Captain Toolbox (WARNING! LONG RANT!)

Tony the reg does not stop you from going below the glide slope. Find me the reg that says you have to land at the aim point! Please!
 
Explain how you'll take the 747 from on glideslope at 200' to touching down less than 500' down the runway using normal rate of descent and normal maneuvers.

Come on - - you said any airplane could do it.
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I already answered this, but I'll do it again. Besides a 30kt tail wind, I just talked to one of my Polar pilot friends. Here is what they are taught.

They must cross the threshold at 47' AGL to avoid hitting any ILS equipment. So postulate a 300'/mile stabilzed descent +- 100' (or approx 1000fpm descent rate at 164 kts)

This equates to a no wind touch down point approximately 892 feet down the runway. Any headwind at all and they can land at 500 ft.

Hope this answers your question.

By the way - what equipment do you fly?
 
Kingairer said:
Just curious how long this runway was. I cant think of one that you actually need the mains to touch down on the numbers. Ill said it again, its all about the briefing.
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KingA, if you're talking about the runway I was on, it was 6,500 ft, with another runway crossing it at the far end. But just to clarify the quickly muddying waters: I wasn't trying to put it down on the numbers. I was trying to put it down as close as possible to the 1000' markers while holding 5 knots extra airspeed.
But! You're right, I should have briefed it. Looking back, I can remember flying with guys who did the same thing, but told me they were going to and why. It was a mistake to assume that such a common flying technique should not be briefed.

As to the 'putting it on the numbers' argument: This is a good one, however far afield from the original post it may have strayed. As much as I want to disagree with TC's argument (his ingratiating tone motivates that) I have to say he may have a point. I am hard pressed to imagine any 'normal rate of descent or normal maneuvers' that would allow a 747 to leave the MM or PAPI and hit the numbers, rendering the manuver technically against the regs. It should be noted, however, that this illegality is dependent on tecqnique; as soon as we have a 74 driver step up and say "Oh, sure you can, here's how..." the argument goes in the gutter.
 
Mr_Creepy said:
Tony the reg does not stop you from going below the glide slope. Find me the reg that says you have to land at the aim point! Please!
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You must learn to focus better if we are to have an intelligent conversation here. Find me a reference to where I said anyone has to land at the aim point.

The argument that I have submitted is that one must remain at or above the glideslope, whether it is electronic (ILS) or visual. I have provided quotes from 14 CFR that support my position, save the interpretation of the MM inbound portion of the ILS, and the "necessary for safe landing" part of the visual.

That's where I posed the scenario of the 747 changing everything at the MM to land on the numbers - - how can he do it?


Mr_Creepy said:
I already answered this, but I'll do it again. Besides a 30kt tail wind, I just talked to one of my Polar pilot friends. Here is what they are taught.
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Is that your answer? 30kt head wind? (I'm assuming your tail wind here was a typo, based on your Post # 55)

OK. Let's talk geometry. A 3 degree descent gradient will have you lose 318 feet (round it to 300 if it makes you feel better) for every one NM travelled along the ground. 3 degrees in no wind is the same as 3 degrees in a tail wind is the same as 3 degrees in a head wind. If the wind is blowing at 100 knots off the nose, 3 degrees is still 3 degrees.

The geometry is independent of winds. To phrase it another way, it doesn't matter what the winds are, a 3 degree descent gradient is still a 3 degree descent gradient.

Comparing a calm wind 3 degree descent with a light headwind 3 degree descent, the former will require less power, result in a slightly higher descent rate, and will require a very slightly higher deck angle than the latter. BOTH will have a STABLE power setting, STABLE deck angle, and STABLE descent rate. Both will require a deviation from that power setting, deck angle, and descent rate to achieve something MORE than a 3 degree descent gradient to land short of the previously stabilized point.



Mr_Creepy said:
They must cross the threshold at 47' AGL to avoid hitting any ILS equipment. So postulate a 300'/mile stabilzed descent +- 100' (or approx 1000fpm descent rate at 164 kts)

This equates to a no wind touch down point approximately 892 feet down the runway. Any headwind at all and they can land at 500 ft.

Hope this answers your question.
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Again - - and I'm glad you explained what you're thinking so we can really address the problem head on - - a stabilized descent at 300 ft per NM in ANY wind conditions will result in the exact same aim point. To follow your logic would mean that landing in a 50 knot headwind would result in landing short of the runway. That's simply not true.



Mr_Creepy said:
By the way - what equipment do you fly?
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I don't, I just stayed at a Holiday Inn Express once.




:)




I fly the 727 currently. I have flown and instructed on the MD-11/MD-10. I flew RC-135's in the Air Force. We use the same concepts for the DC-10 and the A300. I used the same concepts in the T-37.



OK. So let me ask once more, and you're going to have to some up with a better answer than "30 kt head wind."

You're in your mighty 747 (care to guess how much inertia you're dealing with here?) and you're stable on a 3 degree glidepath. You have established a power setting, a deck angle, and a descent rate (VVI) that holds the glidepath perfectly. Now you're at the MM, 200' above the ground.

Exactly what will you do with the throttles, and the yoke, to make the airplane land, using normal descent rates and normal maneuvers, to change your descent gradient and land on the numbers?

Your copilot is the type that will say "Unstable, Go-Around" if he sees any parameter out of tolerance, so be careful. And please be specific.



:)



.
 
First of all - yes - I meant head wind. Thanks for pointing that out.

My 747 pilot friend says that the angle of descent for them is more like 6 degrees at some airports, such as Abu Dabi (sp?) in Saudi Arabia.

Let me see if I can quote him:

"A short runway for us is 8500' and we are required to land in the touchdown zone (defined as first half of runway). If we can make the numbers without hitting anything we will (i.e. displaced threshold) and we always use the top bars of a double vasi or papi. When we're dropping in to a high threat zone in the desert, we want to come down fast to keep the exposure to (some acronym for hand launched missiles - I didn't write it down) to a minimum."

Before I answer to your question, the biggest aircraft I have landed is a 737-700, hardly a "heavy", so my experience is limited.

I did land it on the numbers at FLL one night, unintentionally! It was gusty winds and I flared just in time to plant the main gear right on the "9L" - the captain was nervously teasing me about leaving scrape marks on the belly from the ILS towers all he way in on the taxi, but the walkaround showed no contact (and thankfully no damage!) It was probably my worst landing ever, but I did cross the MM at DH.

You are right about angles and winds - I thought of that as I pushed "Post Quick Reply" - and of course I meant relative descent angles, not absolute.

But your last comment got me wondering. I don't think there is time from MM to touchdown to even say "Unstable, Go-around" especially if the flying pilot is also saying "Runway in sight, Landing."

I've never realy considered the possible safety hazard of initiating a go-around below DH. Have to think about that one.

This has been a good conversation, thank you.
 
Mr_Creepy said:
First of all - yes - I meant head wind. Thanks for pointing that out.

My 747 pilot friend says that the angle of descent for them is more like 6 degrees at some airports, such as Abu Dabi (sp?) in Saudi Arabia.

............
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Abu Dhabi, United Arab Emirates. ;)

(And no I didn't Google it. I wad there while in the Navy)
 
For the record, I agree 100% with Tony on this one. I have nothing to add, he's explained it quite well.
 
Mr_Creepy said:
My 747 pilot friend says that the angle of descent for them is more like 6 degrees at some airports, such as Abu Dabi (sp?) in Saudi Arabia.

Let me see if I can quote him:

"A short runway for us is 8500' and we are required to land in the touchdown zone (defined as first half of runway). If we can make the numbers without hitting anything we will (i.e. displaced threshold) and we always use the top bars of a double vasi or papi.When we're dropping in to a high threat zone in the desert, we want to come down fast to keep the exposure to (some acronym for hand launched missiles - I didn't write it down) to a minimum."
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Clearly he's describing a scenario far removed from flying a stabilized 3 degree glidepath. There is little doubt that he would not use this 6 degree angle of descent on a CAT II ILS. Even so, a contradiction jumps out at me even in this description. On the one hand, he speaks of hitting the numbers, but on the other hand, he "always use the top bars of a double vasi or papi." [your emphasis] Perhaps I've been misinformed, but I thought the whole purpose of the 3-bar VASI was to provide a visual indication to pilots of jumbos such as the 747 to prevent landing short. I'm pretty certain it does not display a 6 degree descent gradient.


Mr_Creepy said:
But your last comment got me wondering. I don't think there is time from MM to touchdown to even say "Unstable, Go-around" especially if the flying pilot is also saying "Runway in sight, Landing."
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Good! I'm glad you're seeing one of the difficulties of the scenario: there is very little time. There's not a lot of time to push the nose over, pull the throttles back, wait for the VVI to settle, adjust the power, ignore the VGSI, adjust the pitch angle, etc., to fly this new glidepath from the middle marker to "the numbers." There's very little margin for error.

On the other hand, there's plenty of time for a professional pilot. At 200' on a 3 degree glidepath, you're still 2/3 mile from touchdown. At 120 kts groundspeed, that still gives you 20 seconds. When things are going wrong, 20 seconds can seem like an eternity. :)

Or, it can seem like merely a flash.

I guess it depends on which temporal distortion phenomenon is most powerful at that second. Or, the 20 seconds. :) ;)


Mr_Creepy said:
I've never realy considered the possible safety hazard of initiating a go-around below DH. Have to think about that one.
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I think this is a fresh can of worms... hang on... easing the top off here.... pfffffffffft... yepp, it was fresh, but now it's open... :)


While you're thinking about that...

Try considering a go-around in the flare. Try considering a go-around after the mains are alreay on the ground and the throttles are at idle. Try considering a go-around after you've already deployed the speedbrakes.

There are times when executing a go-around from those points are the most safe course of action. In fact, if you're doing one of these landings where you must get the airplane on the ground and begine braking by 1,000' in order to stop within the remaining runway, what are you going to do if you don't get it perfect, if you wind up landing 1,100' feet down the runway? By the definition supplied in the problem, you're now in a situation where it is impossible to stop before exiting the end of the runway. What are your options?

Different airplanes have different limits, but one I use and one I've heard frequently, is if I haven't initiated use of the thrust reversers, I'm still capable of executing a go-around.

So, flying the glideslope, roundout, flare, float... float..., I see that I'm not going to touch down within the TDZ because I screwed it up - - go-around.

Different scenario, I touch down in the TDZ, but something else threatens the safe outcome of the landing - - call it the proverbial bus-load of nuns entering the runway. If I haven't activated the thrust reversers, I can still go-around.

Runway condition reported as fair, and I can stop safely with anything fair or better. I land normally and discover it's actually poor to nil - - go-around.





If we're looking for a reg that says, "Thou shalt never dip below glidepath," we're not going to find it. The regs that we do have, though, combined with an understanding of the physics involved with changing a stablized approach to accomplish this maneuver scream at me that I should stay on the glidepath.

Now, B767Driver, by citing engineering data that describes something different, has piqued my interest that there might be a manufacturer-approved method of doing something different. Always willing to learn, I'm simply trying now to determine how the switch is made in this very short, very low, very critical period of time.

And while I'm thinking of it... surely the data assumes a higher rate of descent. Are there any associated lower weight limits described for this maneuver?



.
 
"Runway condition reported as fair, and I can stop safely with anything fair or better. I land normally and discover it's actually poor to nil - - go-around."

So, you're gonna land your 727. Deploy speedbrakes. Not deploy reverse while you are discovering that the braking action is really poor, and not fair, cob the power to it and go around? Doesn't seem like a very likely scenario. Espcially when the book says on contaminated runways that use of max reverse as soon as possible is important.

I don't disagree that the book doesn't say you can't go around after landing and deploying speedbrakes. I just thought your scenario was a stretch and really can't see a scenario where it makes sense to go around after landing and deploying speedbrakes. That's one we've never done in the sim but maybe I can ask next time.

JT. There has been a big emphsis on stabilized approach criteria lately. At my company, they even changed it to 1000AGL from 500AGL after deciding guys were coming in hot too often. If you're 6 knots fast at 400 AGL, 11 knots fast at 900 AGL, or exceed 1000fpm descent below 1000AGL, you're supposed to go around no matter what. That's what the book says, these days.

I think it really takes the judgement and experience factor out of the go around decision. The real question is....is that a good thing?
 
We're at 1000' for stabilized as well.

As for go arounds, with autospeed brakes, I have done more than one go around in the sim with them deployed right at touchdown. The "tower" go around call is just as you touch down, but with normal reaction time, the boards are out before you can get the power up to knock them down.
 
Don we also had the 1000' stabilized rule at Mesa, Eagle and Midway.

I don't think you're unstabilized if you drop the nose a hair after MM and go about 1 dot low, just to give yourself more room to land, especially with any kind of headwind.

This discussion has gotten very technical but the main point is, any pilot with judgement is going to use all the runway available!
 
Mr Creepy--

I would say that "any pilot with judgement" is going to maintain the glideslope until flare, not carry extra energy to smooth out the landing, and land on runways that have adequate length. You are advocating a VERY bad habit, that *might* work in little airplanes, but not a good idea if you ever get into any sort of big aircraft.

As Tony said, how is it going to sound at the hearing? You are setting yourself up for one by ducking under the glideslope like that!
 
We've shown that you can, once you reach the MM.

I would not be shy about that at a hearing. I'd be more worried if I didn't go below and slid off the end, wouldn't you?
 
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