Cleared to the CentreFix

[EGCC Rwy 24]

All to do with self navigation, using FMS - I know that much. But, is the CentreFix a specific point on the extended centreline, and if so where? Different DME for each runway? If it's all up to the pilot, and not a fixed point, how does the controller know what the pilot is going to do?

Cheers.

[PPRuNe Radar]

ATC in the UK are not allowed to use the term 'Centre Fix' for precisely the reasons you state. We can however clear people direct to 'a X mile final'.

The actual position of the CF will vary depending on aircraft type, coded position in the FMS database if any, or where the pilot places the CF if it's a self constructed procedure.

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PPRuNe Radar
ATC Forum Moderator
[email protected]

[This message has been edited by PPRuNe Radar (edited 12 November 2000).]

[niteflite01]

Ooooops!!!!

I know some of my more renegade-like "R" colleagues at Manch use direct centre fix alot, especially for 24 when it's deathly quiet (doesn't happen alot seemingly these days!) http://www.pprune.org/ubb/NonCGI/frown.gif

I of course, wouldn't do such a thing http://www.pprune.org/ubb/NonCGI/tongue.gif

I always presume that the aircraft is going to position for about a 10 mile final.

Guess we shouldn't rely on such suppositions though. It is only used when it's really really quiet and everything is bandboxed.

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"Go around..I say again...go around"


[This message has been edited by niteflite01 (edited 11 November 2000).]

[EGCC Rwy 24]

Indeed Niteflite, it was yesterday evening at EGCC that prompted me to ask the question! It was quite late and deathly quiet. From memory it was a BA A319 from Gatwick (in itself a tad unusual for that not to be a 737), as soon as he popped up on 119.4 "towards Trent" he was cleared direct to the Centrefix 24R - the pilot's voice in the readback seemed to show some surprise at the clearance.

Interesting that although no further headings were given, ATC were still very much in charge of the altitudes.

Still, at least I now know it's pretty much as I thought in terms of distance etc.

Next stop, an FAQ section for my site I think!!

Cheers both.

[No speed Restriction]

As far as I am concerned routeing aircraft direct to a centre fix is not a problem, be it 6 mile final or 12. Any ATCO who bases any form of separation on this aircraft NOT locked on a heading would be damn silly. In reality roueting these aircraft to this "generic" spot in space is no less hazardous than sending them to a reporting point outside your area of responsibilty as the difference between a 6 mile final and 12 mile final will result in virtually identical headings. I often use direct cfix R24 right at manch when it is quiet, this to me seems to be the most expeditious route that can be offered for all parties concerned. The reason your A319 may have been a little puzzled is only because it isn't offered as a matter of course except late at night. Hope this helps NsR

[No speed Restriction]

The fact that a centre fix is not a consistent point in space is relatively academic as the use of "route direct cfix rwy24r" is only used during the quieter periods. When you consider that one cfix maybe at 8 miles and another operators could be at 12miles on the extended centreline what difference does it make? It is no worse than sending an aircraft to a beacon outside your area of responsibilty, I defy any ATCO at manchester to know "exactly" where an aircraft will go if you send it to Midhurst for example.... this is not considered to be a problem and any ATCO who then uses track separation without locking the aircraft on it's heading would be daft. I use the roueting to centre fix as a matter of course when it is quiet and this has to be the most expeditous route for all concerned. Your BA crew may have been surprised purely by how early the route was given, ask any charter crew who operate late at night and "direct c-fix" is certainly more likely to be the norm.

Long live the centre fix ( wherever it may be !!!)

NsR

[10W]

We tend to use 'direct 8 mile final Runway 05/06/23/24' as a standard in the Scottish TMA. If the pilot wants something else then he normally says so (some turboprops seem to like 6 miles for example).

Not only do we know where the pilot is aiming for, it keeps us squeaky clean with SRG as well.

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10 West
UK ATC'er
[email protected]

[No speed Restriction]

OOPs mulitiple posts...why does that happen

sorry for two ...bloody computers hehe

[SAM 2M]

There is or certainly used to be a section on the Manual of Air Traffic Services dealing with the Centre Fix.

[cossack]

MATS Pt 1 SI 6 of 99
The use of FMS waypoints to assist aircraft approaching an aerodrome.
Quote:
"It is not the intention of this insruction to prevent controllers from permitting pilots to self position to final approach. However, in authorising this manoeuvre, controllers should bear in mind that the vertical and horizontal profile the aircraft will fly is not completely predictable and, therefore, should exercise the same caution they would when approving a visual approach."

"...the Authority requires controllers to adhere to the following rules when approving use of such approaches:
1 Aircraft are to be allocated levels in accordance with MATS Pt 1 and 2.
2 Controllers, especially those providing a radar service, are reminded of their responsibilities with regard to terrain clearance...
3 Controllers are not to initiate reference to "Centrefix" or other locally used terms.
4 If controllers are in any doubt about the location of the "Centrefix" or other position referred to by a pilot, they are to ask the pilot to define this position and take this definition into account when carrying out their controlling duties."

All bases covered, take care now!

[EGCC Rwy 24]

And I was expecting a simple answer that would probably have made me look silly for not knowing in the first place!

Wow!!!!