IAFs and FAFs?

[Lump Jockey]

Hi all, first posting this year, so here goes! I was wondering if one of you pro's could explain to me what and how and when Initial Approach Fixes and Final.A.Fs are used. (Esp. the what are they bit!)
Secondly, are there just the 4 IAFs at LHR? (BIG, EPM, BNN, LAM)?
And lastly, what does the circular symbol made up of 3 rings of "+" mean? like the Chiltern one near Bovingdon?

[tori chelli]

LJ

an Initial Approach fix (IAF) is the fix of an instrument approach at which the aircraft leaves the en route phase of operations to commence the approach...so falls off the STAR onto the approach plate

an Intermediate Approach Fix (IF)is the fix at which an aircraft enters the intermediate approach segment. THAT is either the segment between the IF and the Final Approach Fix, or (more usefully) between the end of a reversal, racetrack, or dead-reckoning track and the Final Approach Fix....basically when you're lined up on the final approach track.

The Final Approach Fix (FAF) is segment of an instrument approach in which alignment and descent for landing are accomplished...i.e. when the final approach track intercepts the (nominal) glidepath.

as to the circles, do you mean the three rings made up of dots, in which case it's an NDB (CHT is an NDB) or a circle with a + in it which is a Visual Reporting Point (VRP)

BNN EPM LAM OCK would be IAF's as the STARs finish there and the approach plates start there. Spookily, the EGLL AIP entry AD2 EGLL 7-7 entitles the plate "Initial Approach Procedures".

Who says the system doesn't work?:D :D
Tori

[Lump Jockey]

From "spookily", I'm lost!!!!!!!!!!!!! In English plzzzz...:o

So, if I've understood right now, which I doubt, the STAR ends at the holds for LHR? Is that a correct assumption? Then the pilots revert to their approach charts/plates? Help plzzz....:o

[Gonzo]

Lump Jockey, yes, the STARs end at the holds for which they're named, ie all the LAM STARs end at the LAM hold.

Gonzo.

[DrKaos]

LJ,

Just to go one step further from Gonzo (don't ya miss me mate?), the STAR clearance limit is the beacon for the hold. Unless otherwise instructed, a/c will enter the holds. Aircraft are then sequenced from the holds onto final approach by the Directors. At Heathrow, the pilots don't start the approaches themselves. There are published procedures in AIP that Tori mentioned, however these would only be used in the event of an a/c in the hold who has experienced a radio failure(or a total Radar failure, in which case it would be kinda interesting to see what happens).

Hope this helps!

[Gonzo]

For me to miss you would imply I actually liked you in the first place! :D

Gonzo.

[Lump Jockey]

Thanks guys, you know I'm only an enthusiast at best, so all this is really great, and useful too! Thanks for the time taken for your replies!:)
Following on though, if the (LAM? STAR) ends at the LAM hold, which it does obviously, then where abouts and how far out does it start/begin, geographically would help too! And what's an AIP? (something something procedure no doubt?)
I've seen on charts for the respective holds/approaches that there's a 222 degree track from the BNN hold for a 09L arrival. Do planes follow this or is this what we're talking about if there's a failure of some description? Or does the ATCO use this as a guide as such?
And that symbol I talked about does seem to be made up of 3 circles of "+" if you look very closely, othwerwise it appears to be dots as you said, is that a normal VOR?
Thanks for your help!
LJ

[tori chelli]

L J

sorry, I thought you were a pilot. The AIP is the "Air Pilot" whuich is the bible for flying in the UK. The reference was to a section dealing with Heathrow (code EGLL).

The hold is based overhead the LAM beacon and is a racetrack turning 180 degrees away from the beacon, going straight for 1 minutes' flying time, then turning back towards the beacon and flying back (nominally) 1 minute until overhead, and then doing it all over again!

I haven't got a BNN chart in front of me, but I suspect the 222 degree line would be the track flown by an A/c following the radial from the BNN VOR. As DrKaos said, these procedures are designed to be flown by the pilot in the event of NO radar vectors from ATC (typically radar or radio failure). The radar vectors chosed by the ATCO would be similar to the non-radar pattern, but changed tactically to fit into the traffic sequence.

As to the symbol, it depends which chart you're looking at. Usually the NDB is circles of dots. A VOR is a hexagon and a VOR/DME is a hexagon in a box with a dot in the middle.

The NDB just sends out a signal in all directions and the needle in the cockpit points to it (hence Non Directional Beacon). The VOR sends out a pair of beams by which the equipment in the cockpit can detect it's displacement from any one of 360 tracks out (called radials). Dial up the radial you want and the needle says "fly left/right" until you're on it. Combined with DME (distance measuring equipment) you get what mathematicians call a polar coordinate...a point a known distance on a known bearing from a fixed origin.

I didn't realise I remembered so much of this crap :D :D

Tori