Captain Toolbox (WARNING! LONG RANT!)

DE727UPS said:
"But, I don't fly it as much either...probably only once for every 5 757 flights."

I didn't know they cross trained you guys at DL. I guess it's just the international guys that only need to know the 767. Domestic needs to know both?

Question for B767 and TonyC.

Does it say in your book not to follow a two bar, 3 degree, VASI if that's all you have? It says that in ours in big bold letters but it's in the pilot training guide, which, strangely enough, isn't read too often unless you're going through transition/upgrade. I don't remember it from the AOM or FOM and certainly haven't run across any Capts that not to follow it.

This would apply to both the 757 and 767.


DE,

Yea, we fly the 757, 767-200, 767-300, and the 767-300ER all interchangeably in the domestic category. Actually, lot of differences to all of those airplanes.

Our FCTM says the use of 2bar VASI system is not recommended, but gives landing geometry data for its use. Main gear crossing height at the threshold is 28'.

Mandatory missed approach is full scale glideslope deflection.
 
Tony, if you don't see all this as hair-splitting, I dread to think how long your posts will be when you acutally do get down to splitting hairs. But, just for fun, and to underline the hair-splittedness of the whole thing, I'll try a Tony-style-three-screen-length-quote-and-rebuke post, and pray god the message isn't lost in all the html code. Here goes:

TonyC said:
<sigh>

There may be confusion on your part because I'm responding to you about what I said regarding B767Driver's posts.

There's no confusion on my part whatsoever. I understood perfectly well that by saying
TonyC said:
OK, so you got me. I'm not confused at all - - I was just trying to be polite. For your sake, I should have said, "You have contradicted yourself. First you say, in describing your version of a 'duckunder', that you are busting a minimum altitude by descending below the DH without adequate visual reference, and then in the next post you claim you have not busted a minimum altitude because you have satisfied the requirements of descending below DH."
you were telling me that you were being polite to B767 by feigning confusion, rather than implying that I was saying something I didn't say, which I clearly didn't. That would be confusing. We're totally on the same page there.
TonyC said:
You can call it whatever you want - - it's violating a minimum altitude. One may not descend below those minimmum altitudes, legally, without adequate visual reference.
No argument there. It is indeed violating a minimum altitude, and you may not legally do it. We are trying to draw the distinction between 'violating a minimum altitude', shown to be synonymous the aforementioned coloquialism 'ducking under', and going below GS or PAPI past the MM in visual conditions, which is indeed legal. Our only trouble now is to show that it can be safely done with normal manuvers and descent rates, and this argument will be stitched up like a pillow case.
TonyC said:
The 3 degree descent gradient does not disappear, evaporate, or vaporize at the middle marker. Even if the ILS glideslope is NOTAMED unreliable below 200' AGL, even if there is NO VGSI, there is still a 3 degree descent gradient that should be maintained. Going below that normal descent gradient is called "ducking under."
Here I disagree with you, ref. last paragraph. But really, the point is moot because "ducking under" has no formal definition. You say tomato, I zader matermorts. The essential argument is whether or not it is legal to descend below glideslope or VGSI after the MM. I, and others on this board, contend that is is not only legal, but safe, given normal manuvers and descent rates.
TonyC said:
I'm sorry, I don't know which post was the "next post" and I don't know what you mean by "doesn't qualify."
This is the post I am referring to:
TonyC said:
...I should have said, "You have contradicted yourself. First you say, in describing your version of a 'duckunder', that you are busting a minimum altitude by descending below the DH without adequate visual reference, and then in the next post you claim you have not busted a minimum altitude because you have satisfied the requirements of descending below DH."
And by "dosen't qualify" I am, of course, stating that B767 has not satisfied the requirements for 'ducking under' by his definition and mine. By yours, it may qualify as a duckunder, but as I've already stated this is merely semantics, and at any rate a long way from resolving the question of legality.
TonyC said:
I do know that he said "being on G/S, below DH, without the necessary visual cues in sight...is a "duck under". Like I just told you, I responded to him that the maneuver he just described constitutes busting a minimum altitude. He answered that such was not busting a minimum altitude, as he had satisfied that at the DH. Of course, that defies logic, since he began by saying that it was descending below the DH without adequate visual reference. Not having "necessary visual cues in sight" does not satisfy the requirement to continue the ILS below DH. In those two remarks, he contradicted himself.
It seemes clear to me that although he did not explicitly spell it out the second part of B767's post assumes visual refrence, otherwise, yes, it would be contradictory.
TonyC said:
Normal maneuvers, normal descent rates.... ahh, yes... we're back to the question I asked. How does one land on the numbers using normal maneuvers and normal desent rates from the on-glideslope, at Decision Height point? Only Mr_Creepy has ventured a response so far. His method is to lower the nose at DH, make no other adjustments, and flare at the normal point. (I haven't pinned him down yet on whether it's a faster flare or a firmer touchdown.)

Perhaps you'd care to expound on the normal manuevers, normal descent rates to the numbers maneuver.
I'll give a stab at it, using my original situation as an example: In the ERJ, 3 degree slope is typically maintined at target speed with flaps 45, 2 degrees nose up pitch, and an 64% N1. If you were foolish enough to disregard flaring, maintaining this configuration and attitute all the way down will *firmly* plant the mains on the 1000' markers. Not good, obviously. Per our CFM, transition to Vref (Actuallt, within 5 knots of Vref! Per CFM!!) should occur when crossing the threshold. This, of course, obviates the need for a small reduction in power as well as a pitch change, which will change our touchdown point. At appx. 10 ft., round-out is initiated, with simultaneous smooth reduction to idle thrust, followd by a flare of appx 2-3 degrees of pitch change(not pitch angle). The airspeed transition, roundout, and flare all conspire to add about 500'-700' to the aim point (1000' markers).
Landing at or before the 1000' markers is therefore academic. Given a displaced threshold of adequate length (which I had-- appx 500' worth) the rate of descent is increased slightly by a small change of pitch and thrust, maintaining Vtgt. This puts you, of course, below both GS and VGSI. At the lower thrust setting, the lapse of time between transition to Vref, roundout, and flare is of course somewhat accelerated, but not to an extent that any pilot of reasonable skill would be unable to contend with. Normal manuvers, normal descent rates, shorter landing, and perfectly legal. You can put a 172 on the numbers easily, an ERJ somewhat more difficulty, a 72 or 73 with even greater difficulty, until you get to a size, speed, and weight that it is almost impossible with normal manuvers and descent rates. I emphasize almost because it, again, is a question of technique. I'm not a 777 or 747 driver, so I'm at a loss to give you techniqe for those types. But, the argument that it is impossible simply because we don't know how is akin to the argument that bumblebees can't fly just because we can't show mathematically how they do it. As soon as you do, the arument goes out the window. If your argument is that it is always illegal, you're argument is already in the shubbery.
TonyC said:
I don't recall taking issue with your phraseology. You might be confused because you asked about my response to B767Driver, and may have mistook my analysis of his posts as an analysis of yours.
Again, no confusion whatsoever. The original argument began along the lines of "Going below GS" vs. "Riding the GS to the ground". I was simply clarifying my original statement, in hopes that it wouldn't get mixed up in all the ducking under and busting altitudes.
TonyC said:
There are some aspects of this business that can be described with very precise terminology, and when we begin using that terminology loosely, it can lead to confusion and misunderstandings. I hope you'll understand this is an endeavor to effectively communicate, and not an exercise in splitting hairs. It becomes much harder when we don't have a nice big whiteboard to draw on. :)
(Still waiting for the "style and delivery" critique. :) )
Good god Tony! If you and I were in a room with a whiteboard and time to kill it would be a nightmare of coffee spills, CFM's, FAR/AIM's, screaming and laughter.

What fun!

I'm reticent to critique your style and delivery; it will almost certainly lead to an argument. But I'll try anyway. Please take it as constructive criticism and not an ego attack. It all stems from your original response to my post...
<insert wavy flashback lines on the T.V. ...>
TonyC said:
Are you sure? :) OK, here goes...


:)
Already, were starting off with a little sarcasm. I was asking for advice and professionalism, not a slap in the face. I'm already frowning.
TonyC said:
If you can't fly the glideslope and safely land in the remaining runway, you don't need to be landing.
Now we have presumptuousness and aspersions cast on my abilities.
TonyC said:
There were two egos in the cockpit.
I had adresed that in my original post. Rubbing salt in the would not only weakens your argument, at comes across as needlessly abrasive, and almost seems done to satisfy your own sense of self-gratification at rebuking my post.
TonyC said:
Calling the tower is NOT the way to initiate a Go-Around.
This one has nothing to do with style and delivery, but I put it in anyway because I wanted to comment on it since we're already on a trip down memory lane. I should let you know that this was an interview question when I was hired, and calling the tower was an appropriate response to an unresponsive captain descending below DH without visual refrence. I will agree, however that in my situation it would not be the appropriate way to initiate the go-around as Captain Toolbox was completely responsive, however, it is not as outside the ream of reason as you seem to make it.
TonyC said:
Take your lessons learned and apply them the next time, and every time, you step into the office.
This, after all the rest, seemed to me the pinnacle of condescention. Who are you to teach me lessons? My experience level is greater than that of a lot of people, but if I had advice for them I certainly wouldn't give it to them with so much high-handedness. Why should you? Ego? If you were referring to the lessons I had already stated having learned, then you're again hailing the cab's taillights- seemingly for your own satisfaction. I value your opinion and respect your experience, but you can keep the patronization. You're a good guy, and sharp, but I hope you can understand how some of the comments you make may rub people the wrong way.
The seeming obstinance and selectiveness shown in many of your responses suggest that it's not really so much about precision, as it is about obscuring or diminishing debated points that you presented so imperiously as undisputable fact, for the purpose of saving face. Had you not attcked the issue so superciliously in the first place, we could all concentrate on the crux of the argument rather than on all the he-said-she-said quote-fest.



The sheer mass of this post I have intended to be part of the critique you asked for. If you skipped to the end of all that mess and just read this, you got the point!
 
DE727UPS said:
Question for B767 and TonyC.

Does it say in your book not to follow a two bar, 3 degree, VASI if that's all you have?

Oh, great. Make me drag the book out. :)


From the FedEx B-727 Flight Manual (I could dig out the MD-11 and the DC-10, but I'm not up to that challenge, yet. :))

Excerpts from Normal Procedures:

LANDING

DESCRIPTION

A smooth touchdown can occasionally be made from a poor approach; however, good landings are made consistently from proper stabilized approaches.


Hard or bounced landings are generally made from steep approaches at higher than normal rates of descent with excessive and/or late flare.


PROCEDURE

CAUTION


Do not "duck under" an established glidepath near the runway threshold to achieve an early touchdown.


Approaching the runway threshold, transition so as to cross the threshold at Bug or Vref + Gust, whichever is higher. ... The aircraft is already very close to the landing attitude, but requires a small additional increase in pitch (2° - 3°) to arrest the rate of descent prior to touchdown. Once the "flare" has begun (approximately 20 feet) smoothly reduce the thrust levers to idle just prior to touchdown. Touchdown should occur at Vref-3. Performance calculations assume the touchdown occurs at this value.

If the aircraft should bounce... When a high, hard bounce occurs, initiate a go-around.

Excerpts from Adverse Weather Operations:

APPROACH AND LANDING

Fly a normal 3° glideslope with an aimpoint of 1000 feet and touchdown of 1500 feet from approach end of the usable runway. Control approach speeds closely ...

Control glideslope path to accomplish touchdown on the runway at 1000 feet from the approach end of the runway. If an unsatisfactory approach is likely to cause touchdown far down the runway, go around and make a second approach.

Touchdown & Landing Roll on Slippery Runways

Fly the aircraft firmly onto the runway at the aiming point, even if speed is excessive.







The guidance for me is pretty clear. I guarantee the guys on the other end of the long green table will have a copy of what I've just shown you.


:)
 
TonyC said:
APPROACH AND LANDING

Fly a normal 3° glideslope with an aimpoint of 1000 feet and touchdown of 1500 feet from approach end of the usable runway. Control approach speeds closely ...

Control glideslope path to accomplish touchdown on the runway at 1000 feet from the approach end of the runway. If an unsatisfactory approach is likely to cause touchdown far down the runway, go around and make a second approach.

Touchdown & Landing Roll on Slippery Runways

Fly the aircraft firmly onto the runway at the aiming point, even if speed is excessive.







The guidance for me is pretty clear. I guarantee the guys on the other end of the long green table will have a copy of what I've just shown you.


:)


This stuff must come from an FAA guy riding a desk. This verbage is in every book...and totally unrealistic.

They tell you to maintain glideslope and plan to touchdown around 1500'...however if the runway is contaminated adjust flight path to touchdown at 1000'. Oh yea, by the way...don't "duck under" the glideslope.

It's totally useless guidance...and this to me...is contradictory.

Anyway...be careful out there guys. Lot's of unrealistic assumptions in all kinds of performance charts.
 
"The guidance for me is pretty clear"

Yeah. That all makes sense. But are you saying it's okay to follow a two bar VASI? UPS says it's not. DL doesn't recommend it. Remember, we are talking about 757/767 here. Maybe it's not addressed in the 727 book.

As far as the men at the other end of the green table. Ours is brown....hehe.
 
B767Driver said:
This stuff must come from an FAA guy riding a desk. This verbage is in every book...and totally unrealistic.

They tell you to maintain glideslope and plan to touchdown around 1500'...however if the runway is contaminated adjust flight path to touchdown at 1000'. Oh yea, by the way...don't "duck under" the glideslope.

It's totally useless guidance...and this to me...is contradictory.

Anyway...be careful out there guys. Lot's of unrealistic assumptions in all kinds of performance charts.

Absolutely. Moreover, it's FedEx company material, not FAR. A different 727 book from a different company may say something different. And, at any rate, it's a long way from "against company regs" to "violating a FAR", which was what the original argument was all about.
 
I'm going to take this a little out of order, and I promise I won't go line by line. :)

CapnJim said:
Good god Tony! If you and I were in a room with a whiteboard and time to kill it would be a nightmare of coffee spills, CFM's, FAR/AIM's, screaming and laughter.

What fun!

I'm reticent to critique your style and delivery; it will almost certainly lead to an argument. But I'll try anyway. Please take it as constructive criticism and not an ego attack. It all stems from your original response to my post...
Hey, name the place, and I'll bring the Dry Erase markers! :)

Honestly, I think that had we been drawing this out, we wouldn't be wrapped around the axle in what this is called and what that is called. I'll try another approach in a minute.


I appreciate you taking the time to give me honest feedback. I see where you're coming from. I didn't intend to come across the way you described, and I'll try to improve the delivery in the future. The first remark was not intended to be sarcastic or a slap in the face, but just plain funny.

I didn't intend to be condescending or abrasive, or to cast aspersions on your abilitites. I didn't presume to be teaching you, either - - I was only offering my opinions, my thoughts. The lessons you learned were certainly not what I had to say, but what the experience itself provided you. Given your perspective on the post, yes, I can see how it could have rubbed you the wrong way.

I'll be more careful to better express my humility in the future. I'll try to remember to use third-person pronouns (one) instead of second-person pronouns (you) so it won't sound like I'm finger pointing. I've also thought about changing my Avatar to friendlier guy - - sometimes I think people confuse his face for my demeanor. It could be no further from the truth. I promise, as soon as we get a contract, he's gone. Until then, I want my brethren to have a constant reminder of the guy we're up against. He's not a nice guy.

I am.

Please accept my humble apology for coming across that way.


CapnJim said:
No argument there. It is indeed violating a minimum altitude, and you may not legally do it. We are trying to draw the distinction between 'violating a minimum altitude', shown to be synonymous the aforementioned coloquialism 'ducking under', and going below GS or PAPI past the MM in visual conditions, which is indeed legal.
I think this may be the heart of our difficulties - which maneuver we happen to be talking about at a particular moment.

Let's try maneuver "A" and maneuver "B" for a few minutes.

Maneuver "A": Descending on glidepath below DH without adequate visual reference.

Maneuver "B": Descending below glidepath close to the runway in order to land earlier on the runway (obviously with adequate visual reference)


Now, don't worry about the names yet. We agree that Maneuver "A" is not legal, correct?

The discussion we're having is about Maneuver "B", correct?


CapnJim said:
Here I disagree with you, ref. last paragraph. But really, the point is moot because "ducking under" has no formal definition. You say tomato, I zader matermorts. The essential argument is whether or not it is legal to descend below glideslope or VGSI after the MM. I, and others on this board, contend that is is not only legal, but safe, given normal manuvers and descent rates.
We agree on the subject of the discussion, and disagree as to the conclusion. ;)


CapnJim said:
This is the post I am referring to:
OK. I think Steve is on to something here. Let me bring back the quote from B767Driver where I think we might have taken different paths:

B767Driver said:
FWIW, I don't like to call this a "duck under" maneuver. To me the term "duck under" implies that I'm at a minimum altitude and I do not have sufficient visual references insight...and I'm busting an altitude to try to see something. For example...being on G/S, below DH, without the necessary visual cues in sight...is a "duck under". In my example...I have the necessary visual cues in sight...I'm adjusting my flight patch visually to achieve a certain touchdown objective. If this adjustment entails a one dot glideslope deviation...I feel certain...knowing the feet of glideslope deviation and my wheel base height...that I'm safe as far as obstructions are concerned.
Using the Maneuvers I described above, I believe we can summarize this paragraph as Maneuver "A", then Maneuver "B". He says that Maneuver "A" is a duck under. He says that Maneuver "B" is not, and Maneuver "B" is perfectly acceptable.

Agreed so far?




OK. This is where I took the first part of his paragraph, the part about Maneuver "A", quoted it, and argued that Maneuver "A" is not "ducking under", but rather busting a minimum altitude.

(We all agree that it's busting a minimum altitdude - - that's not the issue.)


I think he may have mistakenly thought I quoted the portion of the same paragraph that describes Maneuver "B". That's the only way I can explain his response that he satisfied the adequate visual reference at the DH requirement. I just didn't imagine that possibility at the time, because I quoted only that portion of his paragraph that described descending below the DH without adequate visual reference.


How'm I doing? :)


If he was arguing that Maneuver "B" was legal because one has adequate visual reference, while I was arguing that Maneuver "A" was not because one does not have adequate visual reference, then many of the posts that followed make more sense.



Now, as you composed your post, I was composing another, and you can read that above. From our Flight Manual, we read a Caution -- one of those things one must observe (see how I just used the third-person pronoun? :)) to prevent bending metal.

CAUTION

Do not "duck under" an established glide-
path near the runway threshold to
achieve an early touchdown.


I think this describes the Maneuver "B" from above, and it assigns the name that I have associated with it from the start.

Your description of landing the ERJ is very similar to the 727 procedure, or the MD-11 procedure, and I would venture to say, any other large turbine. Does your flight manual describe a method to achive a landing prior to the 1000' point?

Intentionally departing from a stabilized 3° glidepath will involve the same physics in every case - - only the magnitudes will be different. To change the glidepath, the nose must be lowered. To maintain the same airspeed, the throttles must be retarded. The steeper descent angle will necessarily require a higher rate of descent. To achive a touchdown, flare must be initiated earlier, or at a faster rate, unless a harder touchdown is acceptable. An extra 300-400 fpm might not be a big deal in an ERJ. It's a mandatory Go-Around at FedEx (1,000 fpm max), in any airplane, and it might overstress the landing gear for some airplanes at some gross weights. The throttles being at a lower power setting means consideration must be given to throttle reduction during the flare. Should it be sooner, due to the higher descent rate, or should it be later, due to the lower baseline power setting, or should it be the same? Should the throttles be advanced momentarily to help "cushion" the sink rate? What does "the book" say?


Whatever you want to call it, I'm not convinced it's prudent.




It's lunch time now :)


.
 
B767Driver said:
This stuff must come from an FAA guy riding a desk.
Actually, I believe this is from the Boeing manual. FedEx is very paranoid about straying very far from the manufacturer's materials.




Anybody have a Boeing manual handy?


:)
 
DE727UPS said:
But are you saying it's okay to follow a two bar VASI? UPS says it's not. DL doesn't recommend it. Remember, we are talking about 757/767 here. Maybe it's not addressed in the 727 book.

As far as the men at the other end of the green table. Ours is brown....hehe.
I know of no reference to the two-bar VASI in our book, and have used it on many occassions. Perhaps it's unique to the 757/767.


I honestly don't know what color the proverbial table is, and I hope to never learn. :)



.
 
CapnJim said:
Absolutely. Moreover, it's FedEx company material, not FAR. A different 727 book from a different company may say something different. And, at any rate, it's a long way from "against company regs" to "violating a FAR", which was what the original argument was all about.
I didn't present it as a FAR, or as having the same weight or bearing as a FAR. (Of course, it does for me and my airplane, but that's another story.) I presented it in response to DE727UPS's question, "What does your book say?"

The original argument was that you don't need to be landing on a runway where you can't fly the glideslope and safely stop in the remaining runway. The legal part entered the discussion later on. :)


LEGAL

SAFE

SMART


2 out of 3 IS bad. :)



.
 
Man, Tony, I really appreciate you taking the time to respond, very cool of you. I get it!

As to the whole debate, how about this:

Going under GS? Legal, but not recommended.
 
TonyC said:
Actually, I believe this is from the Boeing manual. FedEx is very paranoid about straying very far from the manufacturer's materials.




Anybody have a Boeing manual handy?


:)


This stuff must come from a Boeing guy riding a desk. :)

I searched the 84100.10 FAA Inspectors manual regarding this topic and did not uncover any useful information.


TonyC,

It looks like your manual has some mention of landing at 1000'...looks like it was posted out of context...but probably is in the contaminated runway section of your manual. Anyway...next time you are in for training...ask them how you are supposed to transition from the glideslope to touchdown at 1000'.

I'd be interested to see what guidance they give you.

I would guess the answer the FAA/Boeing/Company wants to hear is fly the glideslope to the 1000' point and don't flare. Let it touchdown at 800' per minute.


I'd agree this is what the book data wants us all to do...but unrealistic from my point of view.
 
TonyC said:
The original argument was that you don't need to be landing on a runway where you can't fly the glideslope and safely stop in the remaining runway. The legal part entered the discussion later on. :)


LEGAL

SAFE

SMART


2 out of 3 IS bad. :)



.


I'd say that's wise advice.

My intention was to add that performance data can skew one's perception that landing beyond 1000' presents adequate stopping distance on a contaminated runway. If one touches down beyond 1000' from the threshold it would be wise to add a couple of thousand feet to the contaminated runway landing distance requirements.
 
seagull said:
Hmm, find me a tricycle gear aircraft where the gear is NOT behind the "point of rotation" (also known as the CG, incidentally)!
You'd think so wouldn't you? I never experienced an aircraft that was so glaringly apparent in that category as the 737.

And if I flared at 20' ??? BANG!
 
CapnJim said:
Absolutely. Moreover, it's FedEx company material, not FAR. A different 727 book from a different company may say something different. And, at any rate, it's a long way from "against company regs" to "violating a FAR", which was what the original argument was all about.
In part 121 company regs become FARs! (14 CRFs that is now)
 
TonyC said:
Intentionally departing from a stabilized 3° glidepath will involve the same physics in every case - - only the magnitudes will be different. To change the glidepath, the nose must be lowered. To maintain the same airspeed, the throttles must be retarded. The steeper descent angle will necessarily require a higher rate of descent.
Preface my comments by saying I'm just a flib driver. :)
What are the physics involved that dictate a higher descent (vertical) speed based on a steeper approach path? What if the maneuver were initiated by a reduction in power, with a change in pitch (nose up, not nose down) to end up with a (slightly) steeper approach path, maintaining initial descent rate? Is that even a possibility in transport catagory aircraft???

I'm visualizing a slightly steeper descent (make up numbers - 3.25 degree vs 3 degree???), same vertical speed, same air speed. Probably missing something here, but not sure what it is?




2.gif
 
SteveC said:
Preface my comments by saying I'm just a flib driver. :)
What are the physics involved that dictate a higher descent (vertical) speed based on a steeper approach path? What if the maneuver were initiated by a reduction in power, with a change in pitch (nose up, not nose down) to end up with a (slightly) steeper approach path, maintaining initial descent rate? Is that even a possibility in transport catagory aircraft???

I'm visualizing a slightly steeper descent (make up numbers - 3.25 degree vs 3 degree???), same vertical speed, same air speed. Probably missing something here, but not sure what it is?




2.gif


SteveC,

Here's some info that might answer your question. Basically, if you steepen the descent gradient, but keep the same airspeed, you must increase your rate of descent.

On a typical approach, the descent gradient is 300'/nm...or 3:1. This would put you at 150' agl at .5 nm from the runway. Let's say due to an obstruction in the approach path, you want to stay 200' until .5 nm from the runway. Here's some physics that show what you would need to do. Lets say our groundspeed is 120 kts.

Descent Gradient = Alt to lose (feet)/distance to travel (miles)

So DG = 200/.5 = 400'/nm


Vertical Speed = Descent Gradient ('/nm) * Groundspeed (nm/min)

So VSI = 400 * 2 = 800 '/min


You can also figure out the pitch required for this:

Pitch Change = Descent Gradient/100 = 400/100 = 4 degrees.


So to delay your descent to the runway until at 200' and .5 nm, you need to steepen your approach to the runway to a 4:1 Descent Gradient which would require a Vertical Speed of 800ft/min and a pitch change of 4 degrees from level flight...or about 1 degree more than from a 3:1 glidepath.



These formulas work good for all phases of flight...and even for climbs...just substitue descent gradient for climb gradient and it will give you the required rate of climb for a specific climb gradient.

For descents from Cruise...you can estimate your top of descent by multiplying the altitude to lose by 3. This will estimate where you should begin a descent for a 3:1 profile. Then to find the vertical speed required to stay on that profile...multiply the DG * your Groundspeed for rate of descent in ft/min. At 420 kts you would be traveling 7 miles per minute. So 300 * 7 = 2100 ft per minute to maintain the 3:1 profile. If you needed to lose 20,000' you would begin your descent 60 nm out.
 
Initiate a flare at 30 feet in an MD-88/90, you're going to float, underspeed and still be waiting for those engines to spool up as your tailcone slices into the lumino-reflective centerline paint! :)

"Master Caution"

"TAILCONE UNSAFE"

:)
 
O.K., then going back to the premise of the original question (descent below GS inside MM) would require either:

1. Higher descent rate (airspeed remains constant, steeper approach path), or
2. Lower approach airspeed (descent rate remains constant, steeper approach path).

Sound reasonable?

Third proposed technique:

1. Reduce power,
2. increase pitch slightly to maintain descent rate,
3. accept lower airspeed, resulting in steeper approach path.

Now we are out of parameters by being too slow???

How am I doing?

(Thanks for walking me through this. Takes me a while to catch up with you guys some times.) :)
 
Mr_Creepy said:
In part 121 company regs become FARs! (14 CRFs that is now)
While the FedEx 727 CFM constitutes legal guidance for a FedEx 727 pilot, it certainly would not apply to any other operator, or any other airplane operated by FedEx. I was looking for something from the 14CFR that would apply to everyone. ;)


:)


.
 
Back
Top