Hello ATC types! My question for you fine people is why we are assigned a lower altitude to intercept the glide slope when our current altitude will do just fine?

Example: when already below the slope at 4000 and "Jazz 845 turn heading 090 to intercept descend 3000 cleared the ILS 05" OR when we're already on the LOC and "descend to 3000 cleared the ILS 05". Couldn't we just stay at 4000 and descend on the slope?

Thanks.

I am a pilot type but I think it has something to do with spacing. If someone is on an intercept heading and misses the loc but you're spaced apart by 1000 feet it gives them a n out.

Example: when already below the slope at 4000 and "Jazz 845 turn heading 090 to intercept descend 3000 cleared the ILS 05" OR when we're already on the LOC and "descend to 3000 cleared the ILS 05". Couldn't we just stay at 4000 and descend on the slope?

It is usually to do with who is joining alongside you on the parallel. If it is IFR we can't join aircraft side by side at the same altitude on the parallel approaches. We run a "high/low" operation which can be switched around, so when on 05 being asked to descend to 3000ft before the 4000ft GS point...the chances are that there is an aircraft on 06L that has to join at that point and is already higher than you are/were.

Super cool thanks!

I don't work YYZ but I do work TCU. Other than what has already been stated I would say we do this also when there is a huge tailwind in order to put you in the same winds as the guy you are following so that the catch up rate is reduced.

Married a Canadian wrote:

Example: when already below the slope at 4000 and "Jazz 845 turn heading 090 to intercept descend 3000 cleared the ILS 05" OR when we're already on the LOC and "descend to 3000 cleared the ILS 05". Couldn't we just stay at 4000 and descend on the slope?

It is usually to do with who is joining alongside you on the parallel. If it is IFR we can't join aircraft side by side at the same altitude on the parallel approaches. We run a "high/low" operation which can be switched around, so when on 05 being asked to descend to 3000ft before the 4000ft GS point...the chances are that there is an aircraft on 06L that has to join at that point and is already higher than you are/were.

Interesting. How do the triples do it like DFW? Are those rules or just procedure --

How do the triples do it like DFW

I don't know how they do it in the US. Pretty sure they would have some form of IFR separation built into any parallel approach procedure. Altitude is the easiest way to do it.

RE the tailwind part. We sometimes do this in YYZ but less so when we are operating in a dual or triple mode as both runways are affected which means both sides would need to be lower...which can't happen due to the original IFR/glide slope altitude point I made.

Married a Canadian wrote:

How do the triples do it like DFW

I don't know how they do it in the US. Pretty sure they would have some form of IFR separation built into any parallel approach procedure. Altitude is the easiest way to do it.

RE the tailwind part. We sometimes do this in YYZ but less so when we are operating in a dual or triple mode as both runways are affected which means both sides would need to be lower...which can't happen due to the original IFR/glide slope altitude point I made.

I work dual runways as well. Our operation is different though I suspect.

I work dual runways as well. Our operation is different though I suspect

Do you work YUL? The only parallel runway op I can think of to the East??

Married a Canadian wrote:

I work dual runways as well. Our operation is different though I suspect

Do you work YUL? The only parallel runway op I can think of to the East??

Yeah, YUL TCU.

YUL TCU.

Didn't know..thankyou. I will presume though that you do a similar "dual" operation to YYZ...land and depart both runways..5 mile arrival spacing?

We do for certain try to get planes down to the same altitude when there is a tailwind (on the 06s for sure). It is just less common than my original answer in busy arrival times....not enough altitudes to go round and you can't stay within the parallel joining rules in IFR weather.
I do know that pilots are sometimes unaware of what is happening alongside them on the parallel approach especially when the planes are on another frequency and it is IFR. Quite often they will be asked to descend below GS point and dog it down not realising they are blocking an altitude for a joiner on the opposite side. We usually have to tell them to expedite and give the reason why on the frequency.

Married a Canadian wrote:

YUL TCU.

Didn't know..thankyou. I will presume though that you do a similar "dual" operation to YYZ...land and depart both runways..5 mile arrival spacing?

I wish! On 06's we use 3nm on the left, 6nm on the right and tower departs 06R and operational only on 06L. Same thing on 24's except reversed, 24R 3nm 24L 6nm.

We do for certain try to get planes down to the same altitude when there is a tailwind (on the 06s for sure). It is just less common than my original answer in busy arrival times....not enough altitudes to go round and you can't stay within the parallel joining rules in IFR weather.
I do know that pilots are sometimes unaware of what is happening alongside them on the parallel approach especially when the planes are on another frequency and it is IFR. Quite often they will be asked to descend below GS point and dog it down not realising they are blocking an altitude for a joiner on the opposite side. We usually have to tell them to expedite and give the reason why on the frequency.

We only have on controller working both LOC's so once the aircraft has his app clearance we will often ask no delay to 3000' for similar winds.

Married a Canadian wrote:

YUL TCU.

Didn't know..thankyou. I will presume though that you do a similar "dual" operation to YYZ...land and depart both runways..5 mile arrival spacing?

Mac, YUL doesn't do independent parallel ILS approaches, only dependent. So, no LOC monitor position, no NTZ, and as Braun said, only one finals guy doing both LOCs on the same frequency. No real need for independent ILS approaches. Besides, let's face it, one guy running two LOCs is more fun than running one !

As far as I know, only you guys and YVR consistently do independent ILS approaches. YYC, with the new parallel runway, has the procedures and the monitor position in place for it, but no staff, so they dont use it much. They are more or less in the same boat as YUL, in that there is no real need for independent ops, as they only do 248,000 movements/year (slightly more than YUL, which was at 220,000 in 2015.)

Mac, YUL doesn't do independent parallel ILS approaches, only dependent. So, no LOC monitor position, no NTZ, and as Braun said, only one finals guy doing both LOCs on the same frequency. No real need for independent ILS approaches. Besides, let's face it, one guy running two LOCs is more fun than running one !

As far as I know, only you guys and YVR consistently do independent ILS approaches. YYC, with the new parallel runway, has the procedures and the monitor position in place for it, but no staff, so they dont use it much. They are more or less in the same boat as YUL, in that there is no real need for independent ops, as they only do 248,000 movements/year (slightly more than YUL, which was at 220,000 in 2015.)

Thanks for the info. I knew YVR did independent approaches as we have had controllers from YYZ move out West in recent years. Just had a YYC controller join us here so he has explained their operation.
Depending on our traffic level we sometimes have one controller working both localisers in either the dual or triple operation. In the dual in light traffic they will just work from the bedpost all the way onto final approach. In a busy triple operation we split into inner/outer arrival...so outer sequences from the bedposts into the downwind, inner will turn final onto both localisers.
This will usually be the time in relation to the topic of this thread where planes will be put below the glideslope for joining traffic.

Interesting to know the different operations in Canada.

^

Since we are on the subject Mac, there is something I have always wondered about YYZ. When you're running both LOCs with one controller in a dependent ILS config (no monitor), how many miles to do you put diagonally between aircraft on each LOC, assuming IFR conditions and no visuals ? Or do you always operate with the monitor position open, even with only 1 controller working both LOCs ?

The reason I ask is because MANOPS clearly specifies that for dependent ops, the 2 nm diagonal spacing is for runways that are 4300-9000 ft apart. YYZ's 23 and 24R are 10,800 ft apart, so technically, MANOPS doesn't cover YYZ's situation in dependent ops.