Why must I have a slip and turn indicator?

[Flying Ted]

I'm currently studying up for my CPI. Today we were discussing the minimum equipment requirements as per CAO 20.18.

Appendix 1 tells me in need an air speed indicator, altimeter, compass and as accurate time piece for PPL flights. If it is charter flight I need to add a turn and slip indicator and outside air temperate indicator.

Can any one tell why I need a slip and turn indicator? All the other items make a lot of sense to ensure a safe flight but I can't see why the logic behind the slip an turn.

[Jack Ranga]

Just in case you are turning or slipping & don't know about it :ok:

[VH-XXX]

Why must I have a slip and turn indicator?

So when you inadvertantly enter cloud you will be able to do a coordinated 1 (or 2) minute turn back to where you came from.

Typically in an *old school* configuration, eg 90% of Cessna's, T&B / T&S indicators are powered electrically to go with the vacuum powered AH & DG to give you a level of redundancy in the event of an engine or vacuum pump failure. A *good* pilot could happily fly through cloud on the T&B in the event of an AH failure.

[Ixixly]

As XXX said, redundancy is why. Private Flight if you decide to not have one or fly with it Inop then that's your prerogative and you're life that gets put at additional risk if something should go horribly wrong, but in a commercial environment it would be considered unacceptable to not have such a simple and basic piece of equipment not installed and working, admittedly though they are a lot more expensive than I had imagined!!

[Centaurus]

A *good* pilot could happily fly through cloud on the T&B in the event of an AH failure.

"Happily?" I realise you have inverted commas the good bit to make your point, but believe me it wouldn't matter how good you were. Any pilot would be in dead serious trouble if he lost the AH and had to fall back on the Turn Coordinator or the Turn and bank indicator. Unless of course he was current in the last few weeks on limited panel flying in IMC both in a real aircraft or synthetic trainer. Readers may recall from about ten years ago, a Mooney (?) flying near Mildura (?) at night lost his AH and decided to turn back towards Mildura and land. With only a Turn and Bank indicator he didn't last long and crashed after coming apart out of control.

Reminded me of a quiet event when a 150 hour student with his own Cirrus was practicing instrument flying in a synthetic trainer called, I think, an Elite flight trainer. The student was happily doing several practice holding patterns. The suggestion was made that it might be worthwhile practicing flying without an AH in case one night the AH fell over. The student said it would never happen in his EFIS Cirrus so no need to make it hard for himself.

After about the fifth holding pattern with the student congratulating himself how good he could fly on instruments, someone passing by the Elite trainer, quietly failed the AH. It took less than one minute before the student was in a screaming spiral dive cursing the poor old Elite trainer. Nothing wrong with the synthetic trainer apart from the failed AH. The problem was the cocky pilot. Even after that rather dramatic ending he still refused to practice limited panel on instruments. Last I heard of him was that he was a flying instructor teaching instrument flying...:rolleyes:

[Flying Ted]

So I thought the requirement could be in case of inadvertently entering IMC. But as Centaurus says if that happens I'd really want a AH rather than a S&TI. Its interesting that AH is not required as part of the minimum equipment requirement.

[VH-XXX]

Caught up with an old instructor of mine recently and he was telling me that he braved IMC on an electric T&B for over 30 mins. He had get-there-itis but the added bonus of definitively knowing he wasn't going to hit anything. Braver than I. Certainly a good skill to practice if you are bored on a cross country flight one day.

[VH-XXX]

Nah, has got the skills to pull it off safely, just probably shouldn't have done it.

There's plenty of pilots out there that have done it with no instruments other than ASI, ALT and perhaps a VSI. One of those pilots I know lost the roof off his aircraft whilst doing it :uhoh: so not always a happy ending :ok:

[Centaurus]

If you think it would never happen to you, then how about this. En-route Townsville to Darwin in a Lincoln bomber in the 1950's, the AH toppled terminally leaving the pilot flying at night with primary panel only - meaning the Turn and Bank indicator. This happened at the half-way point with three hours to go. Due seasonal weather aircraft in cloud most of the way but when not in cloud was black night IMC. The aircraft arrived over Darwin about one hour before dawn. Rather than risk an instrument let down on the Turn and Bank indicator, the pilot elected to fly within a 20 mile radius of the airport until as the sun came up he could see holes in the cloud. He then let down through the holes until visual with the ground and airport.

[clark y]

Another thing to remember about a failed AH is that it may fail slowly (not too sure about EFIS AHs in lighties) and may not be picked up until you are already in a spiral. Also have something to cover up a failed AH because seeing it sitting on some weird angle or spinning around is a rather large distraction while flying limited panel.

[Oktas8]

It's interesting that AH is not required as part of the minimum equipment requirement.

A basic AH is vacuum powered, and therefore has no prominent failure flag. The "failed suction pump" indication is likely to be well outside the primary scan area.

That's one reason why why the law requires, at minimum, some sort of turn indicator. Being electrically powered, the failure indicator is more prominent.

[T28D]

Why do you need a T & B simple really if all else fails it can save you and your passengers lives.


No more complicated than that !!!!!!!


Practice flying limited panel T & B, ASI, Altimeter and ROC it is very rewarding to get it right and the blue is on top and the aircraft stays straight and level.

[uncle8]

Isn't the T & B properly called a Turn and Balance rather than Turn and Bank?

[Brian Abraham]

Was a time when flight in IMC was being undertaken without the benefit of attitude indicators. Charles Lindberghs Spirit of St. Louis contained nothing but fuel pressure, oil pressure and temperature gauges, a clock, altimeter, tachometer, airspeed indicator, bank and turn indicator, and liquid magnetic compass.

Kingsford-Smiths Southern Cross also had a similar level of basic instrumentation.

[Wally Mk2]

'uncle8' It's mostly known or called a Turn & Bank indicator by the Yanks but I believe it's a Turn & Balance indicator meaning if the ball is centered & the bat (if it's a ball & bat unit) is lined up with the offset ref mark then yr turning correctly/balanced at a rate one turn.
At the end of the day they mean one of the same thing when the term 'T&B' has been written.
Used to reg use the T&B on many an IFR renewal.

Wmk2

[Flying Ted]

The CAO refers to a Slip and Turn Indicator. It would seem "Slip" and "Balance" are interchangable.

Thanks for all the posts so far.

If I can summarise, the additional requirements for Charter operation is in case of inadvertent IF. The regs specify a S&T rather than AH because either:
> Thats all Kingford-Smith had so it should be good enough for the rest of us or
> Electrically power instruments are more reliable than vacuum indicators (that is why T&B rather than AH)

Is that a fair summary?

By the way I'm not sure what a ROC is. Rate of Change indicator? Is this same as a VSI?

[T28D]

Back in 1960 when I was a RAAF Apprentice Instrument Fitter ROC was Rate of Climb and post the WW II the rate gyro was always referred to as a Turn and Bank.


What would the RAAF know ?????

[scroogee]

You may also find the rules allow for a second AH (electrically drive if the primary is vacuum driven) so long as there is a balance ball incorporated somewhere, in lieu of the T&S. It might also need a greater degree of pitch freedom than the primary as well (all this based on an un-researched memory of NZ rules).

[VH-XXX]

What would the RAAF know ?????


The RAAF lost all credibility in my mind when they couldn't land their 737 at Lorde Howe (and returned home) and Virgin? landed shortly after.

[UnderneathTheRadar]

Charter operation is in case of inadvertent IF.

Not quite. You can be legitimate IFR and lose your AH. You can be inadvertent IMC but use your AH.

[Ixixly]

I'm assuming you're reply with the summary was meant to be totally flippant, either that or you really didn't get much out of what was posted here as you were expecting people to agree with some other point perhaps "There is no reason, it's ridiculous" possibly to backup some ridiculous argument you've had, otherwise why else ask here instead of asking the people you are studying with and/or people you're paying to train you.

You're going to make an excellent Pilot mate.

[Flying Ted]

I'm assuming you're reply with the summary was meant to be totally flippant

Not totally flippant but certainly tongue in check. Yes, the question arouse from a discussion at the flight school. Collectively we couldn't find any compelling logic for a) the extra requirements for charter work and b) assuming the logic is a guard against inadvertent IMC, why the T&S rather than AH. (You would have to be very unlucky to enter IMC just as your vacuum packs it in.)

I my view, none of answers so far have really nailed why the regs are they are. The closest answer I can surmise is that the requirement goes back to days of K-S when T&S indicators were more common/affordable than AHs.

[morno]

Perhaps more to enable some of the older aircraft around the traps that didn't have things such as AH's, to still be able to perform day VFR charter.

morno

[Ixixly]

You're probably right to a certain degree. It's possible those Regs were designed around a time when it may not have been possible to have an Electric AH that was reliable enough, perhaps these days it may even be possible to get an exemption to replace your T+B with an Electronic AH but I can't really see the reasoning, being an electrically driven mechanical device that would most likely have to be permanently activated with the aircraft electronics, in the event of an alternator failure, would this be an unacceptable extra drain on the battery compared to a T+B?

The other reason is that the T+B would be, IMHO, superior to the AH in the event of your Primary AH becoming U/S for the exact reason that others have mentioned that you can execute a pretty damned perfect 180 with just the T+B and your Watch which is not as easy to do with the AH. If you're in the soup and the AH goes then presumably your DG is also going to be gone as well and trying to use the damned Mag Compass when underpressure and with it bouncing around does not sound as appealing to me as starting a turn on the top of the minute then rolling out when it gets back to the top of my watch!

A T+B also has the upside of being able to keep your aircraft in balance which an AH doesn't do which is for passenger comfort and generally speaking I've had enough AHs start to go a bit wonky on me but I can't say I have ever seen a T+B that wasn't dead on accurate.

In a twin engine as well, in the event of an engine failure, it is far easier to just step on the damned ball and get it centered to correct for the yaw.

You'll also find that just about every aircraft has one installed, infact I've personally never flown an aircraft that didn't, so why bother to rewrite regs just for the option of removing something that everyone already has, I can't see why you would remove it and bringing back to my earlier point I've never seen one fail so I'd presume they last a really really long time and hardly ever require replacement so if it ain't broken, don't fix it!

Same goes for the regulations, if there was something better out there to replace it with and the industry was clamouring for it then they might look at it, but as the point has probably never been raised and there is apparently no problem to fix, why fix/fiddle with a regulation that isn't broken?

[Flying Ted]

Thanks Ixixly. However, my point is that the regs say that for VFR I'm not required to have AH just a T&S (plus the other primaries). So the answer is not in case my primary AH fails.

I have considered passenger comfort as a possible answer but the same rules applies to Airwork without passengers.

Also, I'm not suggesting anyone remove any equipment. My question is no more than an attempt to understand the reasoning behind the regulations. (Notwithstanding many of comments on this forum, I believe that most of requirements we have are for good, if sometimes obscure, reason. Naive perhaps.)

[Grogmonster]

xxx,

I am thinking you mean Norfolk Island. Lord Howe in a 737 would be something Special !!!!!

Groggy

[Hugh Jarse]

The RAAF lost all credibility in my mind when they couldn't land their 737 at Lorde Howe (and returned home) and Virgin? landed shortly after.
A 737 at Lord Howe?

I'd love to see that :}

[VH-XXX]

Geographically challenged is the word ! Give me a break, the are both islands and in the middle of the same ocean :ok:

Norfolk does sound better ;)

[Ixixly]

I see your point, in that case it comes down to Inadvertent entry into IMC, in which case having an AH is less critical than having a T+B, as we're all taught if you enter into Inadvertent IMC then you make a 180degree turn back onto a reciprocal heading, this is done by making a rate one turn which is indicated by your T+B but not on your AH (Yes, I know you can work it out but really that's the last thing you want to be doing).

Basically for VFR Flight you shouldn't 'require' an AH for a normal flight as you are "Visual" so therefore having a regulation that requires you to have an instrument that isn't required for your normal flight wouldn't be right, but should you enter into Inadvertent IMC then you require a means of getting back out of it which is why you use your T+B to turn around not an AH. So therefore you don't REQUIRE an instrument to make a flight Visual but you DO REQUIRE an instrument to get you back to Visual.

[Oktas8]

I believe TC type instruments (tied gyros in general) are less susceptible to failure than AH instruments (earth gyros), and are designed to make it easy to detect a failure when it does occur. We've all flown VFR with slightly wobbly AH's, but hopefully less often just ignored a flagged TC or T&S.

Ted, I'm not sure you're considering the two main implications here. Disregard the odds of the instrument failing just as you enter IMC, and consider:

- It is cheaper to maintain a TC over the long term, than an AH, and

- A pilot is more likely to detect (and have repaired) a failed gyro straight away if it has a simple failure flag on it, as opposed to being a little wobbly at times.

One is important to the operator, and the other to the regulator. Current law covers both bases.

In terms of safety, once in IMC, an AH is safer than a TC. Difficult to argue otherwise I think Ixixly...

[Ixixly]

Oktas8 Agreed on the failure likelihood of AH vs T+B, my comments in regard to the use of either AH or T+B in IMC were only meant to be taken in regards to the situation of a VFR Aircraft inadvertently entering IMC and having to turn around safely onto a reciprocal track to return to VMC with a Rate 1 turn onto a reciprocal track being easily achieved with a T+B and your watch.

Of course it can also be done on the AH at an acceptable Bank Angle and using the DG but I'd probably trust the T+B more than an AH which isn't necessarily designed, tested or maintained to an IFR standard and is known to be a bit askew, plus if you rely on the AH and it isn't quite up to scratch like you thought then you might find yourself trying to maintain a turn on the AH which is actually based upon an AH that is toppling without you realising leading to far bigger problems.

[Arnold E]

A basic AH is vacuum powered,

Or pressure, ofcourse.:ok:

[MakeItHappenCaptain]

Not on the co-pilot's side of a Caravan, or CT4....:E:ok:

[Square Bear]

this is done by making a rate one turn which is indicated by your T+B but not on your AH (Yes, I know you can work it out but really that's the last thing you want to be doing).


TAS/10 + 7 is accurate enough, and that's not very hard.

IMHO to preference the T&B over an AH in IMC would be madness.

Anyway, the concept is to scan all the instruments and process all the information.

[Ixixly]

So now you're sitting there as a VFR Pilot who has inadvertently entered IMC thinking "S**t, S**t, S**t, I need to get out of here, umm, ok, turn onto reciprocal heading ummm...TAS is ummm... I'm going 120kts i'm at 2500ft so take that, divide by 1000, 2.5, times that by 2 ...no wait, 4, no 5 that's right, damn, haven't done this in a while... ok so that is 12.5 add that to 120 so about 132, now divide that by 10...umm... 13 add 7, 20 degrees, ok, damn, there is no 20 degree marking on my AH, just 15, 30, 45, ok, so just 15 plus a little extra I guess...sure, that looks about right...ok, now time it for the next minute..." Theres an extra 30 seconds worth of IMC you now have to turn back around and get out of so an extra minute assuming you were pretty accurate in your working out and got your heading correct and aren't heading out further into muck, that's a fair whack of your 178seconds CASA reckons you have left to live!

Or, I could go ""S**t, S**t, S**t, I need to get out of here, umm, ok, rate one turn, ok, now time it for the next minute..."

Now you tell me which of those 2 scenarios looks easier? Once again remembering that you're in IMC in a VFR Aircraft relying on an AH you don't really spend a lot of time paying attention to assuming that it's working correctly and isn't slowly toppling sending you into a spiral dive or isn't a bit lazy meaning you roll out at say 160degrees instead of 180, and yes you have you're DG and you can compare to that but once again you'd need to correct it because if it's like most DGs out there it's probably gone out by a reasonable amount during the turn and if you're in IMC you're stupid little Mag Compass is now bouncing around making it harder to get an accurate reading to reset your DG....

That T+B, if it's working, it's working, end of story. Getting out of IMC in a VFR Aircraft that'd be what I would teach someone to do and it's what I was taught to do as well, the AH becomes your backup to confirm, not the other way around. Plus teaching a VFR Pilot they'll be better off using the AH could lead them to a false thought of "Well, I'm already in it and I can use this AH so I'll just continue on" instead of "Nope, never really been advised to use AH before, not comfortable with that, I'll just got with the T+B to turn around and get the hell out!"

Yeah, I know, I'm looking at worst case scenarios but I'd rather assume the worst and be pleasantly surprised than the other way around!

[T28D]

caravan and Ct4 have co pilots ??????


Not on the co-pilot's side of a Caravan, or CT4....http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/evil.gifhttp://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif

[ShyTorque]

this is done by making a rate one turn which is indicated by your T+B but not on your AH (Yes, I know you can work it out but really that's the last thing you want to be doing).

But any aircraft can turn at rates other than Rate 1 and still safely do a 180! ;)

During our RAF jet training we used to have to practice limited panel instrument recoveries from UPs, using the T&S after the AH had been toppled, as it is likely to do if you got the aircraft totally out of kilter, for example during aerobatics, or instrument failure and (very) slow scan....

The limitation of the instrument was that if you were pulling 'G' it greatly over-read. So you had to unload to 1G before using it. The advantage was that as it worked using a caged gyro it couldn't be totally toppled.

Speed (control),
G, (unload to 1 on the G meter)
Roll (opposite direction until the turn needle comes off the stop, then smartly centralise the ailerons),
Pull (stop the altimeter unwinding),
Repeat as necessary... Still rings a bell.

[Square Bear]

Ixixly

If you could advise how to accurately get attitude from a T&B ....

IMO, in your scenarios' relying solely on a T&B would mean that you wont use much of your "178 seconds that CASA reckons you have to live"

Really, using an AH is not as complicated as you are making it out be.

[Centaurus]

Nope, never really been advised to use AH before

That would suggest the instructor who was responsible for the student pilot's ab-initio training, needs to be retrained himself; since understanding the use of the artificial horizon as an aid to both visual and IMC flight should be part of straight and level flight, climbing and descending.

[Ixixly]

I capitulate, I am grasping at straws there and pulling crap outta my arse!! You guys are correct that the AH is of course a better instrument in IMC conditions in an IFR Aircraft and possibly in a VFR Aircraft assuming the Pilots do keep an eye on them on a day to day basis and recognise when they are not performing well enough to be relied upon. But honestly I'd still rather use the T+B to get myself into a nice rate one to get back to VMC rather than the AH and use the AH as a backup to check I'm not climbing or descending, I shouldn't advocate it's sole use in such a situation this would be ignoring a perfectly valid source of information as Square Bear pointed out.

I should point out that was my point Square Bear, if you only have 178 seconds to live then you don't want to be using anymore of that than you have to.

[Tankengine]

It's all just historic, T&Bs were electric, AHs were pneumatic.:rolleyes:

The rules on instruments are very old, don't expect the department of hanging names to keep up.:hmm: ( or manufacturers):ugh:

[Brian Abraham]

T@B were once pneumatic as well Tanky, very few GA aircraft having electrics in the 50s, 60s, powered by a venturi stuck out in the breeze.

The T@B has its uses over and above an AH. Clem Atkins at the RVAC in the 60s used to teach spin recovery under the hood in Chipmunks using the T@B, the AH would have toppled during the gyrations, so of no use. Do people practice partial panel these days?

[Ixixly]

Which Aircraft is that from?

[scavenger]

Sorry Ixixly, I have to call you on this. The OP asked a series of simple questions and you reply with:

You're going to make an excellent Pilot mate.

in a smart ass way.

Then you carry on with garbage about the TC being preferable to an AH because you can fly a balanced rate one turn. How about pitch attitude? What do you think the chances are of someone who can't fly something approximating a rate one turn on an AH maintaining level flight on limited panel? Hey, at least the spiral dive would be balanced.

I understand the name turn and bank indicator is sometimes used but really is a misnomer because the thing doesn't indicate bank. A turn indicator indicates rate of turn. A turn co-ordinator indicates rate or turn and rate of roll (due offset gyro axis) but neither directly display roll or pitch attitude.

Agree that the rule is there for inadvertent VFR into IMC and really is outdated. When the thing was written, aeroplanes had turn indicators more than AHs.

[Ixixly]

As I mentioned Scavenger, that comment was made in relation to a VFR Aircraft entering into Inadvertent IMC and executing a turn back onto a reciprocal track, I never meant you should ignore the AH or your other instruments, at no point did I say "Hey, just go ahead and ignore everything else sitting in that cockpit and use only your T+B and your Watch". At no point did I say that a T+B was totally superior to an AH, I talked about situations in which it may be preferable so don't go putting words into my mouth or my posts.

[Square Bear]

Interesting no mention of the AI...

Neither does it mention scanning the other instruments, such as the VSI and ASI, HSI or engine power indicator...that doesn't mean you wouldn't use them.

The CASA issued VFR (Day) syllabus - Aeroplanes:

GFPT requires 2 hours of IF using the full panel
The PVT Licence requires 2 hours of IF using the full panel

Full panel is "Flight instrument array of at least an Artificial Horizon (AH), stabilised Heading Indicator, an Air Speed Indicator (ASI), Vertical Speed Indicator, Altimeter, Turn and Balance Indicator/Turn Co-ordinator and an engine power indicator.

Ixxily, what you are suggesting is Limited Panel, and that only gets around 2 hours out of 10 hours in the CPLA training. A private pilot is not even required to have completed Limited Panel..

. Plus teaching a VFR Pilot they'll be better off using the AH could lead them to a false thought of "Well, I'm already in it and I can use this AH so I'll just continue on"

If they hold a CPL they will have completed 14 hours of IF training, 12 using the AH.

At PPL level they will have completed 4 hours using the AH.

And no, I wasn't advocating ignoring a perfectly valid source of information, that seemed to your point.

What I was advocating was that the primary information source should be the AH with the other instruments as supportive.

And that is how I taught the sequences in Restricted/GFPT, Unrestricted/PPL, CPL and CIR and how the syllabus was written for it to be taught.

Anyway, do it how you want to, its your 178 seconds, not mine.

[tecman]

Interesting thread. Prompted me to wonder if the current PPL Night Rating insists on any additional partial panel training. As far as I can see from the CASA syllabus, it doesn't. When I did a night rating (Class IV inst) a long time ago, I recall practicing flying and UA recovery using only the (electric) TC, ASI, altimeter and compass. Not sure if this was then a requirement, or a local enhancement. The scenario of dread was, of course, a vac pump failure on a pitch black night, taking out the DG and AH.

Don't know if there are any of those Venturi systems mentioned by Brian A. still out there but even as a student it struck me that you'd have to be a bit of an optimist to blast off NVFR with that system. I guess there was no vac pump to fail but hurtling down the strip on a dark night, un-caging the gyro, and hoping it all worked seemed a bit optimistic. I have no doubt, though, that there are plenty of folks here who managed it well on a routine basis!

[lilflyboy262...2]

Pitch control.... Well you have an ASI,VSI and Altimeter...
Or people only capable of using one instrument these days?

How about something that is much more simple. The AH is not required in VFR flight.
T&B can be used for co-ordination in turns, engine failure in multi-engine, some spin stuff, rate of turn, and recovery from the emergency situations noted before.

An AH is just an instrument that helps co-ordinate all the above information and the picture outside the plane into one place. If that fails, you still have all the information from other sources.

Planning IFR, sure. I use the AH as my primary instrument.
VFR, I barely use it. But I still use the balance ball.

[Square Bear]

lilyflyboy262...2

you may have missed the point ........ the discussion (well the last page or so of the thread that some of us have managed to hijack..sorry OP :) ) relates to getting out of inadvertent IMC and back into VMC.

That is not VFR flying, that is IFR flying and if done by a non IFR rated pilot is extremely life threatening.

That pilot will need all the assistance at hand and to suggest that a non rated pilot could simply use just the T&B, ASI, VSI and Altimeter (and the watch for the timing!!!) to get out of dodge is quite a stretch.

The AH every time will contribute more to saving said VFR inadvertent IMC pilots life than to scanning a T&B, ASI, VSI, ALT and watch and using the AH as a backup device.

You state:
An AH is just an instrument that helps co-ordinate all the above information and the picture outside the plane into one place

Well said, however I take issue with the word "just", it does belittle the AH somewhat.

Anyway, if one is a current IFR pilot, agreed, flying limited panel is quite doable, but for this non hero, it would be very taxing and tiring.

Anyway...what is that about old and bold pilots :).

Cheers

[lilflyboy262...2]

I got what you guys were talking about.

What I was getting at was two points.

1) In that event of inadvertent IMC, and the AH fails, you have multiple other sources that give you the same information that the AH gives you, but just in a different format. The T&B is going to give you information that is needed for co-ordinated flight and can help you get out of the inadvertent IMC a lot faster.

In IFR/IMC, the AH is an amazing luxury to have, but it is not essential to safe flight. It is beneficial to increasing the overall safety of said flight though.

2) And more at the OPs original point.
In the VFR charter world, the T&B is used a heck of a lot more than the AH as you have visual reference with the outside world. This outside reference gives you all the information that is presented on the AH.
Information from the T&B is not readily available from other means, and is used in other situations outside of IMC.
The reason for the T&B indicator is not purely for an inadvertent IMC encounter as I pointed out in the previous post.

Personally, I would have the AH if it was functioning properly and just either climb or descend and ask for radar vectors out of there. Or just do a very rough compass turn until pointing roughly 180 degrees.... but thats just me. Using just a T&B is a heck of a lot of work. But I go back to point 2. The whole reason it is there is not for us to go bombing through bravely into ****e weather that ends with us IMC. But for the VFR pilot to use it in a raft of other situations....