HK AIR TRAFFIC CONTROL BLOG
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New Queries with embedded answers
Question:
On departure from RWY 25L, OCEAN 2B, on initial call to departure prior to PRAWN we were given the clearance: “Climb unrestricted to 9000”.
What is the intended meaning of “unrestricted"?[
Ref is to FMC Database Coding. There are no altitude limits in the OCEAN 2B SID, other than TROUT at or above FL140.
You are correct, the OCEAN 2B SID only has TROUT FL 140 as a requirement, but FMC Database coding is the “restricted” that ATC are cancelling. For your reference, Hong Kong’s FMC coding is published in AIC03-10. I do not speak for others but the manager of HK Arrivals and Departures is presently tidying this issue up and his intention is to have all the FMC Database requirements unambiguously published on the SID charts. [As are the STAR charts which were consolidated, simplified and updated on 22 August 2013].
Along the same line…
On arrival when given an altitude crossing restriction ("cross SONNY at FL260") by a controller, then switched to a second controller and issued a lower cleared level ("descend to FL200") prior to reaching the previous fix(SONNY), is the crossing restriction cancelled, or does it still apply? The FL260 requirement still applies because it was not specifically cancelled by ATC. It would be the case where the new controller using “unrestricted” would be clearly canceling the crossing restriction("descend unrestricted to FL200"), but without the use of “unrestricted” is the crossing restriction (SONNY at FL260) still a requirement? Yes, as it is a published restriction (HK AIP ENR 1.10.5) it always applies unless specifically cancelled by ATC.
Hong Kong AIC40-12 is the reference. Part 4 dictates that the requirements at CYBER, SONNY and MAPLE always apply unless specifically cancelled by ATC. HK AIP ENR 1.10.5 notes 3, 4 & 5 is the authority.
From personal observation: ATC usually does not cancel published restrictions unless there is a pressing need and enough lead-in time for the derestriction to become effective. Aircrew often sound surprised when they query a restriction and ATC immediately replies, “Cancel the XXXXX level/speed restriction.”. When not cancelling restrictions, ATC is neither showing indifference or bloody-mindedness but, it is usually, because ATC has weighed up the workload benefit. Their reasoning is that, if there is not enough lead-in time for the derestriction to come into effect and if cancelling incurs added workload for little discernable result, then it is effectively a futile exercise. [This is why it is so important that authorities design TTRs, SIDs, STARs and IAPs that fit seamlessly. Otherwise, operational personnel (both ATC & aircrew) are constantly having to challenge each other because of the designed discontinuities or ambiguities].
On departure from RWY 25L, OCEAN 2B, on initial call to departure prior to PRAWN we were given the clearance: “Climb unrestricted to 9000”.
What is the intended meaning of “unrestricted"?[
Ref is to FMC Database Coding. There are no altitude limits in the OCEAN 2B SID, other than TROUT at or above FL140.
You are correct, the OCEAN 2B SID only has TROUT FL 140 as a requirement, but FMC Database coding is the “restricted” that ATC are cancelling. For your reference, Hong Kong’s FMC coding is published in AIC03-10. I do not speak for others but the manager of HK Arrivals and Departures is presently tidying this issue up and his intention is to have all the FMC Database requirements unambiguously published on the SID charts. [As are the STAR charts which were consolidated, simplified and updated on 22 August 2013].
Along the same line…
On arrival when given an altitude crossing restriction ("cross SONNY at FL260") by a controller, then switched to a second controller and issued a lower cleared level ("descend to FL200") prior to reaching the previous fix(SONNY), is the crossing restriction cancelled, or does it still apply? The FL260 requirement still applies because it was not specifically cancelled by ATC. It would be the case where the new controller using “unrestricted” would be clearly canceling the crossing restriction("descend unrestricted to FL200"), but without the use of “unrestricted” is the crossing restriction (SONNY at FL260) still a requirement? Yes, as it is a published restriction (HK AIP ENR 1.10.5) it always applies unless specifically cancelled by ATC.
Hong Kong AIC40-12 is the reference. Part 4 dictates that the requirements at CYBER, SONNY and MAPLE always apply unless specifically cancelled by ATC. HK AIP ENR 1.10.5 notes 3, 4 & 5 is the authority.
From personal observation: ATC usually does not cancel published restrictions unless there is a pressing need and enough lead-in time for the derestriction to become effective. Aircrew often sound surprised when they query a restriction and ATC immediately replies, “Cancel the XXXXX level/speed restriction.”. When not cancelling restrictions, ATC is neither showing indifference or bloody-mindedness but, it is usually, because ATC has weighed up the workload benefit. Their reasoning is that, if there is not enough lead-in time for the derestriction to come into effect and if cancelling incurs added workload for little discernable result, then it is effectively a futile exercise. [This is why it is so important that authorities design TTRs, SIDs, STARs and IAPs that fit seamlessly. Otherwise, operational personnel (both ATC & aircrew) are constantly having to challenge each other because of the designed discontinuities or ambiguities].
Last edited by psychohk; 1st Mar 2014 at 14:35.
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Additional new posts on HKATCA Website
Several new questions on arrival procedures, altitude restrictions and holding requirements.
HKATCA Official Blog
HKATCA Official Blog
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Feedback
We certainly appreciate the feedback.
We too (ATC) have to make adaptation to a changing environment with rapid movement growth, route structures that need prioritisation and re-vamping and technology integration. What worked yesterday doesn't necessarily work today. Clearly the better we understand each others lot, both parties profit.
Please don't harbour any questions. "there are no stupid questions"
We'll de-identify all questions via email. If you want them answered privately, simply state that and we'll oblige.
The HKATCA will be promoting ATC fam flights as much as possible to our members, so don't hold back with sharing your concerns should one of us join you on a flight.
We too (ATC) have to make adaptation to a changing environment with rapid movement growth, route structures that need prioritisation and re-vamping and technology integration. What worked yesterday doesn't necessarily work today. Clearly the better we understand each others lot, both parties profit.
Please don't harbour any questions. "there are no stupid questions"
We'll de-identify all questions via email. If you want them answered privately, simply state that and we'll oblige.
The HKATCA will be promoting ATC fam flights as much as possible to our members, so don't hold back with sharing your concerns should one of us join you on a flight.
Thanks for the insight regarding HK airspace.
One particular occurrence I have noticed with increasing prevalence is the shortened base turn that follows speed reductions. It happens so regularly APP/ director recognises it and advises the track miles to run. Speed reductions and increased descent rates in jet aircraft don't work! Would it be possible to maintain aircraft speed and add another mile or two??
Every time this happens we are constantly been told to reduce further due to closure rates on preceding aircraft.
One particular occurrence I have noticed with increasing prevalence is the shortened base turn that follows speed reductions. It happens so regularly APP/ director recognises it and advises the track miles to run. Speed reductions and increased descent rates in jet aircraft don't work! Would it be possible to maintain aircraft speed and add another mile or two??
Every time this happens we are constantly been told to reduce further due to closure rates on preceding aircraft.
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So many in ATC appear not to appreciate the inter relationship between speed and descent initiation. Recently told that the F260 constraint would apply at Sonny. Descent delayed due to traffic crossing below. Had passed planned top of descent so started to slow down. ATC come back with "CXXXX are you slowing down", "Affirm (otherwise will be unable to make constraint)". ATC reply with a very curt "maintain speed". I understand that we need to maintain common speeds for separation, but a thinking man in the above situation can see that a slow down pre descent followed by high speed in descent will sort out the requirement to make the constraint and maintain separation.
On a similar vein, do ATC realise how much easier it is for us to cope with speed requirements in the descent if those speeds are given prior to the descent point? Any speed changes in the descent are inefficient, and use more fuel.
On a similar vein, do ATC realise how much easier it is for us to cope with speed requirements in the descent if those speeds are given prior to the descent point? Any speed changes in the descent are inefficient, and use more fuel.
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Thank you for the informative posts. theory behind for us helps 
.
I assume being ex-caa, and the quoted example of "G-AB", "to" is not for all. reference CAA CAP413 affected 2013. http://www.caa.co.uk/docs/33/CAP4132...0117928206.pdf
Chapter 3-1.2.3
Break Break,
Decelerate and Expedite
Realistically, an analogy would be driving down hill, one cannot decelerate and steepen the descent, descent require transfers from potential energy into kinetic energy, as newton states the energy is not loss. Decelerate 210kts expedite descent just cannot be done at the same time.
.
why climb "TO" FL? why descend "TO" FL? ("to" added)
why climb "" ft? why descend "" ft? ("to" omitted)
Both of the above are a product of lack of standardisation. 'TO' is ICAO standard. The examples below are taken from ICAO Telephony Manual. It is becoming common for ATC and aircrew to subtract 'TO' or to add the word 'altitude' to clearances and readbacks. This is not standard ICAO. Some might think it's a good idea, but it's not standard. Sounds a bit anal, but it really is worth sticking to the book, otherwise people go off on their own interpretation and you'll end up with limitless possibilities.
G-AB DESCEND TO FL 60
FASTAIR 345 CONTINUE CLIMB TO FL 330..........CLIMBING TO FL 330 FASTAIR 345
This is an issue with readbacks as well. Generally ATC try to say minimum R/T. Then aircrew journalise it. Not a good idea.
why climb "" ft? why descend "" ft? ("to" omitted)
Both of the above are a product of lack of standardisation. 'TO' is ICAO standard. The examples below are taken from ICAO Telephony Manual. It is becoming common for ATC and aircrew to subtract 'TO' or to add the word 'altitude' to clearances and readbacks. This is not standard ICAO. Some might think it's a good idea, but it's not standard. Sounds a bit anal, but it really is worth sticking to the book, otherwise people go off on their own interpretation and you'll end up with limitless possibilities.
G-AB DESCEND TO FL 60
FASTAIR 345 CONTINUE CLIMB TO FL 330..........CLIMBING TO FL 330 FASTAIR 345
This is an issue with readbacks as well. Generally ATC try to say minimum R/T. Then aircrew journalise it. Not a good idea.
Chapter 3-1.2.3
- "However, care must be taken to ensure that misunderstandings are not generated as a consequence of the phraseology employed during these phases of flight. For example, levels may be reported as altitude, height or flight levels according to the phase of flight and the altimeter setting. Therefore, when passing level messages, the following conventions apply:
- a) The word 'to' is to be omitted from messages relating to FLIGHT LEVELS.
- b) All messages relating to an aircraft’s climb or descent to a HEIGHT or ALTITUDE employ the word 'to' followed immediately by the word HEIGHT or ALTITUDE. Furthermore, the initial message in any such RTF exchange will also include the appropriate QFE or QNH."
Break Break,
Decelerate and Expedite
Realistically, an analogy would be driving down hill, one cannot decelerate and steepen the descent, descent require transfers from potential energy into kinetic energy, as newton states the energy is not loss. Decelerate 210kts expedite descent just cannot be done at the same time.
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KABOY
I'm hearing you.
They are being educated about the incongruity of track shortening and reducing speed in the same breath. It takes time however, and even experienced controllers will argue some interesting rationale for why they find it necessary to do it regularly.
Yes there are times it is necessary to squeeze somebody into a tight gap while avoiding pointing directly at another aircraft but in our normal ops that shouldn't happen too often.
I think it stems from a one-dimensional view that is portrayed by linking the targets in the arrival sequence using a function we have called Range and Bearing Line (RBL). The tendency is then to "chase the tail" of the aircraft ahead looking only at the distance rather than the overall trajectory and energy of the following aircraft i.e think in terms of time to the same point.
We have had a couple of informal get-togethers with both KA and CX pilots which has allowed both sides to discuss the issue and get a better understanding of managing the aircraft's energy more efficiently.
BTC-GC
Well, we pretty much follow ICAO as far as possible. I've often thought UK CAA seem to trip over themselves finding ambiguity in almost anything. Granted, its probably due to bitter experience but at what point do the "belts and braces" stop?
It makes for some pretty wordy R/T when you here somebody say ".... turn right heading xxx degrees, descend to altitude x thousand feet, QNH xxx hectopascals, reduce speed to xxx knots"
In a) above, please explain what ambiguity there can be in "... climb TO Fight Level 330" ?
In b), I believe the inclusion of the word "altitude" is not because of the ambiguity that "TO" might bring, but to highlight the level is referenced to QNH/QFE rather than 1013.
I actually happen to think that is a reasonable inclusion in a busy international environment, given we even have NA CX crews calling HK Approach "... maintaining one three thousand".
I'm hearing you.
They are being educated about the incongruity of track shortening and reducing speed in the same breath. It takes time however, and even experienced controllers will argue some interesting rationale for why they find it necessary to do it regularly.
Yes there are times it is necessary to squeeze somebody into a tight gap while avoiding pointing directly at another aircraft but in our normal ops that shouldn't happen too often.
I think it stems from a one-dimensional view that is portrayed by linking the targets in the arrival sequence using a function we have called Range and Bearing Line (RBL). The tendency is then to "chase the tail" of the aircraft ahead looking only at the distance rather than the overall trajectory and energy of the following aircraft i.e think in terms of time to the same point.
We have had a couple of informal get-togethers with both KA and CX pilots which has allowed both sides to discuss the issue and get a better understanding of managing the aircraft's energy more efficiently.
BTC-GC
I assume being ex-caa, and the quoted example of "G-AB", "to" is not for all. reference CAA CAP413 affected 2013. http://www.caa.co.uk/docs/33/CAP4132...0117928206.pdf
Chapter 3-1.2.3
•"However, care must be taken to ensure that misunderstandings are not generated as a consequence of the phraseology employed during these phases of flight. For example, levels may be reported as altitude, height or flight levels according to the phase of flight and the altimeter setting. Therefore, when passing level messages, the following conventions apply:
◦a) The word 'to' is to be omitted from messages relating to FLIGHT LEVELS.
◦b) All messages relating to an aircraft’s climb or descent to a HEIGHT or ALTITUDE employ the word 'to' followed immediately by the word HEIGHT or ALTITUDE. Furthermore, the initial message in any such RTF exchange will also include the appropriate QFE or QNH."
Chapter 3-1.2.3
•"However, care must be taken to ensure that misunderstandings are not generated as a consequence of the phraseology employed during these phases of flight. For example, levels may be reported as altitude, height or flight levels according to the phase of flight and the altimeter setting. Therefore, when passing level messages, the following conventions apply:
◦a) The word 'to' is to be omitted from messages relating to FLIGHT LEVELS.
◦b) All messages relating to an aircraft’s climb or descent to a HEIGHT or ALTITUDE employ the word 'to' followed immediately by the word HEIGHT or ALTITUDE. Furthermore, the initial message in any such RTF exchange will also include the appropriate QFE or QNH."
It makes for some pretty wordy R/T when you here somebody say ".... turn right heading xxx degrees, descend to altitude x thousand feet, QNH xxx hectopascals, reduce speed to xxx knots"
In a) above, please explain what ambiguity there can be in "... climb TO Fight Level 330" ?
In b), I believe the inclusion of the word "altitude" is not because of the ambiguity that "TO" might bring, but to highlight the level is referenced to QNH/QFE rather than 1013.
I actually happen to think that is a reasonable inclusion in a busy international environment, given we even have NA CX crews calling HK Approach "... maintaining one three thousand".
Last edited by bekolblockage; 4th Mar 2014 at 03:10.
One particular occurrence I have noticed with increasing prevalence is the shortened base turn that follows speed reductions. It happens so regularly APP/ director recognises it and advises the track miles to run. Speed reductions and increased descent rates in jet aircraft don't work! Would it be possible to maintain aircraft speed and add another mile or two??
Ka Boy
You have speed brake, flaps, gear and your three times tables! Jet aircraft are perfectly capable of the adjustments you mention.
ATC controllers throw it back at the airlines and say you are trying to facilitate economies through track shortening and their pilots are incapable of coping. Pilot descent and speed management inside of 30 miles is woeful- I'm tired of sitting in trail behind HKG pilots dragging their aircraft in and being so low on profile the TAS differential becomes a factor in ATC separation.
It has become so endemic in HK airspace that I sit on a comfortable jet descent profile and get asked by ATC if I have sufficient track miles to run!
I suggest ATC talk to airline management and use simulators to assess the prevalence of this profile laziness.
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HKG Weather Reports
Why is the weather always reported to be much better than it actually is?
If I see something like, Few at 800, Bkn at 1600 on the ATIS, then it is likely totally under cast as I arrive. Usually I can take the vis and divide it in half. Last time I departed the vis was reported as 3.5 km and I could not see the departure end of the runway when we lined up for takeoff. That is not unusual, but rather typical.
I know about the reporter being on the ground and the weather we experience being in flight .. Bottom line is the weather is almost never, ever as good as reported.
Is there a bonus for reporting good weather or something?
If I see something like, Few at 800, Bkn at 1600 on the ATIS, then it is likely totally under cast as I arrive. Usually I can take the vis and divide it in half. Last time I departed the vis was reported as 3.5 km and I could not see the departure end of the runway when we lined up for takeoff. That is not unusual, but rather typical.
I know about the reporter being on the ground and the weather we experience being in flight .. Bottom line is the weather is almost never, ever as good as reported.
Is there a bonus for reporting good weather or something?
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Last time I departed the vis was reported as 3.5 km and I could not see the departure end of the runway when we lined up for takeoff.
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Gnad
I'm not sure what type you are flying but we really are concious that a lot of the newer types have difficulty in making a 3 in 1 (~5%) descent gradient outside of the IAF unless they have the speed right back early, which is not what we want.
By way of example, we have had several representations from operators that the CANTO arrival is just too steep from MURRY.
Now when we designed and tested it rigourously in the B777 sim, it worked well in several extreme wind scenarios, albeit at least 1/2-3/4 speed brake was required for much of the arrival until after SILVA. But we designed it close to the limit of what PANS-OPS allows and what we understood the operators wanted. With 42 track miles from 13000 its right on the money at 5.1%
It now turns out that the 330s and -8s ,to name a couple, really struggle, so we have taken steps to lower the crossing altitude at MURRY.
In line with recommendations from the FMS manufacturers, rather than a hard level requirement, you can expect to see a window of F110-130 at MURRY come into play in around May. We need to give the FMS coders 2 AIRAC cycles notice to get it in the box.
We had to do a fair bit of airspace reorganization to do that as there is quite a bit going on in the sector below up to F120.
Hopefully that will allow everyone to fly their desired profile in future.
P.S. I'm waiting fr Nitpicker330 to come on and tell me 130 isn't a problem. I assume he's on the 330! ;-)
By way of example, we have had several representations from operators that the CANTO arrival is just too steep from MURRY.
Now when we designed and tested it rigourously in the B777 sim, it worked well in several extreme wind scenarios, albeit at least 1/2-3/4 speed brake was required for much of the arrival until after SILVA. But we designed it close to the limit of what PANS-OPS allows and what we understood the operators wanted. With 42 track miles from 13000 its right on the money at 5.1%
It now turns out that the 330s and -8s ,to name a couple, really struggle, so we have taken steps to lower the crossing altitude at MURRY.
In line with recommendations from the FMS manufacturers, rather than a hard level requirement, you can expect to see a window of F110-130 at MURRY come into play in around May. We need to give the FMS coders 2 AIRAC cycles notice to get it in the box.
We had to do a fair bit of airspace reorganization to do that as there is quite a bit going on in the sector below up to F120.
Hopefully that will allow everyone to fly their desired profile in future.
P.S. I'm waiting fr Nitpicker330 to come on and tell me 130 isn't a problem. I assume he's on the 330! ;-)
Last edited by bekolblockage; 5th Mar 2014 at 23:19.
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bellcrank88
Yes, sorry for being slightly flippant there.
I guess psycho could give a better answer there being a tower guy.
I know that the ATIS update process is nothing like what I was used to years ago. Seems we are inexorably linked to HKOs METARs which I have to agree always seem to be on the optimistic side.
As SLF, its funny to see the contrast between travelling to BNE and returning to HKG. When the captain informs us at TOD that its a pleasant morning with clear sky, I know I can look out and see 100km down to the Gold Coast in BNE. Returning to HKG, it means I can just make out my flat in Tung Chung.
I guess psycho could give a better answer there being a tower guy.
I know that the ATIS update process is nothing like what I was used to years ago. Seems we are inexorably linked to HKOs METARs which I have to agree always seem to be on the optimistic side.
As SLF, its funny to see the contrast between travelling to BNE and returning to HKG. When the captain informs us at TOD that its a pleasant morning with clear sky, I know I can look out and see 100km down to the Gold Coast in BNE. Returning to HKG, it means I can just make out my flat in Tung Chung.
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BekolBlockage,
Is the driving factor before bringing in a change to a procedure the FMS coding? I understand that changes to an RNav procedure, with lateral changes, might need "it to be in the box". However changing a FL130 vertical constraint to a FL110-130 window could surely be done by Notam in the first instance, backed up by a plate reissue and finally by FMS coding. After all, anyone flying the 'old' procedure would still make the requirements of the window by being AT FL130.
Is the driving factor before bringing in a change to a procedure the FMS coding? I understand that changes to an RNav procedure, with lateral changes, might need "it to be in the box". However changing a FL130 vertical constraint to a FL110-130 window could surely be done by Notam in the first instance, backed up by a plate reissue and finally by FMS coding. After all, anyone flying the 'old' procedure would still make the requirements of the window by being AT FL130.
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I am based in HK and regularly fly in and out of HKIA.
With the increase in traffic operating in and out of HKIA recently, I have noticed that separation between us(a private jet) and larger jets is getting reduced.
We have encountered wake turbulence of varying degrees consistently when approaching runways 07L/R. On our last approach to 07L, ATC approach controller got us to with 5.6 NM behind a B777.
The answer to your question quickly is 5NM, so in the case you mentioned you were issued a precautionary warning only. So what is our practice or required? ATC is REQUIRED to provide WAKE TURBULENCE SEPARATION (WTS). For RWY 07 there are many reasons why it may deteriorate below the prescribed standard. Poor controller judgement, one or more crews not following directed speeds, strong tailwind on base and headwind on final. If this eventuates:
A following aircraft that is positioned with less than the required WTS can
1. be removed by ATC from the sequence and repositioned
or
2. The following crew SHALL be advised, "C/s.... you are 4.6nm behind a Heavy, caution wake turbulence". If deemed relevant, and there is still significant closure, the amount of closure is to be mentioned. ATC is passive in that we don't ask, but passively wait to see if the crew requests to carry out a missed approach, as is their right and seek re-positioning. To my knowledge this has not occurred here.
Whilst it is done rarely if ever here, if the following were to have the preceding in sight and accept visual separation and continue on a visual approach, then then all responsibility for wake turbulence can be handed to the crew. i.e. for an aircraft on a visual approach, the spacing with preceding traffic is the responsibility of the following aircraft.
Since everyone is using VNAV for descents, we are all following the same vertical profiles, and therefore the smaller aircraft like us, and many others, have an increase risk of more severe wake turbulence from the ever growing larger jets.
From extensive research undertaken to try to minimise WTS, aircraft following identical flight paths are unlikely to encounter wake. LIDAR radar typically depicts wake descending below the flight path of an aircraft for approximately 100' and then levelling off. So the wake is resting below glide path and gradually being moved downwind. Lateral movement has the wake propagate laterally at approximately 5 kts from either wing tip in still air. So if you descend in trail on the same ILS final, in headwind or crosswind conditions, a vortex encounter is improbable. If however, there were a quartering tailwind on final, the wake may advance towards the threshold and the possibility is quite real. At HKIA the greatest threat is on base leg where there is a possibility that if you are below the preceding, you will fly through the wake of that aircraft.
What are the minimum separations between small and large jets? Does ATC factor in this to their planning when smaller jets follow the larger ones?
Rather than small and large, we operate in accordance with international weight categories. Other than BA41 from GFS and the very occasionally BE20, HK operates Medium, Heavy and Super categories. So whilst some of the BAC traffic is at the bottom end of the Medium weight category, they are considered the same as a B737 or A320. The more likely position for encountering wake from a preceding is on base leg, or if you are positioned on final 07R and cross behind the traffic ahead for 07L. Wake on departure is a threat, but for business aircraft the climb profile is usually radically different than other traffic.
The standards are:
Medium following a Heavy - 2 minutes on departure - 5nm in trail when inbound or crossing traffic not 1000' above or below you.
Medium following a Super - 3 minutes - 7nm & 1000' applies
Heavy to heavy - not applicable - 4nm in trail & 1000' applies
Heavy following a Super - 2 minutes - 6nm in trail & 1000' applies
Medium crews remember 2 and 3 minutes (behind a Heavy & a Super) + 5 and 7nm in trail
Heavy crews remember 2 minutes (behind a Super) +4 and 6nm in trail.
Any intersection departure other than J10 or J2 add 1 minute to timed departure standards. Also, timing is done from take-off roll, not rotation or airborne.
ATC is regularly trying to find efficiency in traffic sequences to minimise delays. So traffic following an A380 may be positioned on the South runway as will BAC and Cargo arrivals. To make this effective, it permits the sequence to compress if traffic can be positioned to take advantage of it. IFR separation allows for traffic to be staggered North and South at 2.5NM. Under ideal conditions, TWR can accept visual separation between the two finals and permit simultaneous landings. Difficult to achieve on 07 because of the close base.
So as mentioned above, where the major threat is on base leg, if we run North/South landings, controller technique should be to have the preceding heavier aircraft as low as possible on base and then retain vertical separation (1000' above) until the following intercepts final and is clear of the flight path of the other aircraft. There is no WTS consideration between two aircraft on different runways at HKIA due to the physical displacement between them.
Also can we request increased separation from ATC and will they be willing to comply?
Consider how may airlines, different types and business aircraft that operate into HKIA. Other than international standards, what justification is there to arbitrarily increase spacing? The industry is crying out for predictability. If APP and TWR were to conduct a personalised Q&A with each aircraft they handle on what their preferences are, I think you'll understand how futile it would be. Especially when you are part of a sequence that spans more than one hour of continuous traffic, then as you are being positioned on base you request additional spacing behind the Heavy in front. How much? What are the consequences for other traffic? On departure if you are number one at the hold, you're given line up with an inbound landing on final and as you enter the runway you announce you require not 2 but 3 minutes separation with the preceding departure.
Would you consider asking in LHR, JFK or ATL? ATC operates to provide separation using international standards, not aircrew preference.
These same topics have been asked by many business crews. Thanks for submitting to allow a broader education on them.
With the increase in traffic operating in and out of HKIA recently, I have noticed that separation between us(a private jet) and larger jets is getting reduced.
We have encountered wake turbulence of varying degrees consistently when approaching runways 07L/R. On our last approach to 07L, ATC approach controller got us to with 5.6 NM behind a B777.
The answer to your question quickly is 5NM, so in the case you mentioned you were issued a precautionary warning only. So what is our practice or required? ATC is REQUIRED to provide WAKE TURBULENCE SEPARATION (WTS). For RWY 07 there are many reasons why it may deteriorate below the prescribed standard. Poor controller judgement, one or more crews not following directed speeds, strong tailwind on base and headwind on final. If this eventuates:
A following aircraft that is positioned with less than the required WTS can
1. be removed by ATC from the sequence and repositioned
or
2. The following crew SHALL be advised, "C/s.... you are 4.6nm behind a Heavy, caution wake turbulence". If deemed relevant, and there is still significant closure, the amount of closure is to be mentioned. ATC is passive in that we don't ask, but passively wait to see if the crew requests to carry out a missed approach, as is their right and seek re-positioning. To my knowledge this has not occurred here.
Whilst it is done rarely if ever here, if the following were to have the preceding in sight and accept visual separation and continue on a visual approach, then then all responsibility for wake turbulence can be handed to the crew. i.e. for an aircraft on a visual approach, the spacing with preceding traffic is the responsibility of the following aircraft.
Since everyone is using VNAV for descents, we are all following the same vertical profiles, and therefore the smaller aircraft like us, and many others, have an increase risk of more severe wake turbulence from the ever growing larger jets.
From extensive research undertaken to try to minimise WTS, aircraft following identical flight paths are unlikely to encounter wake. LIDAR radar typically depicts wake descending below the flight path of an aircraft for approximately 100' and then levelling off. So the wake is resting below glide path and gradually being moved downwind. Lateral movement has the wake propagate laterally at approximately 5 kts from either wing tip in still air. So if you descend in trail on the same ILS final, in headwind or crosswind conditions, a vortex encounter is improbable. If however, there were a quartering tailwind on final, the wake may advance towards the threshold and the possibility is quite real. At HKIA the greatest threat is on base leg where there is a possibility that if you are below the preceding, you will fly through the wake of that aircraft.
What are the minimum separations between small and large jets? Does ATC factor in this to their planning when smaller jets follow the larger ones?
Rather than small and large, we operate in accordance with international weight categories. Other than BA41 from GFS and the very occasionally BE20, HK operates Medium, Heavy and Super categories. So whilst some of the BAC traffic is at the bottom end of the Medium weight category, they are considered the same as a B737 or A320. The more likely position for encountering wake from a preceding is on base leg, or if you are positioned on final 07R and cross behind the traffic ahead for 07L. Wake on departure is a threat, but for business aircraft the climb profile is usually radically different than other traffic.
The standards are:
Medium following a Heavy - 2 minutes on departure - 5nm in trail when inbound or crossing traffic not 1000' above or below you.
Medium following a Super - 3 minutes - 7nm & 1000' applies
Heavy to heavy - not applicable - 4nm in trail & 1000' applies
Heavy following a Super - 2 minutes - 6nm in trail & 1000' applies
Medium crews remember 2 and 3 minutes (behind a Heavy & a Super) + 5 and 7nm in trail
Heavy crews remember 2 minutes (behind a Super) +4 and 6nm in trail.
Any intersection departure other than J10 or J2 add 1 minute to timed departure standards. Also, timing is done from take-off roll, not rotation or airborne.
ATC is regularly trying to find efficiency in traffic sequences to minimise delays. So traffic following an A380 may be positioned on the South runway as will BAC and Cargo arrivals. To make this effective, it permits the sequence to compress if traffic can be positioned to take advantage of it. IFR separation allows for traffic to be staggered North and South at 2.5NM. Under ideal conditions, TWR can accept visual separation between the two finals and permit simultaneous landings. Difficult to achieve on 07 because of the close base.
So as mentioned above, where the major threat is on base leg, if we run North/South landings, controller technique should be to have the preceding heavier aircraft as low as possible on base and then retain vertical separation (1000' above) until the following intercepts final and is clear of the flight path of the other aircraft. There is no WTS consideration between two aircraft on different runways at HKIA due to the physical displacement between them.
Also can we request increased separation from ATC and will they be willing to comply?
Consider how may airlines, different types and business aircraft that operate into HKIA. Other than international standards, what justification is there to arbitrarily increase spacing? The industry is crying out for predictability. If APP and TWR were to conduct a personalised Q&A with each aircraft they handle on what their preferences are, I think you'll understand how futile it would be. Especially when you are part of a sequence that spans more than one hour of continuous traffic, then as you are being positioned on base you request additional spacing behind the Heavy in front. How much? What are the consequences for other traffic? On departure if you are number one at the hold, you're given line up with an inbound landing on final and as you enter the runway you announce you require not 2 but 3 minutes separation with the preceding departure.
Would you consider asking in LHR, JFK or ATL? ATC operates to provide separation using international standards, not aircrew preference.
These same topics have been asked by many business crews. Thanks for submitting to allow a broader education on them.
Last edited by psychohk; 9th Mar 2014 at 14:14.
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ATIS
The ATIS can be disruptive to all concerned. ATC has to create it to accurately catch prevailing conditions. If these are changing rapidly you'll approximate and generally we will be pessimistic if it is done manually. That is, post the worst case scenario.
Accepted practice though is that the ATIS should be left in general to capture the METAR conditions and that is what is transmitted. We do at times conflict with MET and time permitting will manually scribe the differences. This over-rides the METAR.
There are laid down criteria for when and ATIS must be updated, but if there are only minor variations, the aim to minimise workload in ensuring everyone is on the current information and minimise the R/T loading, is to limit the updates to hourly where ever possible.
For arrivals on first contact with TWR, all traffic will be given an update on conditions that vary with the ATIS. As you can imagine if there is a CB active and it is moving, to keep this type of information precisely updated is not realistic. So reality is to post a generalisation and any significant detail on APP or TWR frequency as it occurs.
Accepted practice though is that the ATIS should be left in general to capture the METAR conditions and that is what is transmitted. We do at times conflict with MET and time permitting will manually scribe the differences. This over-rides the METAR.
There are laid down criteria for when and ATIS must be updated, but if there are only minor variations, the aim to minimise workload in ensuring everyone is on the current information and minimise the R/T loading, is to limit the updates to hourly where ever possible.
For arrivals on first contact with TWR, all traffic will be given an update on conditions that vary with the ATIS. As you can imagine if there is a CB active and it is moving, to keep this type of information precisely updated is not realistic. So reality is to post a generalisation and any significant detail on APP or TWR frequency as it occurs.