How far into the approach with an autopilot

jssmith.lh

jssmith.lh

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I searched around and couldn't find anything on this. I'm sure someone will prove me wrong :->

I recently went from an airplane with a wing leveler to one with GPSS/coupled approach.
At first I used heading and vs mode to the FAF. I started playing around with coupled approaches and thought way cool. Now I'm wondering about coupled approaches to MAP. Thought I would see what others are doing and why.

Fire away!
 
I have flown training mission approaches to mins with AP, then use GPSS to take me to holding after missed... with Century 2000
 
You need to make part of your checklist to disengage the autopilot. Can get real funny when you are trying to land on your own.
 
Groundpounder said:
If you read the manual for your autopilot it will define when you can engage it, and how long you can keep it engaged for.
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Exactly, you need to read the supplement for your equipment. Depending on the equipment installed, some will let you fly coupled all the way down the ILS, some have minimum altitude restrictions.
 
benyflyguy said:
You need to make part of your checklist to disengage the autopilot. Can get real funny when you are trying to land on your own.
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Yup, the last thing you want is a big trim adjustment at minimums.....when you push that red button.:confused:
 
benyflyguy said:
You need to make part of your checklist to disengage the autopilot. Can get real funny when you are trying to land on your own.
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It can also be real important for a missed approach, for example on a G1000-equipped airplane if it doesn't have a go-around button.
 
Radar Contact said:
Mine is good to go on passing 200ft agl on departure and has to come off at 200 agl on arrival. Sometimes I do both but usually I hand fly a bit more. Depends on my mood and the Wx.
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Just that including the miss and hold with an experimental RV10 and panel. Have to practice both to stay proficient in both.

G430w, GRT HXr, TruTrak


Sent from my iPad using Tapatalk Pro
 
From what I read in the 55x manual it looks like it’s ok to the map. I was just wondering even if it’s good to the map, do you use your autopilot all the way there or turn it off at some intermediate point.
 
jssmith.lh said:
From what I read in the 55x manual it looks like it’s ok to the map. I was just wondering even if it’s good to the map, do you use your autopilot all the way there or turn it off at some intermediate point.
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It's about personal choice. One of the choice points is simple - do you want to hand-fly the FAS as a proficiency exercise? Or, vice versa, if you typically hand-fly, do you want to use the autopilot all the way down as a proficiency exercise?
 
First, you need to read the flight manual supplement that came with your autopilot. It's going to put the legal limits on it.

For proficiency use, I always do each approach twice. Once entirely hand flown (or at least from the point I intercept the approach) and one entirely coupled to the autopilot. The last thing I want is to not understand "what the **#@$* thing is doing" while on an approach.

In actual flight, if I start with the autopilot, I'll keep it on until I break out.
 
I have an STEC 30. Read the manual and the limitation is to the Middle Marker for localizer. I guess that could be inferred to be 200 feet agl.
 
jssmith.lh said:
I searched around and couldn't find anything on this. I'm sure someone will prove me wrong :->

I recently went from an airplane with a wing leveler to one with GPSS/coupled approach.
At first I used heading and vs mode to the FAF. I started playing around with coupled approaches and thought way cool. Now I'm wondering about coupled approaches to MAP. Thought I would see what others are doing and why.
Click to expand...

With passengers: I'll pretty much leave it on at least until we break out, every time.

By myself: I'll probably start to hand-fly as soon as I'm finished briefing the approach.

With a CFII on board: The dang thing seems to never work. :rofl:
 
The GFC500 will fly legally to minimums and fly the missed with the go around button. Sometimes I do. Sometimes I don't use it at all.

I'll sometimes help with manual trim to get in a better landing trim
 
Depends. The GFC 700 will do as the 500 does, it will fly to minimums, then fly the missed with a push of the go around button. It's important not to be figuring this out while on a real approach. Stay way ahead of the airplane.
 
Hang 4 said:
I have an STEC 30. Read the manual and the limitation is to the Middle Marker for localizer. I guess that could be inferred to be 200 feet agl.
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What's a middle marker ;) But seriously, the manual doesn't say that. In fact, it implies the opposite. They have different procedures for handling missed approaches that occur before and after the middle marker.
 
flyingron said:
What's a middle marker ;) But seriously, the manual doesn't say that. In fact, it implies the opposite. They have different procedures for handling missed approaches that occur before and after the middle marker.
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Fair point. What is says "at middle maker, if missed approach declared, disconnect autopilot". Then a missed procedure. What I can't find is a "disconnect below X altitude". After all the conniption fits about using a trutrack below 700 ft agl, I was curious what the guidance was for mine. Aside from referencing a navaid that is disappearing, not a lot that I can find.
 
Radar Contact said:
Mine is good to go on passing 200ft agl on departure and has to come off at 200 agl on arrival. Sometimes I do both but usually I hand fly a bit more. Depends on my mood and the Wx.
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in all the 310 pilot videos, why haven't we seen a single approach in imc? the people want to know!
 
I am new to the autopilot/approach scene. My typical (1300 hrs) has always been hand fly, at least until this plane. I have been disconnecting at 500 feet for consistent operation during my practice approaches.
 
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flyingron said:
What's a middle marker ;) But seriously, the manual doesn't say that. In fact, it implies the opposite. They have different procedures for handling missed approaches that occur before and after the middle marker.
Click to expand...

Hang 4 said:
Fair point. What is says "at middle maker, if missed approach declared, disconnect autopilot". Then a missed procedure. What I can't find is a "disconnect below X altitude". After all the conniption fits about using a trutrack below 700 ft agl, I was curious what the guidance was for mine. Aside from referencing a navaid that is disappearing, not a lot that I can find.
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With an STEC30, especially if you have GPSS, the best thing to fly is an RNAV anyway - no "middle marker" or anything like that.
 
N1120A said:
With an STEC30, especially if you have GPSS, the best thing to fly is an RNAV anyway - no "middle marker" or anything like that.
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I made the comment on what was in the manual, not how I fly. I find my AP flies ILS and RNAV both pretty well.

I did find that there’s an altitude limitation in the manual. Can’t use it above 28,000 ft. That’ll be a real problem for my Cherokee.
 
Hang 4 said:
Fair point. What is says "at middle maker, if missed approach declared, disconnect autopilot". Then a missed procedure. What I can't find is a "disconnect below X altitude". After all the conniption fits about using a trutrack below 700 ft agl, I was curious what the guidance was for mine. Aside from referencing a navaid that is disappearing, not a lot that I can find.
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Is there something that talks about “maximum altitude losses” in various phases of flight? While not limitations, these are an indicator of how fast the autopilot can go its own way with a malfunction. (It doesn’t actually malfunction worse enroute than on an approach...the numbers are based on different reaction times.)
 
the issue is trim.....once you hit that disconnect button, "red button", the aircraft will revert to the previous trimmed condition. You really don't want to be figuring this out at DH.
 
Checkout_my_Six said:
the issue is trim.....once you hit that disconnect button, "red button", the aircraft will revert to the previous trimmed condition. You really don't want to be figuring this out at DH.
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On a vertically guided approach the airplane should be in trim at DA provided the airspeed hasn't changed since GS intercept. At least that was the case with all the auto-pilots I flew (only a few in GA airplanes a long time ago).
 
aterpster said:
On a vertically guided approach the airplane should be in trim at DA provided the airspeed hasn't changed since GS intercept. At least that was the case with all the auto-pilots I flew (only a few in GA airplanes a long time ago).
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Depends on how many servos are installed. Some GA planes don't have a pitch trim servo, some do.
 
I can let the AP fly the plane from 200’ on the climb to DA thru a miss without touching the controls. I’ve been flying an experimental panel with GRT, TruTrak, G430w in an RV10 with that capability for 9 years. Took some tuning to get it to fly down to 200’ without excessive wing rocking.

With electric trim, the AP drives the pitch trim as required so discoing the AP leaves the plane trimmed as the AP left it.

In terms of flying the final approach, I tend to fly in 2 different modes.
1) When being vectored for an ILS, I may or may not use the AP to vector around but once cleared for the intercept, I press the necessary buttons but tend to hand fly the needles.
2) When cleared to a IAF of an RNAV, I usually let the AP fly the whole thing.

Hand flying requires maintaining a certain level of proficiency but so does flying the AP. Getting the buttonology right is critical as is getting out of any button lined potholes when you don’t get it right.




Sent from my iPad using Tapatalk Pro
 
Hang 4 said:
I made the comment on what was in the manual, not how I fly. I find my AP flies ILS and RNAV both pretty well.

I did find that there’s an altitude limitation in the manual. Can’t use it above 28,000 ft. That’ll be a real problem for my Cherokee.
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They fly an ILS ok, but you really have to get on the LOC before switching to TRK, or you end up paralleling it.

28000 is for RVSM. Not a lot of planes that go that high are going to have something as simple as an STEC30.

Checkout_my_Six said:
the issue is trim.....once you hit that disconnect button, "red button", the aircraft will revert to the previous trimmed condition. You really don't want to be figuring this out at DH.
Click to expand...

Not much of an issue with the STEC30. You have to trim the airplane anyway. It doesn't auto trim. If you are trimming to the speed category and VS needed, you'll be in a trim position that works.

asicer said:
Depends on how many servos are installed. Some GA planes don't have a pitch trim servo, some do.
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On this specific AP, the only pitch axis effect the AP has is to hold altitude, which also requires the pilot trim the plane according to what the AP needs.
 
As others have said, you need to know the limitations of your autopilot installation. It will have minimum engagement and disengagement altitudes. It will also have a pre-flight test procedure and non-normal procedures. Many GA pilots ignore these but, especially if you're using the A/P in IMC, you really should do and know them.

When flying IMC with an autopilot, you must maintain proficiency both with, and without, the autopilot. Trying to use an unfamiliar autopilot in a busy IMC situation can, and has, caused violations and accidents. If you are proficient with your autopilot it can be a great workload reducing tool.

Use the autopilot as a tool to manage your workload. Assuming you are already proficient, hand fly more when the weather is good and ATC workload is low. As the weather deteriorates and/or ATC workload increases, use the autopilot more to manage the workload and maintain situational awareness.

Practice de-automation strategies for situations where you need the airplane to respond quicker than you can program the automation or when there is confusion about what the autopilot is doing. i.e. drop from NAV to HDG while reprogramming a new clearance so that your turn on-course isn't delayed. Drop to HDG and V/S when the autopilot isn't doing what you expect so that you still have some help from the autopilot while you figure out what is wrong with the programing for the more advanced features. If everything is going wrong, click it all off and go back to hand flying to ensure that the aircraft is doing what you intend. etc.

1. Know the published limitations of your A/P
2. Perform the applicable pre-flight tests on your A/P
3. Know and practice the applicable non-normal procedures of your A/P
4. Include practice in flying procedures both with, and without, the A/P so that you're proficient using either method.
5. De-automate in stages, as needed, to ensure that aircraft control and adherence to ATC clearances in navigation and altitude are maintained.
 
Larry in TN said:
or when there is confusion about what the autopilot is doing. i.e. drop from NAV to HDG while reprogramming a new clearance so that your turn on-course isn't delayed.
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And, slew the heading cursor to present heading before going into HDG mode. With the good Garmin stuff, you can go to ROLL while sorting it out.
 
Once the workload has stabilized and I'm just going down the approach path I like to turn it off and follow the FD.. I become a meat-autopilot

Nothing worse than having to learn to fly again with an out of trim plane at minimums. I'm not sure why people like to take the AP to minimums. AP is a workload tool, not a pilot replacement. IMHO
 
Tantalum said:
Nothing worse than having to learn to fly again with an out of trim plane at minimums.
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trying to understand why the plane would be out of trim running on AP? if you are descending at known power, you are already on a stabilized approach, trimmed, no different than hand flying at that power setting and manually trimming for that airspeed.
 
WannFly said:
trying to understand why the plane would be out of trim running on AP? if you are descending at known power, you are already on a stabilized approach, trimmed, no different than hand flying at that power setting and manually trimming for that airspeed.
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That's a good point.. somehow I'm just emotionally "out of trim" .. you spend 5-10 seconds getting back into the groove, so to speak. Maybe I should have written it like that instead
 
Tantalum said:
That's a good point.. somehow I'm just emotionally "out of trim" .. you spend 5-10 seconds getting back into the groove, so to speak. Maybe I should have written it like that instead
Click to expand...
yah totally agree to get the feel of the plane up high and not at mins
 
Radar Contact said:
Mine is good to go on passing 200ft agl on departure and has to come off at 200 agl on arrival. Sometimes I do both but usually I hand fly a bit more. Depends on my mood and the Wx.
Click to expand...
And the airspace. Busy airspace where ATC may be giving me lots of vectors, course changes and freq changes and the AP is a big help.



Wayne
 
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