Question about crossing an intersection at a given altitude

[Insane]

So the following scenario often happens to me and I always resolve to look it up when I get on the ground but never do... Being incurably lazy, I'm now going to turn to those-who-know here and ask what I should do (and no I don't know how to use the search button ).

I am coming into a towered airport under the Bravo shelf of a major airport on an IFR plan, and get a STAR. As I get close, the final center controller tells me to "cross BLABBY intersection at and maintain 7000". So I set up to do that, and need to descend at 900ft/min to make that. Fine. I'd prefer to descend at 500ft/minute but I can manage that. That center controller then five minutes later hands me off to the approach controller while I'm still at let's say 11,000 feet and on target to crossing BLABBY at 7000 as requested. But now the approach controller immediately tells me to "descend and maintain 5000 feet". What I ALWAYS do then is make sure I go ahead and cross BLABBY at 7000 (or lower) and then continue on to 5000 ft at a more leisurely 500 ft/minute. The question that always comes into my mind is, does the new altitude restriction supercede the old one and can I descend to the new altitude at let's say 500 ft per minute? Since I am in a piston I could be excused for wanting to descend at a more comfortable 500ft/minute. I always assume NO and basically obey both instructions from the two different controllers.

So what do you do in this situation?

 

[dell30rb]

Pretty sure your new altitude instructions supersede the old ones.

If the new controller still needs you to cross BLABB(Y)? at 7000, he should say so. Or if he needs you to make an expedited descent on down to 5000.

 

[midlifeflyer]

does the new altitude restriction supercede the old one and can I descend to the new altitude at let's say 500 ft per minute?

If the new cleared altitude does not restate the restriction, it's gone. See AIM 4-4-10.g. and its examples.

In case of doubt, though, you could have always replied, "descending 5,000, still need me to cross BLABBY at or below 7,000?"

 

[MarkZ]

2 answers here.

First, book answer. When ATC issues a new altitude, the controller must restate the crossing restriction. New altitude clearances negate previously issued crossing restrictions. So, TECHNICALLY, once approach issues "descend and maintain 5,000" that clearances voids the "cross BLABY at 7,000" restriction. The controller should issue "cross BLABY at (or above/below) 7,000, descend and maintain 5,000."

Second, my answer. If you already set up your plane to make the crossing, why change it? I've had pilots of the same airline that shall be unnamed "teach" a lesson during my first years checked out. What crap. I'll issue a descent clearance, because I was lazy, saw a good rate of descent, and didn't feel the need to restate the crossing, whatever. Some witty pilot will cut off that good descent rate and descend at a pitiful 500 ft/min. When I'm cranking the aircraft out for traffic and ready to eat the pilot's lunch, the pilot informs me (correctly) that I negated the crossing.

Be nice. Ask the controller if they need you to continue to make the crossing. We do make mistakes. Throw us a bone.


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[dell30rb]

Second, my answer. If you already set up your plane to make the crossing, why change it?

Usually 900 FPM is no problem, but it can get uncomfortable in unpressurized airplanes. I'm not that sensitive to it (unless I have a cold) but I know people who are.

 

[midlifeflyer]

If you already set up your plane to make the crossing, why change it?

Because a 900 FPM descent may (and usually is) uncomfortable for passengers in an unpressurized piston aircraft. If I can end it early, I will.

 

[MarkZ]

Because a 900 FPM descent may (and usually is) uncomfortable for passengers in an unpressurized piston aircraft. If I can end it early, I will.

Groovy, and I get it. I also fly FLIB's VFR and IFR. I hate descending more than 500 ft/min if I don't have to.

Why not throw the controller a bone and ask if they need the restriction?

Sure, I get it, you don't have to ask the controller. That wasn't the point I was making.


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[peerlesscowboy]

Groovy, and I get it. I also fly FLIB's VFR and IFR. I hate descending more than 500 ft/min if I don't have to.

Why not throw the controller a bone and ask if they need the restriction?

Sure, I get it, you don't have to ask the controller. That wasn't the point I was making.


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Yes, I think we should remember that we (pilots and controllers) are on the same team.

 

[midlifeflyer]

Groovy, and I get it. I also fly FLIB's VFR and IFR. I hate descending more than 500 ft/min if I don't have to.

Why not throw the controller a bone and ask if they need the restriction?

Sure, I get it, you don't have to ask the controller. That wasn't the point I was making.


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You'll notice I suggested it in my post as a way to avoid any confusion on the subject. I generally would since I know the restriction was probably due to traffic issues and controllers can be as imperfect as I am.

 

[Insane]

Groovy, and I get it. I also fly FLIB's VFR and IFR. I hate descending more than 500 ft/min if I don't have to.

Why not throw the controller a bone and ask if they need the restriction?

Sure, I get it, you don't have to ask the controller. That wasn't the point I was making.


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Isn't that first instruction by the center controller technically TWO clearances?

First one: Cross BLABBY at 7000 ft
Second one: Descend and maintain 7000 ft

The controller then combined them into a single sentence using AND but they are two instructions are they not?

In which case the approach controller replaced the second one with Descend and Maintain 5000 ft. At least that is what was going through my mind. ??? I agree it would be better to ask for clarification.

In this particular case I heard the center controller give someone else much faster behind me a crossing altitude of 9000 ft at the same intersection so it seemed kind of important to me to go ahead and cross BLABBY at 7000ft (and not, say, 9000 ft once I heard the new clearance).

 

[midlifeflyer]

The controller then combined them into a single sentence using AND but they are two instructions are they not?

Even if you treat them separately, the AIM says the later clearance voids the restriction in the prior one.

I agree it would be better to ask for clarification.

Always, even if it's "just" what you would like to do. Needs to repeat that "and" you are inferring.

 

[MarkZ]

Isn't that first instruction by the center controller technically TWO clearances?

First one: Cross BLABBY at 7000 ft
Second one: Descend and maintain 7000 ft

The controller then combined them into a single sentence using AND but they are two instructions are they not?

In which case the approach controller replaced the second one with Descend and Maintain 5000 ft. At least that is what was going through my mind. ??? I agree it would be better to ask for clarification.

In this particular case I heard the center controller give someone else much faster behind me a crossing altitude of 9000 ft at the same intersection so it seemed kind of important to me to go ahead and cross BLABBY at 7000ft (and not, say, 9000 ft once I heard the new clearance).

If I read your OP correctly, you said the center controller issued "cross BLABY at and maintain 7000." If that is correct, that is one clearance. In laymen terms, the controller cleared you to cross a point in space at a specified altitude and stay there. When the approach controller issued the descent to 5,000 he negated the restriction.


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[Insane]

If I read your OP correctly, you said the center controller issued "cross BLABY at and maintain 7000." If that is correct, that is one clearance. In laymen terms, the controller cleared you to cross a point in space at a specified altitude and stay there. When the approach controller issued the descent to 5,000 he negated the restriction.


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Makes sense. Thanks. Next time I will ask for clarification. This exact scenario has happened to me three or four times at the same location over the last six months, and I've wondered each time. It wasn't a big deal to just continue the same rate of descent to that intersection so that's why I never asked. But now I'm curious what the intent really is and I'll ask next time.

 

[roncachamp]

So what do you do in this situation?

The new clearance wipes out the crossing restriction. If 7,000 at BLABY was still to apply the new clearance should be issued as "cross BLABY at 7,000, descend and maintain 5,000."

 

[roncachamp]

Isn't that first instruction by the center controller technically TWO clearances?

First one: Cross BLABBY at 7000 ft
Second one: Descend and maintain 7000 ft

The controller then combined them into a single sentence using AND but they are two instructions are they not?

It's one clearance with too many words. It should be just "cross BLABY at 7,000". You descend so as to reach 7,000 not later than BLABY and maintain that altitude until further advised.

 

[MarkZ]

It's one clearance with too many words. It should be just "cross BLABY at 7,000". You descend so as to reach 7,000 not later than BLABY and maintain that altitude until further advised.

At the center, the phraseology police made a huge push that controllers must issue the crossing as "cross BLABY at and maintain 7000." The reason being what I stated a few posts ago.

 

[roncachamp]

At the center, the phraseology police made a huge push that controllers must issue the crossing as "cross BLABY at and maintain 7000." The reason being what I stated a few posts ago.

Bad cops. What else would a pilot do after reaching the specified altitude?

 

[MarkZ]

Bad cops. What else would a pilot do after reaching the specified altitude?

That was the exact argument I used when one of those cops tried to hang one of my guys for "blatant disregard for prescribed phraseology." He was so used to saying the clearance the obvious way, and this "cop" was bored. Or had a bug up his butt. Something. But I digress...

It should be obvious, but the book has the phraseology.

 

[roncachamp]

That was the exact argument I used when one of those cops tried to hang one of my guys for "blatant disregard for prescribed phraseology." He was so used to saying the clearance the obvious way, and this "cop" was bored. Or had a bug up his butt. Something. But I digress...

It should be obvious, but the book has the phraseology.

Prescribed by what? The cops? The book says:

PHRASEOLOGY−
CROSS (fix, waypoint) AT (altitude).

 

[MarkZ]

Prescribed by what? The cops? The book says:

PHRASEOLOGY−
CROSS (fix, waypoint) AT (altitude).

Don't kill the messenger. Read further down Chapter 4-5-7 d., and under the examples, it says

EXAMPLE−
“United Four Seventeen, cross Lakeview V−O−R at and maintain six thousand.”
NOTE−
The pilot is authorized to conduct descent “at pilot’s discretion,” but must comply with the clearance provision to cross Lakeview VOR at 6,000 feet.

 

[roncachamp]

Don't kill the messenger. Read further down Chapter 4-5-7 d., and under the examples, it says

The point is not including "and maintain" is not "blatant disregard for prescribed phraseology."

 

[MarkZ]

The point is not including "and maintain" is not "blatant disregard for prescribed phraseology."

Sigh…

I just showed you where the book shows an example of the correct phraseology to use, in the proper context to use it.

Anyways, it happened. Cops went after my guy. My guy made the conscious effort to use "and maintain" and the cops backed off.

Let it go. We did.

 

[coma24]

I wouldn't seek clarification now that you're more familiar with the regs. There is no ambiguity. You should descend at a rate that is optimal for your aircraft, just like any other climb or descent.

 

[midlifeflyer]

Sigh…

I just showed you where the book shows an example of the correct phraseology to use, in the proper context to use it.

Anyways, it happened. Cops went after my guy. My guy made the conscious effort to use "and maintain" and the cops backed off.

Let it go. We did.

I'm sure you're aware by now that doesn't happen.

 

[roncachamp]

Sigh…

I just showed you where the book shows an example of the correct phraseology to use, in the proper context to use it.

Anyways, it happened. Cops went after my guy. My guy made the conscious effort to use "and maintain" and the cops backed off.

Let it go. We did.

You didn't show me anything I wasn't aware of and you're still missing the point. The cops are wrong, the inclusion of "and maintain" in a clearance to cross a fix at a specific altitude is not required by Order 7110.65.

 

[dell30rb]

"cross BLABY at 7,000".

I see you caught that as well. (5 Letters)

 

[Insane]

I see you caught that as well. (5 Letters)

Apologies it was a fake intersection. BLABY doesn't exist, or at least I don't think it does.

But my fake intersection should have been five letters.

I should be flogged!

 

[jesse]

I would just respond with "down to 5,000" and continue at my current rate until I was there. The new instruction from the new controller supersedes the previous one. If the approach controller isn't smart enough to know that, well, they'll learn. I'm not going to waste "air-time" by verifying that which should be. If everyone verified everything nobody would get a word in

I try to keep the "big picture" in my head of what all is going on and pay attention to all transmissions to do that. If I thought there was a mistake being made or some sort of safety issue I'd certainly start clarifying things but this one is pretty basic.

 

[MarkZ]

You didn't show me anything I wasn't aware of and you're still missing the point. The cops are wrong, the inclusion of "and maintain" in a clearance to cross a fix at a specific altitude is not required by Order 7110.65.

h. The annotation EXAMPLE provides a sample of the way the prescribed phraseology associated with the preceding paragraph(s) will be used. If the preceding paragraph(s) does (do) not include specific prescribed phraseology, the EXAMPLE merely denotes suggested words and/or phrases that may be used in communications.
NOTE−
The use of the exact text contained in an example not preceded with specific prescribed phraseology is not mandatory. However, the words and/or phrases are expected, to the extent practical, to approximate those used in the example.

This is what the cops used. Bold italics emphasis are mine.

I got your point when you first jumped on the soap box. I got that the rest of this paragraph makes your case as much as it does the cops. I'm telling you, it's been a soap box argument that went nowhere.

Say it's wrong all you want, but it is what it is.

 

[Insane]

I would just respond with "down to 5,000" and continue at my current rate until I was there. The new instruction from the new controller supersedes the previous one.

Okay, but if you do that and just maintain your current rate, you are not actually letting the second instruction supersede the first one since your current rate will get you crossing BLAB(B))Y at 7000ft. Did you mean you would adjust your downward rate? I was descending 900ft/min. My action was to continue 900ft/min until past that intersection then slow my descent to 500 ft/min until I reached 5000 ft. I could have just immediately slowed my descent to 500 ft/min according to the rules.

 

[jesse]

Okay, but if you do that and just maintain your current rate, you are not actually letting the second instruction supersede the first one since your current rate will get you crossing BLAB(B))Y at 7000ft. Did you mean you would adjust your downward rate? I was descending 900ft/min. My action was to continue 900ft/min until past that intersection then slow my descent to 500 ft/min until I reached 5000 ft. I could have just immediately slowed my descent to 500 ft/min according to the rules.

This just all depends on the scenario -- do I have passengers? What airplane? What are the winds doing? Whats the field elevation? How far out am I? Is there an approach I'll be flying? What's the terrain like? Is an off-field landing survivable? etc. Sometimes a descent rate is going to put me past Vne without a major power reduction and a sudden major dramatic power reduction is often something I avoid depending on the powerplant.

So really, it just depends. There are times to where I'm doing everything I can to stay as high as I can as long as I can and there are other times I want to be lower.

In this case if 900/fpm were a problem for you and you'd rather be at 500 fpm then do that.