5-5-7 passing or diverging

[Sassyquatch]

The rule states
" TERMINAL. In accordance with the following criteria, all other approved separation may be discontinued and passing or diverging separation applied when:
a.)...aircraft are on same or crossing courses/assigned radar vectors and one aircraft has crossed the projected course of the other, and the angular difference between their courses/assigned radar vectors is at least 15 degrees.

NOTE-
Two aircraft, both assigned courses and/or radar vectors with an angular difference of at least 15 degrees, is considered a correct application of this paragraph.

b) The tracks are monitored to ensure that the primary targets, beacon control slashes, FUSION target symbols, or full digital terminal system primary and/or beacon target symbols will not touch."

The key issue is "assigned radar vectors". Management is saying aircraft must be established on 15° or more before you apply passing and diverging, but it does not read that way. It reads if you assign a vector that ensures 15° and apply subparagraph b, then you can use passing and diverging prior to the aircraft turning 15° or more.

This is a specific application where I work due to a departure course and arrival course to a satellite airport diverging by 8°. Specifically if an aircraft goes around at the main airport and you have someone on final to the satellite airport.

Management refuses to submit an interpretation request, I've asked at least twice already. Their reasoning is it takes too long to get an answer back. We've been arguing this rule since February. They have email correspondence with a QA/QC person who was once a supervisor here. I've been told it was an "unofficially official interpretation to the rule". Their exact words. The email said the same thing I was told, stating "[QA/QC] opinion is that both aircraft must be established on the headings diverging by 15° or more".

 

[DADDYSbabyBIRD]

Just from my experience with the rule at 3 different facilities from 2 different regions... Must be established on the 15 degrees or more.
"Are on"
Not "are assigned"

I get how you could attempt to argue how it reads that they just need to be assigned the heading, but if you look at how the sentence is structured and think why they wrote it that way it becomes clear that it's just saying they can either be on some type of predetermined course (SID, Victor airway, missed approach track, ect) or a radar vector assigned by you or another controller.

 

[ATOH]

We've had this debate as well.

Since it states assigned headings not observed headings I agree with you personally. Just being through projected flight path and assigned a difference of 15 degrees is clean in my book.

 

[Dolan]

You can have 2 aircraft on top of each other 1k feet apart who diverge by one degree. As long as their paths have crossed you can assign a new heading that diverges by 15 degrees or more and assign one the same altitude as the other in the same transmission.

 

[Termine]

I don't have any deeper knowledge than my own reading of the text, but the way I read the text of the paragraph itself, they need to be established.

"Aircraft are on ... assigned radar vectors."

But the note seems to contradict that reading, because it says "Two aircraft, both assigned ... radar vectors with an angular difference of at least 15 degrees, is considered a correct application of this paragraph."

I don't know if the meat of that note is the "and/or" which means you're allowed to assign one a course/route and the other a radar vector and still be legal, or if the meat is the "assigned" which means they don't have to be actually established yet in order to be legal. Or maybe both meanings are intended.

 

[Acquired Taste]

The basic idea of this paragraph is you better ensure the actual flight paths between the 2 aircraft is at least 15 degrees, or else you don't have divergence. It doesn't matter how you get there. You can assign a radar vector. You can clear them direct to a fix. Either way, you better make sure have 15 degrees before you lose another form of separation of it's a deal.

For example, let's say the winds aloft are 360 @ 25 kts. You have one a/c cleared to a fix and the course to heading is a true 270. In the cockpit, he might actually be showing a 280 heading. If you have another a/c 1000 ft directly on top of them and tell them to fly heading 285 and descend 1000 ft, you do no have separation because his true course would actually be closer to 275, only 5 degrees of separation from a/c #1.

On the other hand, if you assign a/c number 1 heading 270 and assign a/c number 2 heading 285, then once they are actually established on that heading, you can lose other forms of separation and apply divergence. I would argue Dolan is wrong. You can issue a turn that differs from the other a/c by 15 degrees and an altitude in the same transmission, but ONLY if you specify and separate the turn first, and THEN (once established on the heading), descend/climb and maintain XXX.

 

[bravounite33]

The key issue is "assigned radar vectors". Management is saying aircraft must be established on 15° or more before you apply passing and diverging, but it does not read that way. It reads if you assign a vector that ensures 15° and apply subparagraph b, then you can use passing and diverging prior to the aircraft turning 15° or more.

You're reading what you want to read that benefits you. You're completely ignoring the part where it says "aircraft ARE ON same or crossing courses/assigned radar vectors." This is very rare for me to say but your Management is actually correct. Once you get 15° or more diverged, you can lose separation.

 

[Sassyquatch]

The basic idea of this paragraph is you better ensure the actual flight paths between the 2 aircraft is at least 15 degrees, or else you don't have divergence. It doesn't matter how you get there. You can assign a radar vector. You can clear them direct to a fix. Either way, you better make sure have 15 degrees before you lose another form of separation of it's a deal.

For example, let's say the winds aloft are 360 @ 25 kts. You have one a/c cleared to a fix and the course to heading is a true 270. In the cockpit, he might actually be showing a 280 heading. If you have another a/c 1000 ft directly on top of them and tell them to fly heading 285 and descend 1000 ft, you do no have separation because his true course would actually be closer to 275, only 5 degrees of separation from a/c #1.

On the other hand, if you assign a/c number 1 heading 270 and assign a/c number 2 heading 285, then once they are actually established on that heading, you can lose other forms of separation and apply divergence. I would argue Dolan is wrong. You can issue a turn that differs from the other a/c by 15 degrees and an altitude in the same transmission, but ONLY if you specify and separate the turn first, and THEN (once established on the heading), descend/climb and maintain XXX.

I believe this is an incorrect usage of the rule. #1 aircraft dct FIXES, it is a 270° regardless of what the cockpit says. The 2nd aircraft can't be directly on top of the 1st to use degree divergence. "The tracks are monitored to ensure that the primary targets... will not overlap." Doesn't matter how many degrees you use, targets must not overlap. So they are separated by 1 mile now, #1 is on a course and #2 will be assigned 285° regardless of the wind in order to apply this rule.

"Once they are actually established on that heading" is the issue I have specifically with mgmt, because the word "established" isn't anywhere in this rule. It isn't stated here & there wouldnt be an additional note saying "two aircraft both assigned radar vectors...is considered correct application".

If they meant established, it should be included somewhere. And the note makes it even more ambiguous

You're reading what you want to read that benefits you. You're completely ignoring the part where it says "aircraft ARE ON same or crossing courses/assigned radar vectors." This is very rare for me to say but your Management is actually correct. Once you get 15° or more diverged, you can lose separation.

The first part of the rule that I left out is "Aircraft are on opposite/reciprocal courses and you have observed that they have passed each other; or aircraft are on same or crossing courses/assigned radar...".

The part of the rule you quote is merely a reference to the definitions of courses in 1-2-2. It has no bearing on the second part I'm interpreting.... the difference between established on, and assigned.

 

[rhombus]

Everyone is assuming the word ‘on’ applies to both scenarios but you could very easily break down the sentence as:

Aircraft are on same or crossing courses
Aircraft are assigned radar vectors

It’s still grammatically correct if you omit ‘on’ for the radar vectors. You can definitely argue that assigning the radar vectors (assuming they meet the 15 degree rule) is enough and you don’t have to wait for them to make the full turn before you can discontinue other approved separation.

 

[Acquired Taste]

I believe this is an incorrect usage of the rule. #1 aircraft dct FIXES, it is a 270° regardless of what the cockpit says. The 2nd aircraft can't be directly on top of the 1st to use degree divergence. "The tracks are monitored to ensure that the primary targets... will not overlap." Doesn't matter how many degrees you use, targets must not overlap. So they are separated by 1 mile now, #1 is on a course and #2 will be assigned 285° regardless of the wind in order to apply this rule.

"Once they are actually established on that heading" is the issue I have specifically with mgmt, because the word "established" isn't anywhere in this rule. It isn't stated here & there wouldnt be an additional note saying "two aircraft both assigned radar vectors...is considered correct application".

If they meant established, it should be included somewhere. And the note makes it even more ambiguous

Okay, yes, slightly bad wording on my part. The targets can not touch. But as soon as you have a pixel of separation between AND 15 degrees, you are clean. Regardless, if #1 is on a course of 270° and #2 assigned is assigned a heading of 285°, separation is NOT ensured. Hypothetically, the winds could aloft could be 360 @ 100 kts and #2 could be 1 mile due north of #1, assigned a 285° heading, and be actually track a 260° course, converging with the 270° course #1 is on. You have to be entirely sure the planes are going to track 15° difference on your scope. If you clear them both direct to fixes that are 15° or more, it is ensured. If you assign them both a vector, it is ensured as they both will encounter the same winds aloft, although I would probably use 20° to be safe. However, if you mix them, you could potentially end up with tracks that differ by less than 15° and would therefore not be clean.

 

[Dolan]

On the other hand, if you assign a/c number 1 heading 270 and assign a/c number 2 heading 285, then once they are actually established on that heading, you can lose other forms of separation and apply divergence. I would argue Dolan is wrong. You can issue a turn that differs from the other a/c by 15 degrees and an altitude in the same transmission, but ONLY if you specify and separate the turn first, and THEN (once established on the heading), descend/climb and maintain XXX.

There's no argument - the paragraph is crystal clear. You don't have to have 15 degrees before losing other forms of separation. All you need is 15 degrees of divergence on the assigned heading and any level of divergence on the current heading (providing flight paths do not cross). You can have planes 800 feet apart vertically and 10 degrees divergence in one radar sweep and be completely clean.

 

[Acquired Taste]

There's no argument - the paragraph is crystal clear. You don't have to have 15 degrees before losing other forms of separation. All you need is 15 degrees of divergence on the assigned heading and any level of divergence on the current heading (providing flight paths do not cross). You can have planes 800 feet apart vertically and 10 degrees divergence in one radar sweep and be completely clean.

It is anything but crystal clear. You are making a huge leap saying that as soon as you issue the heading, it's clean. I disagree.

 

[ATOH]

It is anything but crystal clear. You are making a huge leap saying that as soon as you issue the heading, it's clean. I disagree.

Is the heading not assigned once its been issued and read back?

 

[Acquired Taste]

Is the heading not assigned once its been issued and read back?

I think you guys are bending the spirit of the rule here. Let's reverse the scenarios a little bit here. Let's say you have two B737s, both at 250 kts. #1 is heading 090 at 11,000. #2 is heading 180 at 12,000. #2 passes directly over top of #1. When #2 is 1 mile south of #1, the controller tells #2 to turn left heading 090, descend and maintain 10,000 knowing that by the time #2 rolls out of the turn, they will have at least 3 miles of sep with #1. By the counter argument's application of the rules, this is a deal because they would no longer be considered passing and diverging because they were 1 mile apart and both assigned the same heading. That would be pretty dumb, right?

The intent of the rule is that you can use assigned courses and/or assigned vectors to accomplish 15 degrees of divergence, but you need to actually ensure you have 15 degrees between the tracks, 1 a/c passing through the flight path of the other, and then you can lose your other forms of separation.

 

[Dolan]

I think you guys are bending the spirit of the rule here. Let's reverse the scenarios a little bit here. Let's say you have two B737s, both at 250 kts. #1 is heading 090 at 11,000. #2 is heading 180 at 12,000. #2 passes directly over top of #1. When #2 is 1 mile south of #1, the controller tells #2 to turn left heading 090, descend and maintain 10,000 knowing that by the time #2 rolls out of the turn, they will have at least 3 miles of sep with #1. By the counter argument's application of the rules, this is a deal because they would no longer be considered passing and diverging because they were 1 mile apart and both assigned the same heading. That would be pretty dumb, right?

It would be a deal if you had less than 1k feet or 3 miles in that scenario, since you wouldn't be able to argue divergence but if you keep one of those you'd be clean.

Same scenario but aircraft #2 is an F16 that turns on a dime and drops 500 feet in 1 radar tick - you'd agree that it would be a deal then right?

 

[Acquired Taste]

It would be a deal if you had less than 1k feet or 3 miles in that scenario, since you wouldn't be able to argue divergence but if you keep one of those you'd be clean.

Same scenario but aircraft #2 is an F16 that turns on a dime and drops 500 feet in 1 radar tick - you'd agree that it would be a deal then right?

That would indeed be a deal if they have less than 15 degrees of divergence between the tracks before they had another form of separation.

Let's make the scenario a little more extreme. Let's say they're still both 737s 250 kts separated by 1,000 feet. #1 heading 090, #2 heading 270 pointed directly at each other. The second they are tail to tail, the controller tells #2 to fly heading 090 and descend through #1's altitude. By your logic, that is a deal because as soon as you assign the heading, you can no longer use passing diverging even though there is a 0% chance they will lose mileage/altitude prior to losing 15 degrees divergence between the tracks.

Just as my hypothetical doesn't instantly give a controller a deal the instant the heading is assigned, your hypothetical doesn't instantly ensure you are legally separated.

 

[Sassyquatch]

That would indeed be a deal if they have less than 15 degrees of divergence between the tracks before they had another form of separation.

Let's make the scenario a little more extreme. Let's say they're still both 737s 250 kts separated by 1,000 feet. #1 heading 090, #2 heading 270 pointed directly at each other. The second they are tail to tail, the controller tells #2 to fly heading 090 and descend through #1's altitude. By your logic, that is a deal because as soon as you assign the heading, you can no longer use passing diverging even though there is a 0% chance they will lose mileage/altitude prior to losing 15 degrees divergence between the tracks.

Just as my hypothetical doesn't instantly give a controller a deal the instant the heading is assigned, your hypothetical doesn't instantly ensure you are legally separated.

You can assume separation will exist by the time #2 is turned. Assuming separation because of aircraft characteristics is part of our job. There are other factors involved that you're ignoring, like turn rate. A B737 isn't going to go from 270 to 090 in a millisecond and he'll be like 5 miles away from where he first started the turn once established on the 090°.

Now if you used something like a IFR C150 then obviously in these scenarios you will most likely have a loss of separation when putting them on the same exact heading. You've given yourself a watch situation. And why did we start giving examples of assigning a/c the same exact heading? Degree divergence does not involve putting aircraft on the same heading.

The "assigned radar vector"& "course" is something you're trying to define as the exact heading an aircraft is flying. They make it ambiguous on purpose. No where in the book does it state "15° or more from the exact heading of two aircraft when winds are accounted for". Dct FIXES is a 270°. I'll give my second aircraft 285° for divergence regardless of wind. And that is a correct application to this rule. Doesn't matter what either aircraft is tracking or if the wind gives my 2nd 280°. They will NEVER hit and I'm applying the rule as it states. Now, if the winds are just ridiculous and aircraft #2 appears to be more in line with 270° and overtaking #1, you use your best judgement to avoid an unsafe situation.

 

[rhombus]

The intent of the rule is that you can use assigned courses and/or assigned vectors to accomplish 15 degrees of divergence, but you need to actually ensure you have 15 degrees between the tracks, 1 a/c passing through the flight path of the other, and then you can lose your other forms of separation.

That seems like over controlling. Let’s say you’re using Runway 27. Two 737s. First 737 is given runway heading. You get 6000 and airborne, second 737 is given a 255 heading and cleared for takeoff. Are you saying you’re going to wait until that second 737 is established on a 255 heading before switching them to departure?

It doesn’t matter if there’s only 2 miles of separation between those 737s when the second one rotates. You assigned 15 degrees of divergence between them and can switch the second 737 to departure as soon as you want.

 

[AB19]

That seems like over controlling. Let’s say you’re using Runway 27. Two 737s. First 737 is given runway heading. You get 6000 and airborne, second 737 is given a 255 heading and cleared for takeoff. Are you saying you’re going to wait until that second 737 is established on a 255 heading before switching them to departure?

It doesn’t matter if there’s only 2 miles of separation between those 737s when the second one rotates. You assigned 15 degrees of divergence between them and can switch the second 737 to departure as soon as you want.

Yeah this is what I was thinking cause without it how are places like ORD launching guys that fast lol

 

[DADDYSbabyBIRD]

Yeah this is what I was thinking cause without it how are places like ORD launching guys that fast lol

Because that's a whole other set of rules.
Read 5-8-3
And tower is applying other forms of separation ex: visual