ILS approaches

[Ilyushin76]

Calling all experienced CFIs. Just a confusion that I incurred during research. During an ILS approach, some instructors taught me to maintain the glide path using the power only. Others taught me to use slight pitch adjustments as well.

What do I remember for my future sorties :confused::confused:?

[A320baby]

Surly you need to use both? Pitch and power come hand in hand.

[paco]

Power in the early stages, nose when it gets too twitchy (around the middle marker)

Phil

[SFI145]

Consider flying an ILS with the flight director coupled to it.
The only commands from the flight director will be pitch and roll to hold the ILS beam.
If you also have a thrust director you will also have commands to move the throttles/thrust levers to keep the speed.
If you have an auto-throttle you have only pitch commands to hold the glide-slope.
So whether you are 10 miles out or inside the OM or MM the procedure is exactly the same and not as paco expounds.
paco also states 'around the middle marker' but if you are anywhere near the middle marker you are very close to Cat 1 DH or DA and unless stabilized you should go-around.
Traditionally the middle marker was the CAT 1 decision altitude so the approach must be stabilized well before then.
Imagine flying an ILS and for various phases of the approach you used different techniques. It would be very difficult for your monitoring pilot (PM) to know what you were doing without an extensive briefing on unorthodox procedures.

[paco]

If the monitoring pilot is taught the same way there is no problem at all! That's the way I was taught by several well respected instrument instructors on fixed wing and later by an equally well respected instructor on helicopters. Get stabilised in a proper ROD with power first, then no more than 5-10 knots changes with attiitude, because power changes simply take too long in the later stages (and of course there are speed tolerances to observe). Tip: Once you get a good rate of descent going, don't ignore the humble VSI. It can be a very powerful instrument in this situation.

We are talking about manual flying here, not letting an idiot machine do the job. I never use autocouple - I can do a much better job myself, unless it has been programmed to anticipate the flight path instead of going through it and then try to get back, only to overshoot again, and so on, thus making everyone sick. The reason pitch commands are used is because it doesn't know any better.

Phil

[OhNoCB]

Golden advise with the VSI comment above. Keep vertical speed in your scan (and know what your VS should be! half the ground speed and add a zero and all that good stuff for 3 deg.) and you will already know what corrections to make before you deviate!

Pitch vs power for glideslope is long debated right from basic PPL level. At the end of the day if you adjust one you will have to adjust the other. if you are at vref and you get low and simply pitch up and do nothing else you're going to have a bad day.

Because of this I think the argument is a lot to do with how people look at it, since realistically they are doing both anyway. My personal 'view' is pitching for glideslope and power for speed. Maybe on certain types this would need adjusted but so far it's worked well for me on SEPs, piston twins, a turboprop and a jet.

[A320baby]

I wouldn't recommend relying on the VSI if your flying a steam gauge aircraft

[paco]

I find it works a treat if you have the power set right for the correct ROD.

phil

[bingofuel]

I wouldn't recommend relying on the VSI if your flying a steam gauge aircraft


Worked fine for me, in the days that pilots flew aeroplanes manually !

[A320baby]

Bingofuel

I hear what you are saying, But doesn't the VSI, say in a Warrior or similar have some sort of lag? If not then I stand corrected.

[bingofuel]

Yes an element of lag, but not really an issue with the small adjustments required on an ILS, larger aircraft had IVSI, instantaneous VSI gauges which did not suffer the same.

[A320baby]

Ok got it, Sorry i thought we was referring to Smaller aircraft

[Genghis the Engineer]

Calling all experienced CFIs. Just a confusion that I incurred during research. During an ILS approach, some instructors taught me to maintain the glide path using the power only. Others taught me to use slight pitch adjustments as well.

What do I remember for my future sorties :confused::confused:?

You can't separate them.

If you increase power in the majority of conventionally configured aeroplanes, the aircraft will pitch up, decreasing the trim speed, so you need more power.

Similarly, decrease power, speed will increase, so you need back stick pressure.


Most instrument instructors teach point and power - so pitch to set flightpath, then power for speed. It's a nominal pair of controls, in reality for everything you use both.

VFR, it's more common - but not universal, to use pitch for speed and power for flightpath. Personally this is how I mentally fly an ILS as well, but it's not the way I was taught, and in reality I'm using both.

Both methods work, but you'll basically never get away with only using one control, you always need both for good combined flightpath and speed control.

And you have to use the VSI as a reference for rate of descent - you're looking for a steady RoD whether it's a big or small aeroplane, so lag is only an issue if making sudden corrections, which you shouldn't normally be doing anyhow.

G

[RedBullGaveMeWings]

Attitude + Power = Performance

Now, where do you go from here? I am using both, so far so good.

[lasseb]

It doesn't matter what you do as long as you keep the airspeed the same.
For larger planes usually auto-throttle keeps the airspeed, so you can fly using pitch.
For light a/c its a better option to use power, as this will maintain the airspeed approx the same and just change the ROD and thereby the descend angle.

But you (almost always) need to make small pitch adjustments after a power change to get the aircraft stabilized in the new ROD. Otherwise it will start slow oscillation for a while.

Just pitching the nose (for light ac) is usually not a good idea, as it will change the airspeed. So even though your ROD will change, so will speed; and that will give you the same descend angle i.e. not getting you closer to the glidepath.

[Ilyushin76]

Thank you all for your replies. It is much clearer to me now. :)

[banjodrone]

I'm not a CFI but this is a very old question. The problem with trying to impart skills by teaching "methods" is that while they may work well for some people, others need a more insightful and intuitive understanding that allows them to explore the envelope a little bit. Some people have an innate understanding of the relationships between speed, mass, momentum, energy, force, pressure, work, power etc etc. They don't need to see it explained with equations on paper and they can see and "feel" it in action every day. Such people usually respond well to a guided exploration approach to learning piloting skills, as opposed to learning it "off by heart". The attitude vs airspeed debate has been going on for decades and it's problematic when you've trained with instructors from both camps. Most seasoned pilots settle on just the right combination of both.

[Bloated Stomach]

Pitch for attitude, power/thrust for speed.

[paco]

Except when power takes too long to react, so the only way to control speed is by attitude.

phil