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Descend via mach number until intrcptng 280

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Old 03-08-2021, 03:00 PM
  #21  
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Originally Posted by EMAW View Post
OK. So I assumed and early descent because it’s happened to me before that way. Either way the question and answer is the same, whether you were cruising lower at 300 kts or given “descend and mantain” a lower altitude earlier that would allow you to maintain 300 KTS.
No, it is not the same.

If an aircraft departs, climbs to a cruise altitude of FL240, and crosses KOZAR as part of a filed or cleared arrival, the KLYNK3, The first speed restriction applicable on that arrival is found at EEEZI.

If ATC desires a different speed, ATC will need to assign the speed. If the pilot is in doubt of the clearance, he is required to query ATC. This is a regulatory requirement.

A wise pilot will enquire.

"I asked my ATC buddies" does not cut it. What is applicable is the clearance. If cleared for the arrival, any speed restrictions on that arrival will apply, unless an amended clearance is received. An aircraft which never climbed above FL240, and thus is not descending to that altitude, will never be reaching a mach cruise number. If the aircraft is cruising at 300 knots, there is no procedural note for the KLYNK3 arrival which dictates slowing from 300 knots to 280 knots, until EEEZI.

An astute pilot may note that an arrival at 300 knots will potentially place one faster than traffic descending into the arrival, and may query ATC to ask about speed, if a speed has not been assigned. One should NOT assume ATC intent, or guess at the speed. One should not arbitrarily reduce speed, because the procedure does not call for it. If ATC has not assigned a speed reduction prior to that established by the STAR, then it's entirely possible that ATC is using the speed difference for spacing. What "ATC buddies" think does not trump what is printed on the arrival, nor a clearance issued by the controller working that aircraft and that arrival. One must fly the arrival as published, and fly the clearance as given, or as amended.

The KLYNK3 arrival does not provide a speed reduction or speed restriction until EEEZI, except that aircraft descending from an altitude at which a mach number is in use, will maintain 280 as that airspeed is reached in the descent. There is no procedural note requiring or directing arriving aircraft to reduce airspeed speed to 280 knots until arrival at EEEZI.

It should be noted that an aircraft that transitions from mach to an indicated airspeed is not making an airspeed reduction. The procedural requirement is to maintain 280 knots when that speed is reached; an aircraft descending on a mach number is actually increasing airspeed until 280 knots is achieved. Think about it.
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Old 03-08-2021, 03:59 PM
  #22  
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Originally Posted by JohnBurke View Post
No, it is not the same.

If an aircraft departs, climbs to a cruise altitude of FL240, and crosses KOZAR as part of a filed or cleared arrival, the KLYNK3, The first speed restriction applicable on that arrival is found at EEEZI.

If ATC desires a different speed, ATC will need to assign the speed. If the pilot is in doubt of the clearance, he is required to query ATC. This is a regulatory requirement.

A wise pilot will enquire.

"I asked my ATC buddies" does not cut it. What is applicable is the clearance. If cleared for the arrival, any speed restrictions on that arrival will apply, unless an amended clearance is received. An aircraft which never climbed above FL240, and thus is not descending to that altitude, will never be reaching a mach cruise number. If the aircraft is cruising at 300 knots, there is no procedural note for the KLYNK3 arrival which dictates slowing from 300 knots to 280 knots, until EEEZI.

An astute pilot may note that an arrival at 300 knots will potentially place one faster than traffic descending into the arrival, and may query ATC to ask about speed, if a speed has not been assigned. One should NOT assume ATC intent, or guess at the speed. One should not arbitrarily reduce speed, because the procedure does not call for it. If ATC has not assigned a speed reduction prior to that established by the STAR, then it's entirely possible that ATC is using the speed difference for spacing. What "ATC buddies" think does not trump what is printed on the arrival, nor a clearance issued by the controller working that aircraft and that arrival. One must fly the arrival as published, and fly the clearance as given, or as amended.

The KLYNK3 arrival does not provide a speed reduction or speed restriction until EEEZI, except that aircraft descending from an altitude at which a mach number is in use, will maintain 280 as that airspeed is reached in the descent. There is no procedural note requiring or directing arriving aircraft to reduce airspeed speed to 280 knots until arrival at EEEZI.

It should be noted that an aircraft that transitions from mach to an indicated airspeed is not making an airspeed reduction. The procedural requirement is to maintain 280 knots when that speed is reached; an aircraft descending on a mach number is actually increasing airspeed until 280 knots is achieved. Think about it.

exactly. Which is why I said ask.

however, you said once assigned the arrival any speeds on the arrival apply. How does a note that says descend in MACH until intercepting 280 not apply to the whole arrival meaning at KOZAR. Show me something from the FAA, or a legal interpretation and I will adjust my way of thinking. If you have a reference that gives this specific example, post it. I’d be glad to adjust what I do. But until then, I’ll take “I asked my buddy at ATC what they expect” over someone I’ve never met on a forum. I was just giving some different
points of view. Never trying to pass off what I say as gospel and I’ve said multiple times now if in doubt, query.

I have been unable to find this specific example in any example.

This is nothing but a discussion. Curious as to the right answer myself.
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Old 03-08-2021, 10:14 PM
  #23  
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Crossing KOZAR the airplane is established on the STAR. Per FAA Order 7110.65Y:
  1. Aircraft will meet all published speed restrictions when on any route or procedure with published speed restrictions regardless of climb via or descend via clearance.
The same Order references ATC use of Mach number at or above FL240. At FL240, 300 knots is equivalent to M70. What if M70 is your speed at FL240. The transition is for spacing, as such logically it doesn’t make sense that aircraft in descent must slow at transition to 280, but the airplane at FL240 can maintain “300 knots” since that is what was maintained in “cruise”.

‘Consider an airplane at FL360 and M84. This equates to 280 knots indicated, which would require 280 knots to be maintained crossing KOZAR.

Here is a NASA report for the HAWKZ RNAV arrival in KSEA, which includes the same note: NOTE: Turbojet aircraft descend via mach number until intercepting 280K. Maintain 280K until slowed by the STAR:

Title: An A319 flight crew; descending via the HAWKZ RNAV STAR to SEA and maintaining assigned .73M; was criticized by Center for not being at 280 KTS when checking in with the next Controller. The chart; however; specifies flights are to descend via Mach number until 'intercepting' the required 280 KIAS until slowed by ATC.

Narrative: SEA Center controller assigned us to slow to .73 Mach. Got a frequency change to SEA Center 128.3. The 128.3 controller asked us our speed and we told her 310 kts. We had not intercepted 280 kts yet. She told us we were supposed to be at 280 kts. Note on Hawkz3 reads Speed restriction: Turbojet aircraft descend via Mach # until intersepting 280 kts. Maintain 280 until slowed by STAR. Flight continued without incident.

Of course querying ATC is good practice if unsure, but the argument for 300 knots to EEEZI is pretty thin in my view.
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Old 03-09-2021, 12:20 AM
  #24  
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The ASRS excerpt above is irrelevant with respect to the question at hand.

The controller told the crew to be at 280 knots when they were still descending at mach, in compliance with the star, and had not yet reached 280 knots. If the controller wanted something other than the current clearance to fly the STAR, then the controller would need to change the clearance, by issuing a new or amended clearance. The fact that the controller told the crew that they should have been at 280 knots, does not change the fact that the crew was in compliance, and the controller was wrong, until an amended clearance were issued.

A flight shall comply with the speed restrictions applicable to the arrival. A flight which is not descending at mach is NOT expected to transition to 280 knots from mach. The flight cannot transition to 280 knots from mach, because the flight was never there.

One does not prove a negative. Prove that the flight must be at 280 knots, in compliance with a descent restriction, when the flight isn't descending? No need. The restriction does not apply. Prove that the flight must comply with a mach transition instruction when the flight is not at an altitude at which it is operating by mach, and does not perform the transition? No need. It's irrelevant.

If the arrival required 280 knots from KOZAR, the arrival would so state. Prove that it doesn't? Can't prove a negative. The proof is that there is no such requirement. Aircraft descending into the arrival transition from mach. Aircraft not descending into the arrival meet their first speed restriction at EEEZI.

In the case of the airbus crew and their ASRS report, the reporter notes that "the flight continued without incident." Of course it did. The crew did nothing wrong, and was in compliance with the arrival. Again, one doesn't have need to prove a negative. The crew was in compliance.

It's also irrelevant to the question at hand; arrival in cruise at a speed above 280 knots.

Where is it written? On the arrival. The first speed restriction is EEEZI. Descending aircraft fransitioning from mach do so at the transition. Aircraft not transitioning have their first published speed restriction at EEEZI.

You are not expected to comply with procedural notes or restrictions that do not apply, and you are required by regulation to query ATC if you have a question or if the clearance is in doubt. Hardly "thin." It's the law.
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