Autopilot in IMC

[GRP]

I do very little IMC flight limiting it pretty much to the odd climb and descent to let me fly on top if conditions are favourable to that. I certainly don't go off with any intention of flying for long periods in the soup, or requiring an instrument procedure to land. I do go off and practice this stuff from time to time with an instructor to make sure I know what I'm doing, but the reality is that where possible I prefer to fly with a view out of the front window.

I'm in two minds however as to whether I should stick the aircraft on autopilot (I've only got a roll axis autopilot) on those occasions where I am going to go into cloud.

On the one hand, if you always stick on the autopilot it does make life a lot easier and mindful of the fact that killer number one seems to be loss of control in IMC, having the autopilot keep things straight is an attractive option. On the other hand.... if you don't fly it by hand from time to time then your proficiency should you need it sometime will inevitably suffer.

It seems in some way to come down to the question of whether you prefer to take the risk that your competence will let you down in IMC or whether you take the risk that the autopilot is going to let you down in IMC.

What do others think and do? I've not bothered with the autopilot up to now because I have been taking the view that I ought to use every moment when the view disappears to practice a bit more, but I'm slowly coming to the view that I should make more use of the autopilot when in real IMC and simply do more simulated practice with an instructor to keep proficient.

[Final 3 Greens]

GRP

I don't fly IMC, but I have used autopilots to quite an extent in VMC.

My first comment would be that they work fine, when they are working fine ... but sometimes need a little adjustment. One Cherokee used to fly a huge lazy orbit on HDG! This is okay in VMC, where you can see what is happening and correct, but what about IMC??

Also, you are going to have to adjust pitch and power manually.

The other issue is to consider how your autopilot works. Is it simply adding aileron in response to deviation from a HDG or NAV instrument. Do you know what would happen if you encounter turbulence? Would an oscillation develop that could cause secondary effects and threaten loss of control?

I don't know the ansawer to the second point, but I would suggest that anyone using an autopilot in IMC should be very much on top of hand flying/scanning.

Perhaps this is one to discuss with an instructor?

[khorne]

Flying in IMC can be very high workload. An autopilot reduces that workload consierably. If you think there is something wrong with it then get rid of it otherwise allow it to free up brain capacity that you can use for other tasks.

The previous post suggested asking an instructor. If you can find one that flys regularly in IMC on an autopilot then good luck to you. There are plenty of exceptions but the majority of instructors fly VFR in C152 type aircraft in their local area and can add very little to this kind of query.

[englishal]

There was an interesting article in the AOPA mag about autopilots in IMC and autopilot coupled approaches. The conclusion was that why not fly in IMC and shoot apporaches using the AP, but when using the AP, great care should be taken to monitor what is going on. Especially during the approach, the AP should be followed through and the pilot should be prepared for a disconnect at any time.

I've flown AP coupled approaches, and so long as the AP is working correctly, they're brilliant. (I reckon the one I was using would actually land the aircraft, follow the ILS in, then pull the throttle over the threshold and there you go autoland......not that I tried it of course ) GPS coupled AP approaches are the way forward.

Cheers
EA

[alphaalpha]

Autopilots in IMC?? My thoughts are:

First of all, know the performance of your autopilot and check it out on the ground.

Second, if flying only occasionally in IMC, use the autopilot as an 'emergency' back up to hand flying. This keeps your IMC up to scratch and currency is vital. Have the heading bug pre-set on your chosen heading, so if you have any sort of problem, you only have to engage the a/p in bug mode. Then if you need to turn, move the bug 20 degrees at a time and monitor all the usual instruments for problems. You could also do this in an emergency to fly an SRA or QGH approach, if you were not current and (oh dear!) caught in IMC. However, it really is only a 'get out of jail card.'

Third, if you are current in IMC flying, do use the autopilot. It helps enormously when you have to review charts/plates etc or consider a diversion, or even just note ATC instructions. Its a vital tool for IFR regulars in my opinion and leaves some brain free for situational awareness.

Fourth, I have an STech 20 autopilot (no altitude capture/hold). I am not personally familiar with three-axis types, but there have been a couple of fatal accidents in recent years, where the autopilot is believed to a have flown the a/c very out of trim. On disconnect, the forces required to maintain controlled flight are extreme and would be unexpected, so very, very dangerous. I would therefore be interested how regular IFR pilots with (single) 3-axis autopilots monitor that all is well. And then there is ice.....

Regards

[eyeinthesky]

I don't really see a problem with using the autopliot for the reasons already given (reduction in workload), provided you keep the scan going to monitor any deviations.

Most important, however, is making yourself THOROUGHLY familiar with its operation whilst still in VMC. You need to establish whether it wanders (many do in NAV mode and HDG is a better option) or whatever and what is the best way to engage it (establish attitude and set or set to establish attitude etc).

In addition, you need to explore all the possible failures and how to cope with them. For example, is it linked to an electric trim? If the trim runs away can you overpower it manually or pull a CB to regain control? Practice recovery from unusual attitudes under the hood so that if it does all go awry you stand a good chance of surviving the episode.

Autopilots help a lot, even if it is just the wing leveller that you describe, but you need to be aware of their limitations. There can be a tendency for you to get out of the loop if you don't pay attention, which leads to the 'What's it doing now?' type of scenario.

Don't neglect your hand-flying in IMC, however. The more you do of it, the easier it becomes, and you might find you don't even feel yourself needing the assistance of an autopilot.

[eyeinthesky]

Sorry for the similarity with Alphaalpha's post: it appeared whilst I was still typing mine .

[Final 3 Greens]

Khorne

I think that your post was quite negative in tone.

If you ask around a few flying clubs, you can usually find an instructor who flies regularly in IMC using autopilots.

They are known as airline pilots and it is surprising how many instruct due to their love of flying.

In the course of gaining their job, they have usually encountered a fair range of autopilots, and are well up to speed on the issues of using them.

[GRP]

>Don't neglect your hand-flying in IMC, however. The more you >do of it, the easier it becomes, and you might find you don't >even feel yourself needing the assistance of an autopilot.

This was the point of the question really. By using the autopilot in IMC you can't help but neglect your hand-flying! I did a fairly long trip a few weeks ago with an instructor - the whole 4 hours was flown by hand in fact with a fair amount of it in IMC. It was great for the confidence but fairly tiring. Had I used the autopilot though it would have been a much easier flight, but I'd have lost the opportunity to get some IMC hand-flying experience. Now, had I been alone or just with non-pilot passengers it would have probably been better all round had I just stuck the autopilot on (I've used it a lot in VMC and have a good idea how it will react - I prefer for example to fly it on track either by hand or just using the heading mode before engaging a NAV mode since you know it isn't going to be making turns when it feels like it. I also scan just as much with it on - not a lot else to do really!)

I guess the crux of the question is - should one use the autopilot generally and polish up on hand-flying skills from time to time in case of an autopilot problem? Or should one hand-fly in general and be ready to switch on the autopilot if a problem arises? I'm just starting to persuade myself from the latter to the former and start using it more often!

[QDMQDMQDM]

I flew on a Beech 1900 twin turboprop, run by a commuter airline in Maine last year. Their aircraft were not even equipped with autopilots as the chief pilot felt they detracted from situational awareness and all that jazz. Admittedly, though, two crew...

QDM

[Romeo Romeo]

I read a book a while ago which said that you should earn the right to put the autopilot on. Fly the first hour by hand then you've probably earned it. There's no point doing it all by hand because then you might end up fatigued when it comet to the hard part of the approach, but you don't want to end up relying on the autopilot to save you bacon - because it might pack up.

[GRP]

That's a very good idea! Quite like that! Best of both worlds.

The reason I came to asking this question was that I was flying on saturday with the family on board. I had to abandon the flight because there was lowish cloud around my departure airport, although I knew it was ok where I was going as I had just driven from that direction 15 minutes earlier. Shortly after take off it became evident that I was not going to get to where I wanted to go without climbing up into the cloud and either getting above it or bursting out into the clear air to the north. With the children on board (for the first time with both of them in there) I decided that discretion was the better part of valour and that we would drive to our destination. The children were quite excited to be in the aeroplane and I didn't want to find that I was being distracted at the same time as trying to concentrate on keeping the aircraft going in the right direction and right-side up!

The owner of the aircraft on hearing this asked why I had not just stuck on the autopilot and carried on climbing - and I've been wondering why myself since! Especially since when I drove it rapidly became evident that the conditions were as forecast and all would have been well!

[M14P]

as the chief pilot felt they detracted from situational awareness

Wow! There's a Chiefy who obviously does not understand what situational awareness is. Actually flying an aircraft is really quite a complex task for the brain to deal with (all give yourself a pat on the back for being clever chaps) and flying whilst using instruments and bouncing around in cloud is even harder. Just because you are steering doesn't mean you are situationally aware, in fact it probably means that you are FAR LESS aware than your monitoring crewmember.

Autopilots can be the biggest help or the biggest hinderence in the cockpit depending on the users understanding of the system (The "What's It Doing Now?" Phenomenon) and the capabilities of the system.

It is not a 'get me out of a sticky situation' tool. An autopilot does not allow you to fly beyond your capabilities it just allows you to use your time more effectively.

I have used very many different autopilots and therefore consider myself reasonably experienced on this matter:

More golden rules,

1. Seek Training
2. Understand the system
3. Treat 'George' as your second (or third) crewmember
4. If it does something that you are not expecting or do not understand TAKE OVER
5. Keep current with system use and integration

If anybody wants any training or advice on the subject I am happy to be contacted by my email

PS - GRP, I like you decision better than the owner's. The owner is suggesting that whilst he may not be capable of flying in cloud the AP is. That is a potential fatal reversal of priorities.

[Julian]

I have asked the same question of a few people (and from personal experience!) and the answer is almost always the same - yeah use it but keep an eye on it!

They do tend to do their own thing sometimes, a friend and I did a night flight back from Scotsdale, Arizona across the desert to Longbeach, California - not IMC but with no visual references it may as well be (if you have never done a lfight across a desert everyone should do - completely black! strange!!). We were using the AP on the long legs when we realise that it had gone into a shallow descent. The AP was doing nothing to correct this, we ended up disconnecting and retrimming the aircraft - after that we kept a close eye on it.

[Leclairage]

Hi GRP,
Catching up on an old post of yours here, but I am in a similar position....what say you we practise together? Your ship or mine?

[FlyingForFun]

I missed out on this thread last time round, probably because I didn't have an IR or IMC rating then. I do now, though, so here are my thoughts:

First of all, I would guess that asking an airline pilots what he does at work, as F3G suggested, might not be the best idea. Airline pilots fly on a very regular basis, and have more regular checks than IMC pilots. They are extremely current. Depending on the airline, they might well have the autopilot on for pretty much the whole flight - but they are current enough that they still retain the hand-flying skills (although haven spoken to some airline pilots about their colleagues - it's never them, always their colleauges! - maybe that's not actually the case!)

An autopilot achieves two things: it relieves the boredom of flying S+L on instruments for long periods, and it relieves the workload during the approach and the depature.

For the S+L segment, I say use the autopilot. It doesn't take a huge amount of practice to fly S+L and follow a VOR, but it is very tedious and therefore tiring, so get the autopilot to do it for you.

For approach and depature it's not so clear, because this is where occasional IMC flyers, IMHO, will very quickly loose currency if they always use the autopilot. Also (and this may not apply for a simple one-axis autopilot), if you never use the autopilot, you may find that you are not proficient in its use. When I first started flying an aircraft with a decent autopilot, I always used to hand-fly the depature up to cruising level, but after I while I'd discovered that I'd forgotten how to set a target altitude in the autopilot - not forgotten to the point that I couldn't do it, but it took a bit of mental capacity to remember.

I eventually settled on the following: on the basis that most IFR flights are going to be there-and-back, on the way there I would hand-fly the depature and use the autopilot for the arrival, and on the way back I would reverse it. Of course things never go to plan, and you will always find that when you plan to hand-fly an approach, you'll get to your destination, find it's CAVOK and end up doing a visual approach, so you need to be flexible to keep current at both methods.

Of course your experiences may well be different to mine!

FFF
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[IO540]

I tend to agree. Most private pilots don't get enough practice in IMC, including myself (and I do ~ 150hrs/year) so hand flying procedures is desirable.

However, the AP is there to reduce cockpit workload and that is the #1 safety feature in flying. I bet most pilots who made a fatal error would not have made it if they were not under pressure. Reading airliner accident reports makes that much clear. So many really stupid errors.

So if I was flying a very busy procedure I would go back to using the AP, including flying the ILS with it, to minima. Of course, one needs to practice how to do that too (fly an ILS with the AP), occassionally.

On long trips one spends most of one's time in VMC and a monkey can fly a plane in VMC, so then I use the AP 100%, disengaging it for the last 20-30nm of a VFR flight.

[DRJAD]

Interesting thoguhts.
To my mind, provided one is in current and fluent practice in IMC, then using the autopilot, even if single axis, is a good plan for phases of flight which are assisted by the equipment.
The reason for this is obvious - it is the diminution of effort which arises because the autopilot takes some of the workload.
However, what it does NOT remove from the pilot is the responsibility to maintain the monitoring (scan) of instruments in order to achieve the planned flight and to recognise abnormal situations.

[IO540]

However, what it does NOT remove from the pilot is the responsibility to maintain the monitoring (scan) of instruments in order to achieve the planned flight and to recognise abnormal situations.

You sound like a CAA "safety" sense leaflet

The use of an AP does exactly that: it frees up the pilot to keep an eye on everything, inside and outside. A pilot who is using an AP is much more likely to spot something going wrong.

[DRJAD]

Hmm, its just the way I speak and write!

What I meant is encapsulated in your comment, IO540.