Approach Clearance vs Platform Altitude
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Approach Clearance vs Platform Altitude
Hello!
Question: You are flying towards an ILS approach with a published initial platform altitude of 2500 feet. You are presently at 4000 feet and, say, 14 miles out when ATC give you an intercept heading and clear you for the approach. Is it expected that you will descend to 2500 feet as published or maintain 4000 feet until on the glideslope? Or, do you have a choice??
Would the answer change if you are significantly off the extended centreline when giving the intercept heading?
Many thanks for any replies!!
CP
Question: You are flying towards an ILS approach with a published initial platform altitude of 2500 feet. You are presently at 4000 feet and, say, 14 miles out when ATC give you an intercept heading and clear you for the approach. Is it expected that you will descend to 2500 feet as published or maintain 4000 feet until on the glideslope? Or, do you have a choice??
Would the answer change if you are significantly off the extended centreline when giving the intercept heading?
Many thanks for any replies!!
CP
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Originally Posted by captainpaddy
Hello!
Question: You are flying towards an ILS approach with a published initial platform altitude of 2500 feet. You are presently at 4000 feet and, say, 14 miles out when ATC give you an intercept heading and clear you for the approach. Is it expected that you will descend to 2500 feet as published or maintain 4000 feet until on the glideslope? Or, do you have a choice??
Would the answer change if you are significantly off the extended centreline when giving the intercept heading?
Many thanks for any replies!!
CP
Question: You are flying towards an ILS approach with a published initial platform altitude of 2500 feet. You are presently at 4000 feet and, say, 14 miles out when ATC give you an intercept heading and clear you for the approach. Is it expected that you will descend to 2500 feet as published or maintain 4000 feet until on the glideslope? Or, do you have a choice??
Would the answer change if you are significantly off the extended centreline when giving the intercept heading?
Many thanks for any replies!!
CP
MD11s all over the world and this is the procedure we follow........
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Interesting Question, you get two problems around Europe one in the UK where you are cleared on the LLZ and then can't get a word in anywhere to call established, and either miss the GS or start the descent and hope. In the rest of Europe you are cleared for the ILS approach and they turn you in so close that the GS comes in before the LLZ and I get the distinct impression that after calling for further descent that they were expecting you to descnd to the platform altitude anyway, or they tell you to descend with the GS .
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Thanks for the replies guys!
I have understood that in the UK they tend not issue a full approach clearance and say "descend on the ILS" or whatever in order to ensure that you maintain your current altitude until glideslope intercept.
I have always operated to fogrunners philosophy both in the US and IRL/UK and had no problems, however have recently had a problem in Espana similar to what Best Foot Forward has said. In this case we were a good few miles right of the centreline and previously cleared to a flight level. We were then given an intercept heading and cleared for the approach. No further descent indicated, no QNH given. Shortly afterwards, we were asked by an upset ATCO whether we were descending to the initial patform altitude or not! I have difficulty understanding how we were to guess the QNH and descend to an altitude while still not established on any approach segment?
It would make sense to me that you should at least be established on a published segment of the approach before commencing descent. Does anyone know where I might find written guidance to this problem? I certainly can't find anything anywhere!!
CP
I have understood that in the UK they tend not issue a full approach clearance and say "descend on the ILS" or whatever in order to ensure that you maintain your current altitude until glideslope intercept.
I have always operated to fogrunners philosophy both in the US and IRL/UK and had no problems, however have recently had a problem in Espana similar to what Best Foot Forward has said. In this case we were a good few miles right of the centreline and previously cleared to a flight level. We were then given an intercept heading and cleared for the approach. No further descent indicated, no QNH given. Shortly afterwards, we were asked by an upset ATCO whether we were descending to the initial patform altitude or not! I have difficulty understanding how we were to guess the QNH and descend to an altitude while still not established on any approach segment?
It would make sense to me that you should at least be established on a published segment of the approach before commencing descent. Does anyone know where I might find written guidance to this problem? I certainly can't find anything anywhere!!
CP
Last edited by captainpaddy; 6th Apr 2006 at 10:08.
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In my experience around Europe, you'll either be cleared to "descend with the glideslope" on calling Localiser established or "cleared for ILS" prior to calling "established"...either way, assuming it means you can intercept from below, maintain the last cleared altitude.
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Yes had a similar situation at a field we normally operate into to, caught me by surprise being cleared for the ILS so far away, due to high terrain in the area we chose to descend to MSA until reaching a published segment.
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You stay at your cleared level until you have the G/S guidance to continue descent. Incidentaly, in the UK after localiser capture, don't worry if you can't get a word in on the R/T; descend on the glideslope as that is what ATC are expecting you to do............
PP
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I talked to a (real-life) German ATCO about this question. He told me that when they clear you for the ILS-Approach they want you to descend as published. To reduce the confusion they usually add "...descent altitude XXXX feet to establish". But usually they bring you down to the published altitude before clearing for the ILS-Approach.
Sorry, a little off-topic:
When we were talking about this some questions came up. How will you manage this in the cockpit? For example the A320: When cleared for the ILS you usually "press the APPR-Button". This makes the FMS capture the LOC and GS. In our scenario (descending to the published altitude before GS capture) it means that the FMS will stay at present altitude till GS-intercept. Does the FMS react on any new altitude-input? Or do you have to only capture the LOC, descent to the published altitude to then also capture the GS? Which means a higher workload. What about other aircraft?
Robert
Sorry, a little off-topic:
When we were talking about this some questions came up. How will you manage this in the cockpit? For example the A320: When cleared for the ILS you usually "press the APPR-Button". This makes the FMS capture the LOC and GS. In our scenario (descending to the published altitude before GS capture) it means that the FMS will stay at present altitude till GS-intercept. Does the FMS react on any new altitude-input? Or do you have to only capture the LOC, descent to the published altitude to then also capture the GS? Which means a higher workload. What about other aircraft?
Robert
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Once cleared for the approach the correct procedure will be to dial in the published glideslope intercept alt and prepare the a/c for the APP. ie. Arm APP ect. You should begin a decent to the APP alt, time (distance) permitting.
Should you intercept the glideslope on the way down, no hassle. You can also manage that decent using a reduced verticle speed decent should you want to achieve a earlier glislope interception. The long and the short of it is that you will normally be below the glideslope when cleared for APP and ATC is aware of the verticle profile to follow.
Should you intercept the glideslope on the way down, no hassle. You can also manage that decent using a reduced verticle speed decent should you want to achieve a earlier glislope interception. The long and the short of it is that you will normally be below the glideslope when cleared for APP and ATC is aware of the verticle profile to follow.
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Flight Simmer,
Arming the LOC will prepare the aircraft to intercept the LOC only, pushing the ARM PB will arm the LOC and GS capture. Prior to intercepting the GS you can continue to cleared altitude or manipulate your ROD in Managed DES or V/S as mentioned by divinhover.
Arming the LOC will prepare the aircraft to intercept the LOC only, pushing the ARM PB will arm the LOC and GS capture. Prior to intercepting the GS you can continue to cleared altitude or manipulate your ROD in Managed DES or V/S as mentioned by divinhover.
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Approach Clearance vs. Platform Altitude
To answer the question accurately, you have to look at the specific approach plate. Generally (almost always) the glide slope intercept altitude displayed is the minimum. So, you can intercept farther out from the runway at a higher altitude...that's ok.
But, in very few cases the published glide slope intercept altitude is shown as "Mandatory". In this case, one would be obliged to maintain the last assigned altitude until established on a published segment of the approach...THEN, descend to the mandatory glide slope intercept altitude for the actual glide slope intercept.
In either case...it's important to remember that descent from the last assigned altitude cannot commence prior to becoming established on a published segment of the approach.
What constitutes 'established'? With regard to the localizer, you are considered established when the needle is alive. In some cases, you will be flying an intermediate segment prior to localizer intercept. Again, if the needle is alive, you're good enough to be considered established. You can then begin descent to the minimum altitude for that segment (assuming clearance to do so).
With regard to the Airbus, you have to make the aircraft do what you want it to do...not what is programed by the engineers. However, keep in mind when the winds at your altitude are in excess of a ten knot tailwind, the decelerated approach technique is not allowed. (FCOM 3.03.18 P1). In this case, you must intercept the glide path as per the Airbus profile (or your airline's SOP).
I hope this helps....
But, in very few cases the published glide slope intercept altitude is shown as "Mandatory". In this case, one would be obliged to maintain the last assigned altitude until established on a published segment of the approach...THEN, descend to the mandatory glide slope intercept altitude for the actual glide slope intercept.
In either case...it's important to remember that descent from the last assigned altitude cannot commence prior to becoming established on a published segment of the approach.
What constitutes 'established'? With regard to the localizer, you are considered established when the needle is alive. In some cases, you will be flying an intermediate segment prior to localizer intercept. Again, if the needle is alive, you're good enough to be considered established. You can then begin descent to the minimum altitude for that segment (assuming clearance to do so).
With regard to the Airbus, you have to make the aircraft do what you want it to do...not what is programed by the engineers. However, keep in mind when the winds at your altitude are in excess of a ten knot tailwind, the decelerated approach technique is not allowed. (FCOM 3.03.18 P1). In this case, you must intercept the glide path as per the Airbus profile (or your airline's SOP).
I hope this helps....
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There seems to be some conflicting info being offered here. On re-reading I can see where some of this at least has come from.
When in the UK and being radar vectored for an ILS approach, which on the ILS approach chart has a procedural ILS depicted, you do not have to descend to the published platform once cleared to descend on the glideslope. Even if you were flying the procedural ILS, unless it depicts a platform altitude that you have to be 'at', you can fly a constant descent to only actually pass this altitude as you capture the glideslope.
However, and this is something we regularly experience in places like Spain, you will often fly an approach procedure from the Initial Approach Fix (Alicante springs to mind), when you are descending to a flight level, under radar, and then they clear you for the approach. This is the last they say to you until they hand you over to the Tower frq. In this scenario you descend in accordance with the procedure without further prompting, obeying the various altitude restrictions depicted on the chart until you are fully established on the ILS.
I believe that the UK system of controllers asking you to report established on the localiser before being cleared to descend with the glideslope came from places like Heathrow where controllers would clear a/c from a long way out for the ILS and some pilots were then interpreting this to mean they could descend to the platform altitude depicted on their charts. This led to many a/c descending to the platform (something like 3000'?) at considerable distances out (like 20nm) and then overflying London!
I personally do not see how you can descend to the platform unless you are either;
a. On the published procedure. or
b. Under radar control with a radar minimums chart available to you.
Otherwise you need to stay at your (radar vectored) cleared altitude or MSA until you establish on the localiser (which incidently is at half scale deflection, not "needle alive") and then capture the glideslope.
PP
When in the UK and being radar vectored for an ILS approach, which on the ILS approach chart has a procedural ILS depicted, you do not have to descend to the published platform once cleared to descend on the glideslope. Even if you were flying the procedural ILS, unless it depicts a platform altitude that you have to be 'at', you can fly a constant descent to only actually pass this altitude as you capture the glideslope.
However, and this is something we regularly experience in places like Spain, you will often fly an approach procedure from the Initial Approach Fix (Alicante springs to mind), when you are descending to a flight level, under radar, and then they clear you for the approach. This is the last they say to you until they hand you over to the Tower frq. In this scenario you descend in accordance with the procedure without further prompting, obeying the various altitude restrictions depicted on the chart until you are fully established on the ILS.
I believe that the UK system of controllers asking you to report established on the localiser before being cleared to descend with the glideslope came from places like Heathrow where controllers would clear a/c from a long way out for the ILS and some pilots were then interpreting this to mean they could descend to the platform altitude depicted on their charts. This led to many a/c descending to the platform (something like 3000'?) at considerable distances out (like 20nm) and then overflying London!
I personally do not see how you can descend to the platform unless you are either;
a. On the published procedure. or
b. Under radar control with a radar minimums chart available to you.
Otherwise you need to stay at your (radar vectored) cleared altitude or MSA until you establish on the localiser (which incidently is at half scale deflection, not "needle alive") and then capture the glideslope.
PP
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Originally Posted by Pilot Pete
I personally do not see how you can descend to the platform unless you are either;
a. On the published procedure. or
b. Under radar control with a radar minimums chart available to you.
PP
a. On the published procedure. or
b. Under radar control with a radar minimums chart available to you.
PP
1. maintain last asigned altitude untilon a published approach segment, then descend or,
2. descend immediately to the minimum radar vectoring altitude and then once established on the approach, descend to the published minimum altitude
To me, this still poses the problem of what ATC expect you to do? Does having a Radar Vectoring Chart with you entitle you to descend while still off-route if an approach clearance has been received?
If you don't have the Radar Vectoring Chart do you have to maintain the last assigned level? In that case, what if the chart exists but you don't have it? I know that sounds silly, but it means we now need two charts to fly the procedure in the manner ATC are expecting. It's all very vague!!!! HELP!!!
The longer this discussion goes on the more it seems that there isn't actually an agreed procedure or at least we are not all operating in the same way.
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Sorry, yeah it's in the reading of what I wrote.
You can only descend to the radar minimum altitude if the controller has given you a clearance to do so. "cleared for the ILS" is not a clearance to descend to radar minimums. Remember that under radar control the controller is responsible for terrain separation, but that doesn't absovle the good pilot from ensuring he is still terrain safe. This threw up questions for me several years ago when I started flying commercially. I asked the line trainers how I could justify descending below MSA whilst under radar control with no radar vectoring chart available to me. They couldn't come up with anything other than "you just have to trust them", which never really satisfied me.....anyhow off topic there.
Basically, if they give you a final vector to intercept the localiser, stay at the cleared altitude.
If you are flying a procedure, descend in accordance with the procedure once you have been cleared for the procedure. This applies even if you are under radar coverage. I refer to Alicante once again as a good example of this. Take a look at the approach and ILS-Zulu 10 plate for Alicante which shows it quite well. As you fly towards VILNA the minimum FL is FL80 (from the approach chart), with a minimum holding level of FL70 at VILNA. The controllers have you under radar, clear you down to FL70 (minimum radar vectoring altitude in the sector is 6000').
As you approach VILNA you are cleared for the ILS ZULU for runway 10. That is all they say. It is now up to the pilot to fly the procedure, even though you are being monitored on radar. We need to stay above FL70 going over VILNA and then descend in accordance with the procedure. From VILNA you fly a 20dme arc which has a minimum altitude of 5900', so we cross VILNA and start to descend to 5900', remembering to set the QNH!. You fly the arc to intercept the localiser and once established you follow the descend restrictions on the chart to ensure you step down over the mountains! 17.6d on the ILS descend from 5900' to 4200'. 14.6d descned to 3300'. At 9.8d you intercept the glideslope and descend to minimums.
Note that the protected area for a glideslope signal extends to 10nm, so at Alicante you are only just inside that when you intercept the glide at the lowest platform depicted on the chart. Indeed Alicante has NOTAMs about the protected areas for localiser and glideslope, reminding pilots of the maximum range where no interference has been checked. Often on pretty much straight in approaches (not Alicante) you are given a final vector and cleared for the approach. If you are outside 25nm the localiser signal is not guaranteed and if you arm the localiser and capture it the a/c will wander from left to right following this distorted signal. The best way to do it is to just fly along the localiser in HDG SEL until you are within the defined range and the signal appears stable.
So going back to Alicante runway 10, the controllers expect you to fly the procedure once cleared for it and to descend in accordance with it. You can stay above the minimum altitudes if you want, but must not go below them.
Can you see how this differs from say radar vectors? Here (in the UK) the controllers "radar control" you, giving you headings to steer and descent to altitudes to keep you terrain safe. They put you on an intercept heading and tell you to "report established" on the localiser. If they then clear you for descent on the glideslope you stay at the cleared altitude and intercept the glideslope before further descent. Why? Well if they vector you quite a way out, say 20nm and put you on an intercept on what basis are you taking it upon yourself to descned to a platform drawn on a chart which applies to a procedural approach? You may well be no where near the procedure at 20nm out, especially if it is designed to take you from a beacon on the airfield, outbound and then turn back inbound to establish on the ILS. What if the MSA is above the platform? You have to justify descending below MSA every time you do an approach, be it because you are visual, under radar control or on a procedure above procedure minima, or established on a let down aid such as ILS. So if a radar controller had you at his radar minima (below MSA), yet some distance out, you can't justify descending to a platform for a procedure that you are not on because he has told you that you are clear for the ILS. I would always stay at the cleared altitude until I had the justification to descend further safely.
I hope this helps.
PP
You can only descend to the radar minimum altitude if the controller has given you a clearance to do so. "cleared for the ILS" is not a clearance to descend to radar minimums. Remember that under radar control the controller is responsible for terrain separation, but that doesn't absovle the good pilot from ensuring he is still terrain safe. This threw up questions for me several years ago when I started flying commercially. I asked the line trainers how I could justify descending below MSA whilst under radar control with no radar vectoring chart available to me. They couldn't come up with anything other than "you just have to trust them", which never really satisfied me.....anyhow off topic there.
Basically, if they give you a final vector to intercept the localiser, stay at the cleared altitude.
If you are flying a procedure, descend in accordance with the procedure once you have been cleared for the procedure. This applies even if you are under radar coverage. I refer to Alicante once again as a good example of this. Take a look at the approach and ILS-Zulu 10 plate for Alicante which shows it quite well. As you fly towards VILNA the minimum FL is FL80 (from the approach chart), with a minimum holding level of FL70 at VILNA. The controllers have you under radar, clear you down to FL70 (minimum radar vectoring altitude in the sector is 6000').
As you approach VILNA you are cleared for the ILS ZULU for runway 10. That is all they say. It is now up to the pilot to fly the procedure, even though you are being monitored on radar. We need to stay above FL70 going over VILNA and then descend in accordance with the procedure. From VILNA you fly a 20dme arc which has a minimum altitude of 5900', so we cross VILNA and start to descend to 5900', remembering to set the QNH!. You fly the arc to intercept the localiser and once established you follow the descend restrictions on the chart to ensure you step down over the mountains! 17.6d on the ILS descend from 5900' to 4200'. 14.6d descned to 3300'. At 9.8d you intercept the glideslope and descend to minimums.
Note that the protected area for a glideslope signal extends to 10nm, so at Alicante you are only just inside that when you intercept the glide at the lowest platform depicted on the chart. Indeed Alicante has NOTAMs about the protected areas for localiser and glideslope, reminding pilots of the maximum range where no interference has been checked. Often on pretty much straight in approaches (not Alicante) you are given a final vector and cleared for the approach. If you are outside 25nm the localiser signal is not guaranteed and if you arm the localiser and capture it the a/c will wander from left to right following this distorted signal. The best way to do it is to just fly along the localiser in HDG SEL until you are within the defined range and the signal appears stable.
So going back to Alicante runway 10, the controllers expect you to fly the procedure once cleared for it and to descend in accordance with it. You can stay above the minimum altitudes if you want, but must not go below them.
Can you see how this differs from say radar vectors? Here (in the UK) the controllers "radar control" you, giving you headings to steer and descent to altitudes to keep you terrain safe. They put you on an intercept heading and tell you to "report established" on the localiser. If they then clear you for descent on the glideslope you stay at the cleared altitude and intercept the glideslope before further descent. Why? Well if they vector you quite a way out, say 20nm and put you on an intercept on what basis are you taking it upon yourself to descned to a platform drawn on a chart which applies to a procedural approach? You may well be no where near the procedure at 20nm out, especially if it is designed to take you from a beacon on the airfield, outbound and then turn back inbound to establish on the ILS. What if the MSA is above the platform? You have to justify descending below MSA every time you do an approach, be it because you are visual, under radar control or on a procedure above procedure minima, or established on a let down aid such as ILS. So if a radar controller had you at his radar minima (below MSA), yet some distance out, you can't justify descending to a platform for a procedure that you are not on because he has told you that you are clear for the ILS. I would always stay at the cleared altitude until I had the justification to descend further safely.
I hope this helps.
PP
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So, let's say you're at 6500', LOC established, cleared approach by ATC. Published final approach alt. is 3500'.
Are you 'legal' if you intercept the G/S from 6500' or would ATC need to tell you to 1) "descent on the glide" or 2) clear you to the published final app. alt.?
Beats me...
S.
Are you 'legal' if you intercept the G/S from 6500' or would ATC need to tell you to 1) "descent on the glide" or 2) clear you to the published final app. alt.?
Beats me...
S.
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Pilot Pete,
Thanks a mill! I'm back on track again I think!
Sjakie, as I understand it, published altitudes on an approach are minimum altitudes (unless mandatory is specifically indicated). Therefore, you are not obliged to be at the specified altitude at a particular point and can quite legitamitely remain above any altitudes on the chart. Intercepting from 6500' would be legitimate from a CDA point of view, even though the chart may show glideslope intercept at 9D for example. However, glideslope coverage is not guaranteed at the sort of range you would need to be at when intercepting from 6500', so while it's not necessarily illegal, you should really be descending to the published altitude and then intercept from there.
However, I may just be completely wrong!!!!
Thanks a mill! I'm back on track again I think!
Sjakie, as I understand it, published altitudes on an approach are minimum altitudes (unless mandatory is specifically indicated). Therefore, you are not obliged to be at the specified altitude at a particular point and can quite legitamitely remain above any altitudes on the chart. Intercepting from 6500' would be legitimate from a CDA point of view, even though the chart may show glideslope intercept at 9D for example. However, glideslope coverage is not guaranteed at the sort of range you would need to be at when intercepting from 6500', so while it's not necessarily illegal, you should really be descending to the published altitude and then intercept from there.
However, I may just be completely wrong!!!!
