Primary Instruments??

[GoneWest]

I've just read a photocopy of an instructors notes that says that the primary instrument for use in determining pitch attitude during straight and level flight is the altimeter.

This (apparently) came from an instructor handbook.

Can't say that I agree. Responses on a postcard......

[Angle of Attack]

Question? we cover all instruments except the altimeter? Could you accurately determine the pitch attitude of the aircraft? You might say if the altimeters climbing it would be a high nose attitude, or if its unwinding it could be a low nose attitude but the point is you could'nt tell me the attittude of the aircraft.

With the attitude indicator you can determine it anytime. I think you might find that when in straight and level flight, you set a pitch attitude and to confirm that this attitude is correct you scan the altimeter.

[BEagle]

Correct. The instrument used to confirm that pitch attitude is correct in S&L flight is the altimeter. The scan goes

LOOKOUT - for other traffic
ATTITUDE - having checked for other traffic, look at the picture formed by the outside horizon and whatever reference you have available; windscreen centre strut, canopy arch etc. Make sure that it's the picture you need.
INSTRUMENTS - check that the altimeter isn't moving, showing that you're in level flight, the ball is centered, showing that the aircraft is in balanced flight - and if you can't see anything outside to indicate that you're in straight flight, check that the DI isn't moving. If any of these instrument indications aren't what you want, then it's back to another LOOKOUT, then readjust the ATTITUDE and re-check the INSTRUMENTS...... This L-A-I sequence is the key to maintaining the attitude for any desired steady state of flight - climbing, descending, turning. The only difference being that other instruments are referred to in these other stages of flight - but the attitude indicator or artificial horizon is ONLY used in visual flight to confirm that the visual assessment is correct. So, if you wanted a 30 deg banked turn, during the L-A-I sequence of maintaining the turn, you should only look briefly at the AI/AH to confirm that you've selected 30 deg, not 20 or 40!!

[ 20 October 2001: Message edited by: BEagle ]

[DB6]

Depends if you're talking visual or instrument flight. In VMC then yes it would be the altimeter as you would be setting the pitch attitude using the visual picture - the AH should be largely redundant. In IMC then of course the artificial horizon/attitude indicator becomes the primary pitch reference and the altimeter becomes a performance (or confirmatory) instrument. Many VFR-only aircraft don't even have artificial horizons.

[ 20 October 2001: Message edited by: DB6 ]

[BEagle]

DB6 - the attitude indicator becomes the primary attitude reference in IMC - confirming that the AI/AH indication is correct is still achieved by scanning the relevant instrument.

IF intro - easiest pre-flight brief there is:-

"OK Bloggs - remember all that Lookout - Attitude - Instruments stuff we taught you way back? Well now you won't have to lookout (ATC will look after that) and you can imagine that the only view of the world outside that you're going to get is the little hole I've cut in the instrument panel - it's called an Artificial Horizon - everything else you'll do today will be by using exactly the same techniques which you've been using before in VMC. Questions? No? Why am I still looking at you - WALK!"

[DB6]

Quite so, BEagle (OK perhaps I should have said primary pitch attitude reference) but the original post talks about determining pitch attitude, not confirming, which would require a control, not a performance, instrument. Or at least that's the way I took it, I could be wrong. I think fundamentally we are in agreement.

[ 20 October 2001: Message edited by: DB6 ]

[BEagle]

Yes - I think we are. But then there are aircraft around like the Quickie Q 200 with its incidence adjuster which allows you to fly straight and level at the same airspeed but at different attitudes and power settings..........very b£oody confusing!!

[Another CFI]

According to the correct answers for the FAA instrument rating examination the primary instruments in straight and level flight are:-

Primary pitch - Altimeter
Primary bank - Heading indicator
Primary power - Airspeed indicator

and for pitch and bank the Attitude Indicator is considered to be a supporting instrument.

[Chuck Ellsworth]

Instrument flying is really no different than visual flying except that when flying on instruments alone you are just shrinking the visual clues into a smaller picture.

It may help to rid your mind of thinking about control instruments and preformance instruments as well as primary and secondary instruments and just think of the flight instruments as one picture.

When I fly with reference to the instruments I do not "scan" so to speak, what my mind computes it the whole picture that it receives no matter where on the panel my eyes are focused. Peripheral vision will also give you clues to any diversion from the desired attitude. ( Probably the most important item for smooth accurate isnst. flying is proper use of trim.)

For instance whan flying straight and level at 3,000 feet or 30,000 feet if the altimiter needle shows 3,200 or 30,200 feet peripheral vision will alert you to the diversion.

We can get to involved in explinations and descriptive wording and make something relatively easy difficult.

Bear in mind I am referring to steam guages, the glass cockpit is another subject.

The longer you do it the easier it becomes, so try and make the learning process easy by using the least amount of wording to get the lesson taught.


P.S.

I am doing a ferry costing for a new customer, could one of you Brits give me the price of 100LL in the U.K.? Liters & pounds will be fine.
Thanks
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:D The hardest thing about flying is knowing when to say no. :D

[moggie]

Does the question not hinge upon whether you are discussing the primary instrument for CONTROLLING pitch atttiude or the primary instrument for assessing pitch PERFORMANCE?

The altimeter can not tell you what pitch attitude you have other than to tell you if it is: 1) right 2) too high or 3) too low.

By the way - are we really going to use the FAA as the definitive source of all that is right with technical questions? Hope not!

[GoneWest]

<<<The altimeter can not tell you what pitch attitude you have other than to tell you if it is: 1) right 2) too high or 3) too low.>>>

How does that work then - when stalling in IMC?

Nose high and a descent on the ALT.

edited for <<< and >>> marks that were missed out of the cut and paste.

[ 26 October 2001: Message edited by: GoneWest ]

[BEagle]

Gonewest - that is an extreme case for which Unusual Attitude recovery action should be taken.

moggie explains it exactly; you select what you anticipate to be the correct pitch attitude on the AH, hold it, trim it. Then you assess whether it is the correct attitude by reference to the effect on the altimeter. If it shows a climb or descent you adjust the attitude in the appropriate direction by reference to the AH and retrim, repeating as oft as ye shall have need!

I share his comments regarding FAA guidance.......

[Another CFI]

Even though I made the original post about the FAA viewpoint I agree that we should not necessarily take their viewpoint, or anyone else’s as definitive. The main reason for making the post was to show that there are differing views on the “correct” answer.

I believe that we make life too complicated for students by concentrating on the difference between primary and secondary instruments and also between control and performance instruments. Surely the most important thing is the totality of information that can be gained from the combination of all of the instruments. At the initial stages of teaching instrument flying the student is taught to scan the instruments since they require some basis for instrument flying but I concur with Cat Driver that once we gain experience we subconsciously assimilate information from the instruments rather than formally scanning them.

When teaching IMC students I find it interesting to note the improvement in the student’s full panel flying after they have been taught limited/partial panel flying. I suspect that this arises because the student is starting ,at least to a small degree, to assimilate the data that is being provided by all of the instruments and is using that data to achieve the desired result rather than slavishly following a rigid scan.

[Chuck Ellsworth]

Thanks , Another CFI.,, Your comments are exactly what I have been trying to point out for years.

Flight training has been taken over by the lets make up a new acronymn crowd who sit in dark corners and dream up nifty sounding new explinations and unneccesary thought patterns to make what was straightfoward difficult.

Add to that some of the goofy new ideas on how to fly two crew airplanes and we have to thank God that the airplane designers are turning out smart airplanes to save us from the dumb flying techniques of some of the pilots that I observe sharing the airspace with us.

Back to inst. flying. When I trained for my commercial license we had to demonstrate needle, ball & airspeed recovery from unusual attitudes. Once learned it made the transition to instrument flying much easier.

Having to much information crammed into any learning process will accomplish two things. Extend the learning time frame and dumb down the end product due to not fully understanding the basics.

There all you guys and gals have a go at me and show me the error of my ways :) :)

.............................................

:D The hardest thing about flying is knowing when to say no. :D

[moggie]

Another CFI and Cat Driver - I whole heartedly agree with you. One thing I find is that after covering NDB approaches on the course, trainees fly better ILS approaches. I believe that this is because you can only successfully fly Non-precision approaches using good attitde, speed, ROD and power control but you can needle chase an ILS and get away with it (most of the time).

I rarely find myself using the kind of scan I was taught on BFT in the RAF (Artificial Horizon - Altimeter - AH - Speed - AH - Heading - AH etc etc.) I now find a roving scan bringing in periferal instrumentation shows uperrors more quickly. However, you do have to start somewhere and a rigid, mechanical scan gets you on the way).

I am also amazed at how little some of the flying schools actually teach the cadet pilots. One school (no names but based in Bedford) used to send out airline sponsored cadets who had never flown a SID or STAR and maybe one or two procedural ILS approaches - i.e. just enough to scrape an IR and let someone else do the remedial work. That same school now no longer trains for BA after getting found out!