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joker64
1st Jun 2002, 17:58
I was taught, and have always taught that on an ILS approach the FAF is glideslope intercept. No matter what altitude you are at, or distance from the airfield.....it's glideslope intercept.

I've recently been challenged. Our Operations Manual requires landing configuration at the FAF. In Europe we frequently find ILS final approach segments from 15-20 miles. This makes our requirements a bit annoying for the controlers.

US government pubs annotate the FAF on an ILS approach with a lightning bolt, but Jeppesen defines it as glideslope interecept. I have yet to locate the general definition in Europe (as I know that each country has it's own regs).

Any input?

Hew Jampton
1st Jun 2002, 18:29
FAF is wherever the instrument approach procedure designer decides, basing the decision on ICAO design procedures etc. Could be G/S intercept, the OM or a DME distance. Marked on Aerad (UK) charts with a cross, although the chart publisher, Aerad, Jepp etc don't decide (or shouldn't decide), it's down to the procedure designer.

RadarContact
1st Jun 2002, 22:51
In Europe, the FAF is usually defined over the marker/locator or at a certain DME fix (around 4DME from touchdown).

Non precision approaches usually have them at the final descent point, which would correspond to the glide interception on an ILS.

quid
4th Jun 2002, 19:37
In the US, it's a little different.

On a precision approach, the FAF is where the published g/s intercept altitude intersects the g/s. No matter how high you get established on the g/s, you are not at the FAF until you reach that point. If you're using Jepp charts, it's the "notch of the feather" on the profile view.

For a non-precision approach, it's the Maltese cross.

If you're using US Ops. specs., it's important to know where the FAF is. Some requirements change once you've arrived at the FAF.

Captain Airclues
4th Jun 2002, 21:17
Under ICAO, there is no such thing as a FAF on an ILS approach, as a FAF is only applicable to a Non-Precision Approach. There is a FAP (Final Approach Point). which is where the final approach altitude intercepts the glideslope. The FAF 'cross' is often shown on ILS charts, but this is for the case of a Localiser Only approach, which is a Non-Precision Approach.
ICAO PANS-OPS states that, on an ILS Approach, the glideslope must be checked at 'a point equivalent to the position of an outer marker'. This is now normally defined by a DME fix, and is normally at about 4 miles from the runway.

Airclues