Centre Fix

[SkidSolo]

Tried a search but no joy.

I've heard it quite a few times and asked but nobody seems to know. I assumed it was the IAF or FAF. Is it somewhere in between i.e the centre!

Just wondered.

Ta.
SS

[HEATHROW DIRECTOR]

I used to hear some of my colleagues, who were commercial pilots as well as ATCOs, clearing aircraft to the "centre fix" - usually the straight-in approaches early in the morning at Heathrow - but I never did understand what it meant!

[ESSEX BOY]

I Believe its a 5 mile final ? or FAF ?

I Have also been asked to proceed to to the centre fix, thought maybe a military term as thats where I first heard it. However would be interesting to know a definitive answer !

EB :ugh:

[keithl]

Hold on, chaps, I'll need to look up chapter and verse for you, but Centre Fix is certainly not IAF, IF or FAF. I believe its an FMC term and I think there was an AIC about its use a while back, but a quick look failed to find it. I'll get back to you if no-one else beats me to it!

[expedite_climb]

As a pilot I undestand it as Centre(line) fix. As keithl alludes to; I would go direct to the first FMC waypoint on the centreline - probably in the region of an eight mile final - bu dependant upon the approach....

[BOAC]

To amplify the above - on the 737 FMC it appears as 'CF08' for a runway 08. I know not if it is a fixed distance, I assume it varies with each runway and I think it gives distance in which to 'establish' before the approach descent point.

NB: Nice controllers - as pilots we DO like direct clearance to it - from as far away as possible:D :D

[brimstone]

"Centrefix" is a waypoint used when a pilot is self-navigating onto an approach using the flight management system. There is no uniform definition of "Centrefix" and it may represent different positions when used by different aircraft operators or even different types used by a single operator. There are no formally promulgated procedures which use a "Centrefix".

Controllers have been given advice when dealing with aircraft proceeding to a "Centrefix"; namely, they should allocate levels in accordance with standard procedures; ensure they fulfill their responsibilities regarding terrain clearance; not initiate reference to "Centrefix" themselves; if in doubt ask the pilot to define the position of the "Centrefix" being used.

[DirtyPierre]

There is no uniform definition of "Centrefix"
I can just see it at the Board of Inquiry as Mr. Smug QC asks "and you told him to track to the , ahem, Centrefix, Mister DP. Where exactly is that?"

[DFC]

brimstone has it spot on.

Often at about 8 miles but it can vary as explained.

ATC seem to prefer to say "route direct to an 8 mile final" in some places while others still use the term centrefix.

Using the "8mile final" removes the doubts DirtyPierre talks about.

Regards,

DFC

[3Greens]

i can confirm that having had a quick look at pans-ops there is no definition of a centrefix. only IAF,IF,FAF.

[BALIX]

The word 'centrefix' started being used when Rnav became widespread. Almost as soon as it was common, we received a MATS Part 1 SI instructing us not to use the term as it is too vague and might mean different things to different operators.

Instead we should specify an '8 mile final', though you may hear the phrase 'eight mile centrefix'.

In effect, though, if I were to tell you to route direct to the centrefix for 24 at Edinburgh, I'd be pretty confident as to the route you were going to follow. If your specific centrefix is anywhere between a five and ten mile final isn't going to make a great deal of difference to an area controller. Approach control may well be a different matter which is why you might be asked by the TMA controller to 'report your routing' to the approach controller.

[Flying Fiona]

Ask the Mytravel boys. The CAA authorised them about 8 years ago to trial this procedure. It was scrapped because of poor track keeping.

The centre fix was a point on the centre line at a defined distance of 8 miles.

The problem was that some of the RNAV equipment that they were using was not accurate enough at the lower levels which resulted in track excursions.

[eastern wiseguy]

Balix is correct.It matters not a lot to him where he sends the aircraft to,but as an approach controller it matters a LOT to me.I will approve a routing to an(e.g.) 8 mile centre fix approach to Runway 25...or any range of final that the crew want. This has the obvious caveat that whilst you may like it I may have to restrict your turns as I am effectively giving you carte blanche to manoeuvre all over the TMA to get there.I believe that this was the reason SRG specified ATC insistence on a range of final rather than centrefix.

Also to BALIX ...a number of aircraft come over on the Belfast sector cleared to a "centrefix" and promptly ask for vectors! I have told them if they don't want it..just say no!!:ok: :ok: