ILS Training
02-18-2009 | 01:21 PM
#11
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From: Legacy FO
Pilot Contoller Glossary:
FINAL APPROACH FIX- The fix from which the final approach (IFR) to an airport is executed and which identifies the beginning of the final approach segment. It is designated on Government charts by the Maltese Cross symbol for nonprecision approaches and the lightning bolt symbol for precision approaches; or when ATC directs a lower-than-published glideslope/path intercept altitude, it is the resultant actual point of the glideslope/path intercept.
Notice, the PCG mentions where the FAF is if ATC clears you to intercept the glidepath below the published Glideslope Intercept Altitude. However, it does not mention if they clear you the approach and you are above the published Glideslope Intercept Altitude.
In this case, you *should* fly the approach (using non-precision methods) to comply with published minimum, maximum, or hard altitudes --- the Glideslope may not comply with these restrictions. Additionally, the gideslope at most airfields is only good (and flight checked) to a distance of 10NM. If you intercept the glideslope from a high altitude, you run the risk of intercepting a false glideslope.
-Fatty
FINAL APPROACH FIX- The fix from which the final approach (IFR) to an airport is executed and which identifies the beginning of the final approach segment. It is designated on Government charts by the Maltese Cross symbol for nonprecision approaches and the lightning bolt symbol for precision approaches; or when ATC directs a lower-than-published glideslope/path intercept altitude, it is the resultant actual point of the glideslope/path intercept.
Notice, the PCG mentions where the FAF is if ATC clears you to intercept the glidepath below the published Glideslope Intercept Altitude. However, it does not mention if they clear you the approach and you are above the published Glideslope Intercept Altitude.
In this case, you *should* fly the approach (using non-precision methods) to comply with published minimum, maximum, or hard altitudes --- the Glideslope may not comply with these restrictions. Additionally, the gideslope at most airfields is only good (and flight checked) to a distance of 10NM. If you intercept the glideslope from a high altitude, you run the risk of intercepting a false glideslope.
-Fatty
02-18-2009 | 01:23 PM
#12
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From: A320 Captain
He may have been referring to this without knowing it. He may have meant to say final approach segment. Think in terms of visibility and when you can continue the approach. At ORD, they will sometimes put you on a 20 mile final and the visibility could be rapidly changing. Lets say you are on that 20 mile final and the vis goes to zero. Can you continue the approach? Yes you can if you are on that approach final segment.
As far as the FAF, I think the previous guy is correct when he said its the intersection of the final approach course and the FAF altitude...depicted by that little lightning bolt.
I hope I'm not spreading incorrect info...someone correct me if I'm wrong. I've been out of the 121 world for about a month already!
As far as the FAF, I think the previous guy is correct when he said its the intersection of the final approach course and the FAF altitude...depicted by that little lightning bolt.
I hope I'm not spreading incorrect info...someone correct me if I'm wrong. I've been out of the 121 world for about a month already!
02-18-2009 | 01:28 PM
#13
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The final approach segment for an approach with vertical guidance or a precision approach begins where the glide slope intercepts the minimum glide slope intercept altitude shown on the approach chart. If ATC authorizes a lower intercept altitude, the final approach segment begins upon glide slope intercept at that altitude.
02-18-2009 | 01:37 PM
#14
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02-18-2009 | 01:58 PM
#15
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well you can intercept the glideslope and follow it down from any assigned altitude. there is no reason to always go down to the published alt. it is jsut a matter of establishing a point in space where your FAF is and that point would be at the alt published and glideslope.
IJ
IJ
02-18-2009 | 02:10 PM
#16
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Just to add, there are a few approaches where, if one intercepts the glideslope prior to the published intercept location, the aircraft will be below mandatory minimum crossing altitudes. I believe LAX and CVG have approaches that have this characteristic.
02-18-2009 | 02:22 PM
#17
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Correct...and I believe the ILS 4R into ORD is one of these cases as well. You can absolutely follow the GS outside the FAF, just be sure that you are at or above those hard altitudes. I think you miss one or two of the outer hard altitudes by a couple hundred feet if you strictly follow the GS.
02-18-2009 | 03:01 PM
#18
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From: CRJ-700 Captain
I have to disagree to the timing. You do not fly an ILS to a time reference. Nor would starting the time at GS intercept work as this is typically prior to the LOC only FAF. If I am inside the FAF for an ILS and I lose GS, I am executing a missed approach. I was not cleared for the LOC approach. I did not brief a LOC approach. I will miss the approach, confer with ATC, and either return for the LOC only approach, an entirely different approach, or I will divert to my alternate. Of course if I were in an emergency situation, all bets are off and I might well consider a loc only approach. As for time, I call for time to start over the outer marker or FAF, not at GS intercept
02-18-2009 | 03:03 PM
#19
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From: Legacy FO
As you guys pointed out, the Glideslope does not guarantee altititude restrictions outside the FAF. Additionally, it may not be flight tested (you may get interferrence or abnormal indications). Don't confuse being told to join the localizer with an approach clearance. If you are arming the ILS to follow the localizer inbound to meet the alititude restrictions, I would say you are in violation because the aircraft isn't going to stop at the FAF altitude (remember, you weren't cleared the approach). At my company, we don't arm the ILS unless you are cleared the approach.
-Fatty
-Fatty
02-18-2009 | 03:10 PM
#20
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From: doggy style
He was correct. In fact, either way is correct. However, it is more proper to intercept the glideslope at your current altitude rather than to take a step-down approach to it. It is more fuel efficient and safer to a degree.
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