CFMU / Sector Occupancy

[UAC48]

Hello All,

In the CFMU sense, what is the definition of the "sector occupancy" (number of a/c by sector team) ?

Only a/c on r/t, or "a/c on r/t + a/c coordinated", or something else...

Happy to read you,

[BrATCO]

Basically, "occupancy" is a number of aircraft at the same time in a sector. In a way, that's the number of aircraft on the sector's frequency at the same time.

You can also have aircraft in your sector, not on your frequency. Were they "expected" (by CFMU) in your sector or not ? You can also have aircraft on your frequency, outside your sector...

What's the purpose of your question ?

Do you wish to know how to "calculate" an "occupancy" ?

[Lon More]

The EEC document Hourly entry vs. occupancy count definitions and indicators (http://www.eurocontrol.int/eec/gallery/content/public/document/eec/report/2007/015_Hourly_entry_vs_occupancy_count_definitions_and_indicato rs.pdf) may help (or at least solve insomnia)

1.2.1. Definition
Occupancy Count named OCC8 for a given sector is defined as the number of flights inside the sector during a selected Occupancy Count time period. This selected Occupancy Count Time period is referred as Occupancy Counting Period.
This Occupancy Counting Period is defined in terms of a Step value and duration value as a picture taken every Step value with an exposure of the Duration value:
• The Step value defines the time difference between the start time of two consecutive Occupancy Counting Periods.
• The Duration value defines the time difference between start and end time of each Occupancy Counting Period.

[UAC48]

Thank you, Lon More and BrATCO for your fast replies.

EEC document is a near to be perfect reply at my ask. Found it in the morning is a guaranty for the next night ;)

I have made a first diagonal lecture of this document and almost all what I need is provided... Great !

But, I have another conceptual ask...

For a done CFMU 60/60 rate, what's the better way to simulate traffic :
(red value are time of entry in seconds from start)

A) an entry every 60 secs during an hour (surely not, but that's simple to explain...):
i.e.
0 (+ 60) 60 (+ 60) 120 (+ 60) 180...

B) an entry randomly between every 0 to 120 sec during an hour
i.e.
0 (+ RANDOM(0 to 120)=35) 35 (+RANDOM(0 to 120)=105) 150 (+RANDOM (0 to 120)=75) 225 ...

C) the first version with a random shift on each value
i.e.
0 (+ 60=60 + RANDOM) 55 (+ 60=120 + RANDOM) 134 (+ 60=180 + RANDOM) 155...

Or any else.....

Thanks again,

[Lon More]

I think by taking an hourly rate you are making things unneccessarilly complicated. "Bunching" will have a much greater effect. This is probably one of the main reasons we use 20 minute periods. ( at least, we did, a few years ago. Things may have changed now)

[UAC48]

Hello "Lon More",

And thank you for your reply.

The problem, i.m.h.o., is the same with a 20 minutes based rate...

Let use a 20/20...

Did you may expect a "regular" entry traffic (1 each minute)... surely not at all...

So, what is the amount of "unregulation"...

May you expect all your a/c enter in the first 5 minutes than no more traffic enter after...

Or is it another "sub regulation" in order to avoid those bunch...

[Lon More]

Theoretically with a 20/20 rate you could get all the traffic in one minute, this should be workable in most sectors. However, with a 60/60 rate, should they all come in one minute I think it would be a 4 aspirin headache :uhoh:

as I said earlier, no longer my headache though;)

[UAC48]

Please, let two aspirins for my own headache :rolleyes:...

Difficult to found the right balance between various systems...

The best I've found was a random value between the half of seconds/aircrafts and one and half seconds/aircrafts...

With a 60/60 or 20/20 rate, that's give a random value between 30 secs and 90 secs between entries...

:ugh:

[Token Sane Person]

UAC48, it sounds like you are trying to write a traffic generator to produce traffic at a specified rate.

In theory I believe the "right thing" is an exponential distribution for the arrival intervals. See Poisson process - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Poisson_process) for more details.

However if you plug in an arrival rate into this process, it will only give you that arrival rate on average; if you specify 10/20 then on average you will get 10 aircraft in 20 minutes, but in any given 20 minute slot you might get more or you might get less. If you want to have a 20 minute exercise where exactly 10 aircraft arrive then generate 10 random numbers in the range 0-20 and use those for the arrival times.

Is that what you wanted to know?

[UAC48]

Is that what you wanted to know?

Exactly... This topic may be close, now :)

Thanks to all for your help !

[UAC48]

Again on little detail... Ask is for a MUAC ATCo...

At Maastricht what calculation method is used for occupancy ? (aircraft state + times of step and duration)

Thanks again,

[UAC48]

Help... Somebody...

Thanks...

[Lon More]

I'm retired now so have no access to the data any more; however Google "maastricht UAC sector load calculation" and that should provide more than you need.


BTW what's it for VATSIM?

[UAC48]

If I post a request on a forum, that's always after a serious numbers of unresult researches elsewhere on the web... and not only on Google...

From my own tests, it seems they use a step of 5 mins with a duration of 5 mins... But I want to check if my conclusions are good.

I dont understand the link with VATSIM... That's in effect for simulation, but not in network...

Thanks again,

[Lon More]

Have you tried contacting the UAC directly:
Email: [email protected]
Phone : +31 43 366 1306
Phone : +31 43 366 1352



or phone Haren directly, more chance of an answer in French:
For information about EUROCONTROL or air traffic management in Europe:
Tel: +32 2 729 51 51
[email protected]