That is... it did not take long at all to build that confidence (putting those skills to work) in actual IMC.

Nick M wrote:
I’m trying to analyse why my ILS approaches become unstable at this point. Obviously the needles are much more sensitive as I approach the localiser.

Oracle mentioned small changes. Half std rate turns, just a handful of degrees on the heading changes.

The VSI is going to tell you if you are going to depart from glidepath. Important to get the proper MP dialed in for the approach GS angle, so you have the right vertical speed / airspeed.

Nick M wrote:
• Have any of you found switching to a yoke significantly improves your instrument flying?

I think that would make a good thesis project (what do I know tho :P ) i.e. the effect of various types of flight controls wrt to learning instrument procedures in the sim.

I currently use an X-65F (and like it for what it does) but hope in a year or two to purchase some of PFC's stuff like their Cirrus Saab Yoke. some1 posted at avsim he likes it.

Nick M wrote:
• Does using an HSI encourage bad habits including the ‘needle-chasing’?

I don't think so. The final course @ Purdue we used a C172RG with an HSI. As you noted, it greatly simplifies the scan / better SA. I am not aware of any downsides to an HSI.

Nick M wrote:
In general though, I’d say my pitch control on the ILS is much worse than my lateral control. Partly this is because I struggle to have the aircraft perfectly trimmed without visual references. This leads me to a little thought/question for A2A:-

• Would it be technically feasible to introduce a ‘cheating’ trim indicator under one of the shift + number windows? By this I mean a graphical indicator of how much force the yoke is applying?

I am not quite sure what you are asking about here. Of course, the Art. Horz. gives you pitch info, as does the Airspeed & VSI.

I think it essential to know what vertical speed you need for the glideslope. And then know what power setting is needed to maintain your chosen approach airspeed and vertical descent rate. Set power / pitch just as you begin to intercept, trim out for your descent rate, then those tiny adjustments as necessary. That is why those exercises can be so useful. You can take that experience right on over to working the approach.

Also, I would suggest calm conditions at first. Work the wind in later.

If you go to the FAA's Terminal Procedures - Basic Search page, download the "Legends & General Information" pdf. On the last page of that is a "Climbs / Descents Table" that you can use to determine descent rate based on groundspeed and descent angle.

Hope all this makes sense,
-Rob

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PostPosted: Sat Nov 29, 2014 4:17 am 
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Great Ozzie wrote:
One needs to fly to the MAP hence needing a "fixed" approach speed from FAF to MAP and knowing that time e.g. that KMGJ ILS or LOC RWY 3. As Oracle mentioned, 90kias would be typical (and you should factor in winds for time).

One can climb early - but you are expected to fly to the MAP before executing the procedure.
I'm still a little bit confused about what is exactly the requirement here. I am in belief that in precision approach, the MAP is defined via decision height, and the timing is not particularly required. The missed approach procedures are very often of type that you should climb to certain altitude, or to fly to a certain fix then turn to somewhere. On ILS approaches, the planes may go around well before reaching DA of course (for example, because of uncertainty of clear runway in bad weather). In the chart here, which I find rather typical, the missed approach procedure is laid so that it will fly you to the airport anyway, regardless of where you actually perform the go-around. Some others say that you must make an immediate climbing left/right turn. I understand that this is how you fly it whether you've reached your minimums or not.

I just googled 'timing ils approach', and the first hit was (not surprisingly :mrgreen: ) John Deakin's rant on the topic. As I know a little of the subject, if anything this adds to my slight confusion here, as his points reflect how I understand the topic somewhat. Of course, flying sim there is little problem in doing what one wishes, but I'm yet to find a single missed approach procedure where going around before reaching DA/MAP would cause trouble plus it wouldn't have been specifically accounted for in the published procedure.

I need to add the instrument procedures to my long list of things to study..

-Esa

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PostPosted: Sat Nov 29, 2014 7:35 am 
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Thanks for the detailed reply Rob! :)

Afraid I had to look up the Frasca 141 which show how much I know! Gather though it's not a full motion type simulator but is intended for instrument training with an optional video system.

Great Ozzie wrote:
The VSI is going to tell you if you are going to depart from glidepath. Important to get the proper MP dialed in for the approach GS angle, so you have the right vertical speed / airspeed.

I've being flying approaches with the autopilot to verify the correct MP/RPM setting to use. (And confirming the vertical speed, which of course can be calculated.) My current pedestrian 75kt approaches need about -400fpm but I'm trying to avoid chasing the VSI too much either: especially with the added 'lag' physics built into this instrument. So many bad habits to avoid, and without an instructor peering over your shoulder, they're easy to get into.

As for yokes - well those Cirrus ones look great but if I do go down the yoke route, I think it'll be a cheap Saitek or CH job. I've been reading with interest some of the threads comparing the two. To me it seems that with a yoke it should be easier to add a roll correction without an inadvertent smidge of pitch input, which I think is part of my problem with my springy joystick. (I know - a bad workman, etc. etc. :mrgreen: )

Great Ozzie wrote:
I am not quite sure what you are asking about here.

Neither am I to be perfectly honest - I was thinking aloud really... To try and clarify a bit, I just wondered if it was possible to program a visual 'indicator' that would compensate for the lack of tactile feel in FSX with respect to whether the aircraft is properly trimmed. I've never used force-feedback hardware, but I guess FSX sends some sort of command to a force-feedback joystick telling it how hard to push (or pull). Would it be possible to encode this into a nifty little visual scale somewhere? To be honest, I don't really have a problem trimming in FSX in general (certainly not in the A2A stuff) but it becomes trickier in IMC without those outside visual references.

Great Ozzie wrote:
I think it essential to know what vertical speed you need for the glideslope. And then know what power setting is needed to maintain your chosen approach airspeed and vertical descent rate. Set power / pitch just as you begin to intercept, trim out for your descent rate, then those tiny adjustments as necessary. That is why those exercises can be so useful. You can take that experience right on over to working the approach.Also, I would suggest calm conditions at first. Work the wind in later.

Okay - this certainly reassures me that I've got the principals more-or-less sorted. It's just the execution that I need to work on. :) Oh, and you can rest assured that I'm not complicating matters with any winds or turbulence just yet - I'm a real cheat with FSX weather and definitely not a purist who insist on flying in real world conditions. :wink: (However, the rather brutal FSX ridge lift did give me a nasty surprise on the ILS at KLVK!)

Thanks again!
Nick


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PostPosted: Sat Nov 29, 2014 10:05 am 
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Nick, the transition to controlling an aircraft precisely using instruments from outside visual references is not easy. Trimming out the control forces has to be done by the feel of your stick exactly as it would be done in real life. The only difference is the resting position of the control when you are done trimming, and I am not paying attention to that. Yoke or otherwise, a force is felt the same way. If you continue to feel pressure on your fingers when you believe the aircraft is trimmed out, then you aren't done trimming. :) The forces can be very weak so I would say just keep at it, relax your fingers and feel what the joystick is telling you. Force feedback will not really make a difference here IMHO. Force feedback is more relevant when you are pulling Gs or in slow flight when the control forces change significantly. Personally, I don't feel it adds much value for this type of flying, though it has MASSIVE cool factor! :)

It is especially important to use all the instruments together and to shift to scanning certain instruments for frequently for a few moments when performing certain tasks. The VSI is not a primary instrument for pitch control. It has too much latency and you'll end up all over the place. The Attitude Indicator is your go to guy to make sure that you are holding steady. You need to be at a resolution where you can read that instrument well. It takes very little movement of the horizon to make big changes in the VSI. Hold the artificial horizon steady and then check the VSI to see how things are coming together.

In instrument conditions, the last thing you want to listen to is your balance organs and seat of pants for trimming the aircraft. That information is very dangerous without visual references and can put you in an out of control situation. Learning to trust the instruments and ignore these sensations is a big part of the initial training.

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PostPosted: Sat Nov 29, 2014 11:12 am 
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Thanks Oracle. Some useful stuff for me to bear in mind there. :) The only thing I tend to disagree with a bit is the "feel what the joystick is telling you" remark. Basically it's just trying to return to its centred position with its beefy springs, irrespective of what the aircraft is up to! It'll behave exactly the same when the aircraft is parked on the ground or if we're badly out-of-trim at 120 kts.

Having said that, I think I know what you're getting at: we have to rather sensitively allow our controls to come back to that centred position whilst trimming-out imaginary control forces, which are sort-of represented by the joystick's springiness! :wink:

Oracle427 wrote:
The Attitude Indicator is your go to guy to make sure that you are holding steady. You need to be at a resolution where you can read that instrument well. It takes very little movement of the horizon to make big changes in the VSI.

Yes indeed! Since creating a nice enlarged view of the primary instruments and really looking at that AI, I've noticed a marked improvement in my performance. Again, using the autopilot to fly a few ILS approaches and trying to memorize exactly the attitude on the AI has helped me a bit too.

Thanks again guys for your advice so far! :D
Nick


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PostPosted: Sat Nov 29, 2014 12:41 pm 
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It does depend on the stick I guess. On my stick the pressure is fairly constant whether you deflect all the way or half way. Some sticks do increase forces as you increase deflection which can help one feel how far off they are. But you see the point, which is to get neutral pressure or the stick centered via trim.

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PostPosted: Sat Nov 29, 2014 2:06 pm 
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AKar wrote:
I am in belief that in precision approach, the MAP is defined via decision height, and the timing is not particularly required.

That's correct, Esa. But... how to know where the MAP is? If you do the timing, you know where you cross a defined MAP to prevent that "abnormally early turn" (see the AIM below).

If executing a missed approach prior to reaching the MAP, fly the lateral navigation path of the instrument procedure to the MAP. Climb to the altitude specified in the missed approach procedure, except when a maximum altitude is specified between the final approach fix (FAF) and the MAP. In that case, comply with the maximum altitude restriction. Note, this may require a continued descent on the final approach.
(5−5−5. Missed Approach)

b. Obstacle protection for missed approach is predicated on the missed approach being initiated at the decision altitude/height (DA/H) or at the missed approach point and not lower than minimum descent altitude (MDA).

Reasonable buffers are provided for normal maneuvers. However, no consideration is given to an abnormally early turn. Therefore, when an early missed approach is executed, pilots should, unless otherwise cleared by ATC, fly the IAP as specified on the approach plate to the missed approach point at or above the MDA or DH before executing a turning maneuver.

(5−4−21. Missed Approach)

And, as Deakin mentions in that article, it's a good habit to start the timer over the FAF (I'm not so concerned with it being a distraction - actually the opposite). I think he's all wound up about the FAA busting an applicant over not starting the timer. It is pretty harsh.

Oracle427 wrote:
The VSI is not a primary instrument for pitch control. It has too much latency and you'll end up all over the place.

In certain phases of flight, the FAA's Instrument Flying Handbook will beg to differ.

Also, I think this AOPA Flight Training article by Ralph Butcher will speak similarly; Instrument Training: Instrument Interpretation. Ralph Butcher has a couple other articles that may be of some use: The essence of IFR and a another 4 Step Instrument Scan (which I confess I am still working on figuring out his method).

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PostPosted: Sat Nov 29, 2014 2:52 pm 
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Thanks for your patience Rob! I need to dig deeper to the instrument stuff as it really is quite unknown for me - somewhat annoying, as I've spent quite a good time on understanding how the equipment itself works! :)

Around here quite many missed approach procedures work so that you fly the approach track until certain DME before first turn, so it really doesn't matter whether you time it or not in that sense. I'm still quite dubious about how practical it is to rely on timing, as with many airplanes, you really need to go through some configurations when going around, and accelerate quite a bit while doing so. Not necessarily with GA airplanes, but if we think it ad absurdum, take F-18 as an example - in principle, the procedure still applies, and you don't want to voluntarily climb that thing in approach configuration at 128 knots or so with lift-over-drag of a bowling ball... Airliners are somewhere in between, usual go-around being at around V2 plus something - anyways above the approach speed.

Of course, in practice it is often possible to use common sense when going missed, quite often when the visibility is really bad, down to categories, the actual layer is quite shallow, allowing you to fly the missed approach in sunny VMC.

-Esa

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PostPosted: Sat Nov 29, 2014 7:26 pm 
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AKar wrote:
Thanks for your patience Rob!

Man... now you got me thinking I'm being a bit snooty in my posts. :lol: I'm like you guys... I thoroughly enjoy discussing this stuff.

AKar wrote:
I need to dig deeper to the instrument stuff as it really is quite unknown for me - somewhat annoying, as I've spent quite a good time on understanding how the equipment itself works! :)

And there is quite a bit... agreed. Truth be told, my reasoning to go after the A&P was so I had a good idea how the stuff worked to be a better pilot.

AKar wrote:
Around here quite many missed approach procedures work so that you fly the approach track until certain DME before first turn, so it really doesn't matter whether you time it or not in that sense. I'm still quite dubious about how practical it is to rely on timing, as with many airplanes, you really need to go through some configurations when going around, and accelerate quite a bit while doing so.

If you do time ILS, with or without DME, the way I look at it, it is just a measure of redundancy. Going back Oracle's example of the KMGJ ILS or LOC RWY 3, briefing for both (ILS & LOC) fairly simple. After the FAF, there is only two other altitudes to be concerned with... one "500 above" minimums (circling) and the other "300 above" (LOC). If it were a complicated step-down procedure, and I'm flying the ILS then lose the GS after intercept... yeah why try to mess with that - missed approach and setup for the LOC. But the time gives me a good estimate of where I am; "ok... 90kias with a 30 knot tailwind. So a minute and a half in... I'll make the initial climb and in 30 seconds I'll be over the airport and can continue the rest of the procedure."

Someone posted a link to a "New Hampshire CAP C182T Profiles Guide". It is very useful... you can see for either a precision or non-precision approach, the configuration from IAF to MAP is 90kias and 10° Flaps.

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PostPosted: Sat Nov 29, 2014 7:56 pm 
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Nick M wrote:
In general, the main points I’ve taken on board when flying the ILS are ‘don’t chase the needles – fly a heading and V/S’ and ‘scan like crazy’! To be fair this usually works pretty well until the last 300-400ft before minimums. At this point I find myself tending to overcorrect and some fairly extreme attitudes can result. (I should add that in FSX I tend to set-up a rather artificial scenario where I need to fly right down to about 220ft AGL on instruments before I get any visual reference with the runway environment.)


I used to over correct all the time myself--and this was in real life in thick IMC, flying high perf. a/c. :o. What I found works for me is as follows:
-Relax your gaze on your instrument. It's not so much a matter of scan like crazy, because I find that if you stress yourself too much, you will end up fixating, even for a split second, which will completely mess you up
-Keep the bank angles below 10 degrees. Bank only as much as the degrees of heading you are correcting. If you need to correct 5 degrees left on heading, for instance, bank about 5 degrees.
-Generally speaking, following glideslope is the easiest part of the ILS. Take half your groundspeed, add a zero, to get a suggested feet-per-minute descent. Don't exceed 1000 fpm.
-TRIM the aircraft. Depending on how many trims you have, you might have to trim for pitch, roll, AND yaw. I found out the hard way that the less trimmed the aircraft is, the more pain in the butt it is to keep to the needles
-If you have a GPS, incorporate that into your scan. your TRK and your DTK should match. If they do not, then your localizer needle will slide out
-Flying the localizer can be tough! If I'm centered, and my needle starts to drift slowly left/right, I do 2-3 degree corrections. If the localizer runs away, I might have to do 10 degree corrections at a time, but once it's stabilized, the bracketing should be limited to the least amount of degrees as possible.
-There is nothing worst in an ILS approach than strong gusting winds. As you descend lower, keep in mind that wind direction and speed may change, so you will always have to be able to catch slight movements on the localizer.
-It's easy to chase the needles as you get closer to the runway. Really, the trick is to get both needles as centred as possible when you are far out, because you are more or less flying into a funnel.

Quote:
• Is the lack of physical sensation in the sim a help or an obstacle in IMC flight? (I realise there’s not much I can do about this, but just interested to hear opinions.)

I’m trying to analyse why my ILS approaches become unstable at this point. Obviously the needles are much more sensitive as I approach the localiser. However, I feel the culprit is partly that using a rather springy joystick (Logitech Extreme 3D Pro) I tend to introduce an unwanted pitch command whilst trying to adjust heading (and vise-versa), So, question two:-


Springy joysticks can make it tough. However, I find that having a lack of physical sensation isn't an adverse factor. In real IMC flight, even when you know not to trust your bodily senses, there are days when it will affect you a bit anyways. One might think they are constantly in a bank when in fact they are not, and that messes things up.

Quote:
• Have any of you found switching to a yoke significantly improves your instrument flying?

The reason why the C182 is my preferred instrument platform is, of course, because of A2A’s excellent rendition of the KI 525A HSI. I find that (presumably because this simplifies my scan) my lateral control when using it is a lot better and the HSI is certainly a wonderful instrument. However, here’s another question:-



I actually don't use a yoke on my home PC. Joystick works just fine, but you have to trim it out and stuff all the same.

Quote:
• Does using an HSI encourage bad habits including the ‘needle-chasing’? I’m not sure…

In general though, I’d say my pitch control on the ILS is much worse than my lateral control. Partly this is because I struggle to have the aircraft perfectly trimmed without visual references. This leads me to a little thought/question for A2A:-


Yeah, the trim is a big thing. HUGE even. One thing I do find is that trimming behind a PC is a bit more difficult than trimming in a real airplane, since in a real airplane, you can pretty much man-handle a giant trim wheel depending on the aircraft. It just takes a bit of practice.

If you are trimmed correctly, your aircraft should maintain a constant rate of descent without requiring more than a couple fingers in making small changes to the aircraft's attitude.

Quote:
• Would it be technically feasible to introduce a ‘cheating’ trim indicator under one of the shift + number windows? By this I mean a graphical indicator of how much force the yoke is applying? (Perhaps this info is available in the sim for force-feedback hardware.) I’d envisioned a kind of discreet vertical slider which would become centred as the aircraft moves towards being properly in trim and one can relax control input.


You can, but if you feel resistance from the springs on your joystick, it's more or less the same thing. If you trim properly, your joystick should be pretty much in it's centered/neutral position, and you aren't constantly holding onto the stick, so-to-speak. ILS approaches used to be a thing that made me death-grip my controls, which is exactly the thing you shouldn't be doing.

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PostPosted: Sun Nov 30, 2014 6:01 am 
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Rocket_Bird - thanks for taking the time to post. I'm trying to take all the tips in this thread on board. Your advice to "bank only as much as the degrees of heading you are correcting" sounds eminently sensible. Your initial sentence also makes me feel a bit better about my difficulties hand-flying the ILS.

Rocket_Bird wrote:
Generally speaking, following glideslope is the easiest part of the ILS.

That's interesting, because I seem to find following the glideslope is trickier than tracking the localiser - certainly with the HSI. If I look at the 'flight analysis' tool after flying my approach, there are noticeably more vertical wobbles than excursions left or right. However, having said that, as previously mentioned I'm flying without winds at the moment.

Your remarks about trim are well taken. I do think part of my problem is that I continually seem to be chasing the perfect 'in-trim' configuration. I use the A2A input configurator to assign the electric trim switches to joystick buttons. Perhaps I'm even becoming to fixated on trimming the aircraft?

Time for some more practice... :wink:

Cheers,
Nick

P.S. I'm reading the discussion on missed-approach timing/procedures with interest too fellas. With my rather artificial 'IMC training weather scenario', I always know I'll see the runway light just before minimums, but hopefully I'll move on to more realistic procedures in time.

Great Ozzie wrote:
Also, I think this AOPA Flight Training article by Ralph Butcher will speak similarly; Instrument Training: Instrument Interpretation. Ralph Butcher has a couple other articles that may be of some use: The essence of IFR and a another 4 Step Instrument Scan (which I confess I am still working on figuring out his method).

Thanks for these links Rob - I certainly need to get a better understanding of developing an effective instrument scan.


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PostPosted: Sun Dec 14, 2014 9:36 am 
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As you get closer to the ILS/GS the needles get very sensitive. You should be well set up at this point and as you get to the very end it would be better to hold your attitude and heading rather than chase the needles. Get established on the needles and then as you get near the end hold that attitude and heading. The "cone" on the signal gets very narrow at the end, and the needles get jumpy because a very small positional error is a large angular error. The needles measure angles from centerline rather than distance.

I ensure it is trimmed out at a nice stable approach speed. Trim is very very important to get a stable approach speed. Trim. Trim. Trim. Use power to control rate of descent. The rule of thumb is ground speed in knots x 5 is the feet per minute of descent to get 3 degree slope. So keep in mind your headwind. Practice the power settings so that you can set the aircraft up in advance to get the proper slope. If you know that 16", full fine, gear down, and 104 knots gives you a 3 degree slope then you set that and make small corrections. Once you are established you can use small pitch corrections to get centered. Also, use the trim. Did I mention the trim? If the trim is set and your descent rate is fixed your scan can focus on the heading and ILS more. TRIM.

I set up the heading by guessing using my approach speed and the cross wind. Then make small (no more than 5 degree corrections) to heading and check the localizer needle. Once you get it to stop moving note the heading - that is what keeps it stable. Intercept the needle and take up the heading that leads to the needle not moving. The key is to scan the instruments to maintain a constant attitude and heading, and then glance at the needle to see what it is doing. Fly the heading and attitude that keeps the needle steady. Consider using the rudder only for small one degree adjustments. The world will not end if the ball slips off the mark for a few seconds. Also, do not fuss with the heading indicate or worry about precession during the final. Just fly whatever heading works.

When you get close to the ILS the needles will get jumpy. Focus on keeping the heading and attitude steady and let the needles go. Start looking for the runway as you get to the DH. Single pilot IMC approaches to low minimums is ... stressful. Having a co-pilot or passenger call out the altitudes, timing, and look for the runway is such a relief. If you don't see the runway at the DH, push in throttle and initiate the missed approach. There is almost no margin on a low ILS approach to minimums.

Yes, you must start a timer from the final approach fix. Many approaches, especially NDB approaches, have no other method of estimating where the MAP is. So if you descend to the MDA and fly towards the runway, how would you know other than the timing? Note that the time depends on the ground-speed. Also, if there is no DME or GPS, you can't really tell any other way. Some places can use intersections from other nav-aids, but that is going to depend on those beacons working, and how many eye balls do you have in the cockpit? You can probably set the timer up well in advance when you do your approach briefing based on the ATIS and your expected ground-speed. Then it is just a matter of hitting the button when you pass the marker, beacon, fix, or what ever. It is also nice if it has a beeper or something so you don't have to visually monitor it. As others have mentioned, if everything shuts down on the approach you have the timer to let you know when to give up. When it starts beeping you should check for the runway.

Did I mention that trim is important?

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PostPosted: Mon Dec 15, 2014 9:11 am 
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Thanks William for the post.

William Hughes wrote:
Single pilot IMC approaches to low minimums is ... stressful.
Yes - I'm probably setting myself quite a steep learning curve with the low minimums that I've chosen to practice in. With respect to calling out altitudes, one think I've taken to doing is using the altitude alerter feature of the KAP140 as a audible cue at the decision altitude (rounded up to the nearest 100ft anyway). Not sure if this would be a valid/recommended real world technique, but it's helpful at those approaches without a middle marker.

William Hughes wrote:
Did I mention that trim is important?
Yes - trim! I noted in an earlier post that I was having a bit more difficulty trimming the aircraft in IMC (I'm still blaming the lack of tactile feedback). Recently I've taken to flying most of my ILS IMC approaches in the Cherokee. In spite of the more basic avionics (in other words, no HSI) I don't seem to fly the approaches any worse (if anything they've been better). I wonder if this is because I'm a bit more used to the feel of the pitch trim in the simulated Cherokee. Or am I less inclined to chase the needles when they're less prominent in the scan?

With respect to timings to the MAP, once I'm a bit happier with my precision approached, I'll have to start working on flying my non-precision ones a bit more realistically too... :wink:

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PostPosted: Mon Dec 15, 2014 4:17 pm 
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Location: Vancouver, BC
Something to think about: decision heights (DH) are used for precision approaches with vertical guidance. Since you are on the appropriate slope, when you arrive at the decision height, you should be at or very near the the missed approach point (MAP) anyway, so the timer is not quite so important. As you get to the altitude look for the runway.

Minimum descent altitudes (MDA) are for non-precision approaches. So if there is no precision guidance you can step down to the appropriate minimum altitude early and cruise along. This is not recommended practice - the preferred approach is to set up the slope required and fly that - but the step approach is still in use. In this case you need something to tell you when to look for the runway and the timer is it.

Any resource at all that helps should be used (an altitude warning is a great idea) but you must meet the minimum accepted practice at all times. Prepare a checklist that you can scan quickly while doing this that has all your steps.

If you can get access to the real approach plates, a CAPGEN, and a handbook of some kind this will all make a lot more sense. Those are the Canadian terms, sorry, I don't know the American ones. You can usually get expired plates for the asking at small airports and flight schools.

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PostPosted: Mon Dec 15, 2014 4:49 pm 
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Joined: Mon Sep 02, 2013 7:30 pm
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Location: Typically hanging around N07, 12N, KLDJ, KCDW
Plates are free on the FAA site. Download and print away or keep a screen open in your smartphone or tablet with the details.

I'm doing my IFR right now along with a couple of friends and we're all wiring with different instructors in different schools or privately arrangements. In all cases we're being taught to descend at to the next lower altitude at a rate of 800FPM. The idea being that you will not benefit from remaining higher for a longer period of time in non precision approach which naturally has higher minimums than the precision approach. Not saying any other way is wrong, but that is the reasoning.

On a precision approach the idea to use a timer anyway is because you can have a failure of the glideslope at which point the DH is no longer applicable and unsafe. It's nicer to have an alternate means of finding the MAP in this case, but having the timer going is good practice in my view.

I had a simulated GPS failure on the G1000 yesterday going into KMMU on the ILS 23. It created two situations, one which I was prepared for and the other for which I was not. The instructor said I had not made visual contact with the runway so I needed to go missed.

I had the timer going so I could determine where the MAP is just in case I had lost the glideslope. Without the GPS I have no other means if I hadn't been timing. I however had no way to locate the holding fix at CAT NDB! I had to request vectors to an alternate, not fun.

Always plan ahead and manage your risks. :)

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