Knowing the Right Altitude to Capture the Glideslope?

[sd_flyer 6,023]

 

In reality you cannot just wander around the sky under instrument conditions trying to find a place to land. Either you are under the control of ATC or you are flying a published approach. 

 

Perhaps you mean published SID? ATC can't grant unpublished instrument approach unless it's an emergency ex. no gyro approach.

 

 Once I had an alternator failure and 20 minutes of battery life (estimated) in IMC. ATC squeezed me inside FAF to intercept ILS for the priority approach (kind of emergency but not in legal sense).

[Bobsk8 12,489]

Perhaps you mean published SID? ATC can't grant unpublished instrument approach unless it's an emergency ex. no gyro approach.

 

 Once I had an alternator failure and 20 minutes of battery life (estimated) in IMC. ATC squeezed me inside FAF to intercept ILS for the priority approach (kind of emergency but not in legal sense).

 

A SID is a departure procedure, not an approach procedure. 

[sd_flyer 6,023]

A SID is a departure procedure, not an approach procedure. 

 

Yes in this context I meant STAR. SID and STARS can't be excluded from the flight plan (if you are not  RNAV equipped). However, DP procedures are mandatory because some of them have "minimum required rate of climb" 

[Slayer 190]

Yes in this context I meant STAR. SID and STARS can't be excluded from the flight plan (if you are not  RNAV equipped). However, DP procedures are mandatory because some of them have "minimum required rate of climb" 

 

SID and STAR are given by ATC, you can request what you want but ultimately it's their call.

 

Also SD _flyer is correct about the Lightning bolt...I think someone owes an apology

 

The ILS glide slope is intended to be intercepted at the published glide slope intercept altitude. This point marks the PFAF and is depicted by the “lightning bolt” symbol on U.S. Government charts.

[sd_flyer 6,023]

SID and STAR are given by ATC, you can request what you want but ultimately it's their call.

 

 

 

If we are talking about real world. Not quite. Ultimate call is by pilot in command not ATC. ATC can't enforce pilot to make approach that his/her is not capable to do.  It also applies to SID and STARS

[Bobsk8 12,489]

If we are talking about real world. Not quite. Ultimate call is by pilot in command not ATC. ATC can't enforce pilot to make approach that his/her is not capable to do.  It also applies to SID and STARS

 

That is strange, you have many aircraft on a star coming into an airport like Atlanta, and some pilot can say he doesn't like that particular star and demands another one instead????   

[ryanbatc 12,770]

SID and STAR are given by ATC, you can request what you want but ultimately it's their call.

 

Also SD _flyer is correct about the Lightning bolt...I think someone owes an apology

 

The ILS glide slope is intended to be intercepted at the published glide slope intercept altitude. This point marks the PFAF and is depicted by the “lightning bolt” symbol on U.S. Government charts.

I don't owe anyone an apology

 

He apparently was discussing the altitude where you descend. The FAF is the Maltese cross. And also where you descend.

[sd_flyer 6,023]

That is strange, you have many aircraft on a star coming into an airport like Atlanta, and some pilot can say he doesn't like that particular star and demands another one instead????   

 

If your aircraft is not capable or adequately equipped than yes you can decline STAR/SID or indicate on your IFR flight plan prior the flight "no sid/star". I'm not talking about part 121 or part 135. They have their own set of rules and equipment requirements for type of operation.

 

I've been in and out international airports (part 91) and have never been assigned any  SID or STAR.

 

P.S. You can also enter class Bravo without working mode C transponder just  have to let ATC know in advance. 

[ryanbatc 12,770]

Shite - I am mistaken - not sure of this changed but the cross is only on non precision approaches. Lightning is for precision

 

Sorry!

[fppilot 4,335]

Here is a great table (link below) that may help some members participating in this thread.  In the USA the standard has been a 3° angle of descent from approximately 2,000 ft above ground level (AGL) and a final approach fix (FAF) located approximately 5 nm distant from the touchdown (TDZ) point.  These do often vary based on topography and other local issues such as ground based structures or noise abatement that may restrict the location of the FAF or the published approach altitude at the FAF.  If the FAF is closer to the airport than that, the approach altitude at the FAF will likely be lower, or the descent angle higher. The opposite would be true if the FAF is more distant for some reason.  

 

The rate of descent is based not only on the distance and published angle of descent, but is highly dependent on the approach speed.  As I believe most are aware, the approach speed varies considerably from one aircraft type and model to another.

 

To keep this chart from confusing anyone. please note that the first line under "GROUND SPEED (knots)" contains ground speeds from 30 knots (glider or blimp?) up to 180 knots (fighter jet?). Starting with the 2.0°  line, the remainder of the table expresses the rate of descent in feet per minute (FPM) that correlates to that angle of descent and ground speed.  An airliner approaching at 135 knots at a published 3.0° angle of descent will have a higher rate of descent (715 FPM) than a Beech Baron approaching at 105 knots (555 FPM). For our purposes the table could be distilled down to the lines and columns for 2.0° to  4.0° angles, and air speeds from 60 kts to 150 kts.

 

The almost now outdated paperback bound volumes of Instrument Approach Procedures (IAP) contained tables like this.  Now that it is easy to access digital approach plates on a one-by-one basis, key IAP elements like this get missed.

 

http://www.flightsimbooks.com/foi/app_b_2.php

[Slayer 190]

If your aircraft is not capable or adequately equipped than yes you can decline STAR/SID or indicate on your IFR flight plan prior the flight "no sid/star". I'm not talking about part 121 or part 135. They have their own set of rules and equipment requirements for type of operation.

 

I've been in and out international airports (part 91) and have never been assigned any  SID or STAR.

 

P.S. You can also enter class Bravo without working mode C transponder just  have to let ATC know in advance. 

 

I'm assuming that you have real world experience and that is great info.

 

My only point was that you may request SID or STAR but ATC may not necessarily grant what you want due to changing conditions at the airport. In that respect if say, the runway had changed then the SID or STAR you wanted may no longer be available and they will give an appropriate one. Obviously if you hadn't requested a SID or STAR, ATC will not try to force one on you. If you were not properly equipped for it you would instead receive vectors.

[sd_flyer 6,023]

I'm assuming that you have real world experience and that is great info.

 

My only point was that you may request SID or STAR but ATC may not necessarily grant what you want due to changing conditions at the airport. In that respect if say, the runway had changed then the SID or STAR you wanted may no longer be available and they will give an appropriate one. Obviously if you hadn't requested a SID or STAR, ATC will not try to force one on you. If you were not properly equipped for it you would instead receive vectors.

Yes that is correct. SID /STARs are seldom assigned for small aircraft.

 

Currently I own 172P equipped with GNS430W. I can do some precision GPS approaches, but generally speaking ATC wouldn't like me to plug up the traffic and ask for best vector speed; therefore, most of the time they do prefer to vector me around Yes I'm spoiled

I used to own 182 it was tiny bit faster, more comfortable, and had better useful load. In this aircraft I used to shoot approaches at 100-120 mph which made ATC very happy. Unfortunately 172 is less stable platform in this respect, slower, but more useful for flight instructing purposes.

[sd_flyer 6,023]

Shite - I am mistaken - not sure of this changed but the cross is only on non precision approaches. Lightning is for precision

 

Sorry!

 

There is nothing to be sorry about. Nobody knows everything.

 

Technically speaking ILS doesn't have FAF; however, most of the time when you cleared for approach you have to establish on localizer first before GS intercept. GS could be out of service and you may be the first pilot to find out. In this case you will have to continue on localizer to FAF, and from FAF count your time (if there is time for approach) to MAP (missed approach point). and finally go misssed

 

The bottom line, you do consider FAF even that approach is not non-precision. I also set ILS/LOC on NAV 2 (if available). Good habit if things go sour with NAV1

[wolke85 150]

A very interesting and informative thread so far.

Thank You all very much for all that great info.

However, one question somehow remains to be properly answered - maybe i overread the answer and if so, then i fully apologize in advance, but:

When following the chart as shown in post #5, the "correct" altitude would indeed be 2000' feet as pointed out in #5 as well, but also in #6 - i also assume that 2000' is correct when reading the chart - is this alright?

[WarpD 824]

Technically speaking ILS doesn't have FAF

I just did a scan of the raw ARINC 424 data that I have access to and found that all ILS approaches have a defined Final Approach Fix.