Reciprocal departures 150NM apart

[karim5sd]

Hi everyone,

Iam undergoing ACC procedural training, I have a doubt regarding two reciprocal departures which are 150 NM apart, requesting clearance from ACC, kindly provide the solution.

Scenario:

150NM. 100NM. 50NM. 0 NM
W20 •-------------•------------•-------------• W20
BPL. LIMA. BAMUL. CCB.

XYZ456. ABC123
Req FL250. Req FL240

BPL------VOR
LIMA-----Waypoint
BAMUL---Waypoint
CCB------VOR

XYZ456 will route via W20 east bound
ABC123 will route via W20 west bound
Both are requesting clearance at the same time

[Plazbot]

All depends on your state's established standards. If you want pure ICAO 4444, It is pretty much that they have passed by the applicable longitudinal standard that you would apply if they were following each other.

eg 10 DME,
5.4.2.3.2.4 Aircraft on reciprocal tracks. Aircraft utilizing
on-track DME may be cleared to climb or descend to or through
the levels occupied by other aircraft utilizing on-track DME,
provided that it has been positively established that the aircraft
have passed each other and are at least 10 NM apart, or such other
value as prescribed by the appropriate ATS authority.



80 RNAV,
5.4.2.5.7 Aircraft on reciprocal tracks. Aircraft utilizing
RNAV may be cleared to climb or descend to or through the
levels occupied by other aircraft utilizing RNAV provided it
has been positively established by simultaneous RNAV
distance readings to or from the same “on-track” waypoint that
the aircraft have passed each other and are at least 150 km
(80 NM) apart


RNP
5.4.2.6.3.4 Aircraft on reciprocal tracks. Aircraft may be
cleared to climb or descend to or through the levels occupied by
the other provided that it has been positively established that
the aircraft have passed each other and the distance between
them is equal to at least the applicable separation minimum


For before, you only have 10 minutes prior to time of passing.

5.4.2.2.3 Aircraft on reciprocal tracks. Where lateral
separation is not provided, vertical separation shall be provided
for at least ten minutes prior to and after the time the aircraft
are estimated to pass, or are estimated to have passed (see
Figure 5-20). Provided it has been determined that the aircraft
have passed each other, this minimum need not apply.

4444 Chapter 5 refers.

So the answer to your question is to establish some form of vert sep 10 minutes before time of passing then the rest after established passing.

The other option would be to depart one on track and the other on a radial stepping whoever got away second under the first until the radial/track diversion was outside the applicable distance then direct after vert established

eg

VOR 15degrees/15nm
NDB 30 degrees/15nm
Dead Reckoning 45 degrees/15nm

After that you gotta start drawing things to establish the overlap of protected airspace based on RNAV perormance.


Procedural control, like helicopters is hocus pocus. Run away now.

[qwerty2]

What happened to the old procedure of climbing at NOT MORE or NOT LESS than a specified rate?
I only used it once on a DanAir Comet and a BUA 1-11 but it works.
Launch the traffic to the higher level first specifying a minimum rate of climb build in a buffer then launch the second at a lesser rate thereby holding vertical throughout the climb.
We even had strip marking for that...ahh nostalga

[topdrop]

Best way is to give a clearance limit to the lower aircraft (ABC123), calculate the lat sep based on holding at that point. Give other aircraft a requirement to reach a level above by lat sep point. Trick is to make the clearance limit at a point that ABC123 will never have to hold. i.e. XYZ456 reaches the lat sep point before ABC123 reaches clearance limit, at which time you can cancel the clearance limit.
I know a lot of places don't teach use of clearance limit (and calculation of lat sep for a clearance limit), so the next best choice is use of diversion radial as per Plazbot's post.

[Plazbot]

The clearance limit idea is a novel one but would not save much over the 10 minutes prior to time of passing as an enroute aircraft must be vertically separated from a holding aircraft 5 minutes prior to entering the protected area of the holding pattern. The over shoot and dead reckoning turn plus nav buffer would end up being something like 3 minutes so you would get I guess 8 minutes prior to time of passing but is enormously workload intensive. You can also vertically separate from a holding aircraft by a point as determined by an ATC provider and listed in local procedures so if your State dictated that LIMA was a hold and BAMUL was clear of that you could instruct the 'leftbound' aircraft to reach the higher level by BAMUL with the 'rightbound' aircraft instructed to hold. Again, this is dependent on your specific country and their rules outside of doc 4444.

5.5.2 Except when lateral separation exists, vertical
separation shall be applied between aircraft holding in flight
and other aircraft, whether arriving, departing or en route,
whenever the other aircraft concerned are within five minutes
flying time of the holding area or within a distance prescribed
by the appropriate authority.

[Plazbot]

qwerty, that was standard rate 1000 feet per minuite and the last 1000 feet at 500 fpm or something similar. They removed it from the book I learnt from many years ago.I sued it once and neither pilot had any idea what I was talking about. Not an ICAO procedure. You can only assign a vacated level using the assurance of not losing 1000 feet requiring reports.

5.3.4.1 An aircraft may be cleared to a level previously
occupied by another aircraft after the latter has reported
vacating it, except when:
a) severe turbulence is known to exist;
b) the higher aircraft is effecting a cruise climb; or
c) the difference in aircraft performance is such that less
than the applicable separation minimum may result;
in which case such clearance shall be withheld until the
aircraft vacating the level has reported at or passing another
level separated by the required minimum

To the topic starter, I assume you are doing your training in India. Are you a pure doc 4444 country there?

[karim5sd]

Plazbot, Yes am from India & India follows DOC4444, thank you for your valuable suggestions, what we are doing here is suppose XYZ456 departs first & XYZ456 requesting FL250 with rate of climb 1000fpm, ABC123 requesting FL240, instruct XYZ456 to climb to FL250 maintain with rate of climb 1000fpm & ABC123 to climb to FL240 with rate of climb 1000fpm or less, my doubt is whether this clearance provides standard separation

[UpperATC]

qwerty2 did you mean the;

6.3.1.1
Clearances for departing aircraft shall specify, when necessary for the separation of aircraft, direction of take-off and turn after take-off; heading or track to be made good before taking up the cleared departure track; level to maintain before continuing climb to assigned level; time, point/and or rate at which a level change shall be made; and any other necessary manoeuvre with safe operation of the aircraft.

For example:

Tower from the East calls and gets:
"ABC123 cleared FL250 - condition ROC 1000ft/min or more."
and condition for the tower - departure not later than 1200 UTC (for example)

Tower West gets:
"XYZ456 cleared FL240 - condition ROC 1000ft/min or less."
and condition for the tower - departure not before 1203 UTC.

Of course the vertical profile of the SID ( if any ROC are specified there) shall not be overlooked - the acft performance as well. And it would be probably better to initially give a lower level.

Maybe only for the "procedurally clean" answer in a written exam... :)

(however like qwerty2, I was using ROC conditions also, but in TMA with TWR environment, dealing with lower levels and shorter "routes"...)

[Russell Kaymer]

Karin, there is nothing in 4444 chapter 5 that would make the technique you mention allowable.

[UpperATC]

And Karim, please keep us updated - what your OJTIs or EXAMrs' have to say about this.

[topdrop]

must be vertically separated from a holding aircraft 5 minutes prior to entering the protected area of the holding pattern.
They only have to meet the requirement to reach by the lat sep point, not 5 mins before. (unless you're in Melbourne:):))

[Plazbot]

We are talking pure ICAO as opposed to OZ rules here. 5 minutes or a published point.

[blissbak]

Not later is normally told as "clearance expires"

[karim5sd]

Hi upper ATC, as per our instructors, suppose XYZ456 departs first clear it to FL250 with instruction maintain rate of climb say 1000fpm or more & clear ABC123 to FL240, with rate of climb 1000fpm or less, by this ABC123 will never get through the level of XYZ456 and vertical separation will be there .

[Plazbot]

In short, unless your country has rules to the contrary (of 4444) your instructors are talking ****.