Below GS on ILS

Richard

Richard

Final Approach
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Ack...city life
You're flying an ILS in the plane you most often fly. Inside the OM you notice you begin to dip below the GS. Do you make no adjustment to power settings as you roll in some up elevator trim or do you increase power settings?
 
Seriously, I haven't heard my marker beacon receiver go off in a long time.

But back to the question at hand. I add a touch of power, and arrest the sink rate until I am on GS again.
 
Not a trick question. I wanted to make the question as vague as possible to avoid 'loading' the question with specifics, ie, RPM, airspeed, etc. Think of it as an overhead type question.

I mentioned the OM so most would actually know where they are on the approach. I suppose I could have said final segment.
 
Richard said:
Not a trick question. I wanted to make the question as vague as possible to avoid 'loading' the question with specifics, ie, RPM, airspeed, etc. Think of it as an overhead type question.
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OK. Do what is necessary to stay on the GS at the proper speed. :aureola:
 
Hey Pete,

You do know you have to be somewhat in the vicinity of, preferably over, the beacon to hear it....LOL..:)



vontresc said:
Seriously, I haven't heard my marker beacon receiver go off in a long time.

But back to the question at hand. I add a touch of power, and arrest the sink rate until I am on GS again.
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Depends on how far below the GS I was. If I was not far I'd be more inclined to just use the yoke to bring her up a smidge. If I were further down I'd use power but I would make any adjustments in very small increments so as not to oscillate on the GS.
 
AdamZ said:
Depends on how far below the GS I was. If I was not far I'd be more inclined to just use the yoke to bring her up a smidge. If I were further down I'd use power but I would make any adjustments in very small increments so as not to oscillate on the GS.
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:yeahthat:
 
Like all approach and landing questions, it is a question of energy management. If you pitch up, you will get a momentary altitude gain but lose airspeed/energy. Your closest source of energy that does not cost airspeed (assuming that you are trimmed for approach speed) is the throttle.

Bob Gardner
 
Richard said:
You're flying an ILS in the plane you most often fly. Inside the OM you notice you begin to dip below the GS. Do you make no adjustment to power settings as you roll in some up elevator trim or do you increase power settings?
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Am I on speed or fast? If I'm on speed, I add power. If I'm fast, I pitch/retrim for on-speed and see what happens.
 
Heh. My marker beacon receiver started beeping in cruise a couple weeks ago and it took me a second to figure out what the hell it was. :(
 
depends on what i did to get below in the first place
 
nosehair said:
So I have to ask; why do you want to know?

(sounds like the ol' pitch/power/airspeed/altitude debate)
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My thoughts were not exactly the power/pitch debate. I have seen pilots yoyo-ing on the approach while chasing airspeed. The biggest factor I think is not flying the 'numbers' as it pertains to power settings. So they guess how many RPMs to bump it up. Anyway, they are lagging.
 
I never answered the question, but here are my questions back...

How low? Half a dot? One dot? More?

Needle moving? Getting worse or better? (If correction started, needle responding or stuck?)

Airspeed fast, on speed, or slow? (Do we have excess energy to pitch up with, since we should have been trimmed for this descent.)

Single-glideslope panel or two? Cross-check!

Altimeter agree? Moving down or up? Cross-check!

Are we descending or just low? (I'm stuck in editing mode now - this may have been given in the question but I can't re-read it ATM.)

ILS ID'd? ;) (The tricky one... You even flying a localizer there bub, or just some white noise and the glideslope transmitter just failed...)

Are we even flying an ILS approach? ;)

Co-located localizer only approach? What's the MDA on it? Are we above it? What's the MSA circle say about our predicament? (Is it peanut-butter-jelly dance/emergency climb right now time?)

Are we covered in ice? (Good chance we don't really get another shot at this, since going missed may not be a real option? -- Mayday. Haha!)

What's the current power setting? (Re: Ball of ice, above.) Already at WOT and full prop RPM? (Ohhh crap!!!)

Aircraft have a GPS/VOR switch for the number 1 OBS? Or a single OBS and a Nav 1/2 switch?

Any flags? (Uhh, duh...)

Oh and the ultra-duh... Some glideslope intercept points are beyond the OM on a few odd-ball approaches, aren't they? Are we even at the intercept point/altitude expected for this particular approach? (I think there's a few like that anyway...)

There's so many possible factors here...
 
denverpilot said:
I never answered the question, but here are my questions back...

How low? Half a dot? One dot? More?
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Goodness! Don't let me guide your response. In the OP I did say, "...you notice you begin to dip below...". To me that means...a little bit or maybe an increasing trend.... If you have your scan going it should mean within PTS standards.

Needle moving? Getting worse or better? (If correction started, needle responding or stuck?)
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How concerned are you that you should be even a little bit low? How low is too low? What are you willing to tolerate/accomodate/accept? Am I wrong in thinking the GS is a hard deck and should not be transgressed? So whether it is low (needle not moving) or the beginning of a downward trend (needle moving), will you accept either condition?

Airspeed fast, on speed, or slow? (Do we have excess energy to pitch up with, since we should have been trimmed for this descent.)
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Here is a good reason why I left my question purposefully vague. In your mind, in your own words, what will you do to correct? I will say though that a proficient instrument pilot WILL be trimmed at least by the OM, even if turned early on vectors (Crap, I know I shouldn't have just said that...I've been turned inside the OM...anyway, assume on speed if you must.)

Single-glideslope panel or two? Cross-check!
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Excellent cockpit management. So assume dual receivers in agreement with dipping below GS...now how do you correct?

Altimeter agree? Moving down or up? Cross-check!
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Ibid

Are we descending or just low? (I'm stuck in editing mode now - this may have been given in the question but I can't re-read it ATM.)
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Seems like you are repeating your earlier question. But on approach you ARE descending...but at specified rate of descent. Ye shalt avoid a faster rate in the descent.

ILS ID'd? ;) (The tricky one... You even flying a localizer there bub, or just some white noise and the glideslope transmitter just failed...)
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Now you're just making it up. If in doubt or instrument flagged, do not pass go, do not collect $200, go directly to missed approach.

Are we even flying an ILS approach? ;)
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What are you drinking tonight?

Co-located localizer only approach? What's the MDA on it? Are we above it? What's the MSA circle say about our predicament? (Is it peanut-butter-jelly dance/emergency climb right now time?)
Click to expand...

I say you have flown past your duty time.

Are we covered in ice? (Good chance we don't really get another shot at this, since going missed may not be a real option? -- Mayday. Haha!)
Click to expand...
I give up!

What's the current power setting? (Re: Ball of ice, above.) Already at WOT and full prop RPM? (Ohhh crap!!!)

Aircraft have a GPS/VOR switch for the number 1 OBS? Or a single OBS and a Nav 1/2 switch?

Any flags? (Uhh, duh...)

Oh and the ultra-duh... Some glideslope intercept points are beyond the OM on a few odd-ball approaches, aren't they? Are we even at the intercept point/altitude expected for this particular approach? (I think there's a few like that anyway...)

There's so many possible factors here...
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Is Bellvue still in operation? One of their loonies is missing.

EDIT: Okay, just for you...you intercepted the GS at the Maltese Cross on altitude and on speed. Then begins the fun. Now...answer the Q.
 
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I don't think it's kind you got personal, calling me a looney. The scenario's not real enough to be the dynamic environment we know as flight.

My point was, without any situational awareness of how I magically arrived at your mystical point in time, where I'm suddenly flying an approach and I'm slightly low...

Easy lame answer: Low on glideslope, Go up. Can't go up? Level off and let the glideslope come back in. Don't go down further is probably close enough to the desired result. Can't level off, 'cause you're carrying a metric ton of ice, you're going down if you don't want to stall.

In the real world given only the information you gave, I'd probably go missed and figure out what State I'm in, and over which airport. Might even be great to know what I'm flying. ;)

These contrived scenarios aren't real. People ask them assuming a lot of stuff and want to know "What would you do?" They're common on written tests but those tests are taken knowing the assumptions the test giver is operating under. I can't guess yours.

Airspeed is going to be affected by the pitch change, if you're talking fixed-wing. That's a given.

If you were already fast due to the downward deviation, great. You had a little extra energy in the bank. Take it out and spend it. If you're going too slow you're going to have to add power to hold level flight.

Maybe you just plopped me into a helicopter and I need to pull collective and add power? ;)

Maybe I'm in a giant transport category airplane and significant inertia is involved and must be taken into account? (Or as our transport category guy joked, the auto throttles or autopilot just failed?)

Maybe I'm seeing an instrumentation failure?

Maybe I'm flying a twin with one caged and losing airspeed puts me below blue-line? (Better not climb. Descent may be the only option left.)

I can't help it if my imagination can fill the void of information given with a whole lot of scenarios, good and bad, that could be faced in the real world by different pilots of different craft, and are. It's a "choose your own adventure" story.

I get the feeling from the personal attack you have a more specific scenario in your mind's eye, but didn't articulate it. That's no problem, but the answers will vary wildly with the scenarios we can all imagine.

Did we even determine if we're IMC? What can I see out the window? (I assume we're IMC, but assumptions in flying are generally bad news.) ;) ;) ;)

There are even those who'd say, "If I'm a dot low, I'll just fly the whole thing a dot low." Most of us would find that very foolhardy, but he'd survive it since he's still in the protected zone of the ILS. He'd also hit DH sooner and a little further away from the airport, and lose a chance of seeing the airport, perhaps.

Is that answer more to your liking? I'm not trying to tick you off. Sheesh.

Low? Go up. That covers it I guess.
 
Richard said:
You're flying an ILS in the plane you most often fly. Inside the OM you notice you begin to dip below the GS. Do you make no adjustment to power settings as you roll in some up elevator trim or do you increase power settings?
Click to expand...

I can't answer this question as the premise is flawed.
 
Richard said:
You're flying an ILS in the plane you most often fly. Inside the OM you notice you begin to dip below the GS. Do you make no adjustment to power settings as you roll in some up elevator trim or do you increase power settings?
Click to expand...

It depends. For example, if the airspeed good, I'll add power.
 
Here's a related question, let's say you're flying a coupled approach with a glideslope enabled autopilot. How do you set your power? Wait for it to stabilize on the glideslope then set for airspeed?
 
Sac Arrow said:
Here's a related question, let's say you're flying a coupled approach with a glideslope enabled autopilot. How do you set your power? Wait for it to stabilize on the glideslope then set for airspeed?
Click to expand...

As I intercept the GS, I reduce the power to what I expect will give me the airspeed I want, based on previous experience. Then I adjust it as needed, and power is for airspeed and the autopilot manages pitch to stay on GS.
 
Sac Arrow said:
Yes, of course - specifically a DA40.....
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I have George fly the plane, and I play the part of the autothrottle to get it down to my approach speeds. Worked great on Sunday when I flew the ILS 18 into KMSN down to 600'.
 
TMetzinger said:
As I intercept the GS, I reduce the power to what I expect will give me the airspeed I want, based on previous experience. Then I adjust it as needed, and power is for airspeed and the autopilot manages pitch to stay on GS.
Click to expand...

vontresc said:
I have George fly the plane, and I play the part of the autothrottle to get it down to my approach speeds. Worked great on Sunday when I flew the ILS 18 into KMSN down to 600'.
Click to expand...

When do you guys disconnect the autopilot? Minimums? When you have visual?
 
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