If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
|
#1
|
|||
|
|||
Intercepting the ILS
Hello,
Yesterday I was out getting an IPC. We were doing the Stockton, CA ILS. ATC had us intercepting the localizer at 2000 feet. The altitude for glideslope interception is 1800 ( underlined ). My old CFII taught me that the glideslope interception altitude on the chart is a minimum altitude, and that it was fine to intercept it higher. So I just tootled along at 2000 - figuring it was simpler to do one configuration change at GS interception rather than three changes - one to descend the 200 feet, another to level off, and a third to intercept the glideslope. The new CFII criticized this procedure and told me that the plate specified 1800, and it was wrong to intercept at 2000. Which one was right? - Jerry Kaidor ( ) |
#3
|
|||
|
|||
Intercepting the ILS
|
#4
|
|||
|
|||
Intercepting the ILS
Roy Smith wrote:
wrote: Yesterday I was out getting an IPC. We were doing the Stockton, CA ILS. ATC had us intercepting the localizer at 2000 feet. The altitude for glideslope interception is 1800 ( underlined ). [...] The new CFII criticized this procedure and told me that the plate specified 1800, and it was wrong to intercept at 2000. I can't see any reason not to intercept at 2000. I think your new guy is full of it. As a matter of regulation, the G/S is to be used as primary vertical guidance only from the PFAF inbound. There are some places, where early use of the G/S has resulted in airspace violations, LAX being the most notable. In the case cited, the CFI is nitpicking but is nonetheless legally correct. |
#5
|
|||
|
|||
Intercepting the ILS
wrote: Roy Smith wrote: wrote: Yesterday I was out getting an IPC. We were doing the Stockton, CA ILS. ATC had us intercepting the localizer at 2000 feet. The altitude for glideslope interception is 1800 ( underlined ). [...] The new CFII criticized this procedure and told me that the plate specified 1800, and it was wrong to intercept at 2000. I can't see any reason not to intercept at 2000. I think your new guy is full of it. As a matter of regulation, the G/S is to be used as primary vertical guidance only from the PFAF inbound. There are some places, where early use of the G/S has resulted in airspace violations, LAX being the most notable. Let's be argumentative here. What regulation are you referring to? In the case of LAX (the Civet 4 arrival I quoted earlier), the problem was that following the glideslope caused the airplane to violate published crossing restrictions. In the case cited, the CFI is nitpicking but is nonetheless legally correct. At SCK there was no crossing restriction either given in the clearance or published. The pilot is free to descend *at his discretion* from 2000 to 1800. Following the glideslope is a perfectly acceptable way of doing that. The CFI is not only nit-picking, but in this instance is wrong. Not only that, but he's making additional unnecessary work. |
#6
|
|||
|
|||
Intercepting the ILS
wrote:
wrote: Roy Smith wrote: Let's be argumentative here. What regulation are you referring to? In the case of LAX (the Civet 4 arrival I quoted earlier), the problem was that following the glideslope caused the airplane to violate published crossing restrictions. In the Los Angeles case the violations occurred inside the CIVET arrival, actually on the ILS profile. Those fixes are issued under Part 97 just as it the legal point at which the G/S *controls* for descent(the PFAF). In the case cited, the CFI is nitpicking but is nonetheless legally correct. At SCK there was no crossing restriction either given in the clearance or published. The pilot is free to descend *at his discretion* from 2000 to 1800. Following the glideslope is a perfectly acceptable way of doing that. The CFI is not only nit-picking, but in this instance is wrong. Not only that, but he's making additional unnecessary work. I agree that the CFI is procedurally wrong, although legally correct. Let me put it another way: the CFI is stuck on one aspect of the issue, the other being that the pilot can make certain elections so long as he does not use the G/S as primary for descent prior to the PFAF. The CFI has a duty to teach resonable procedure while pointing out the legal nuances of when the G/S is primary for altitude control. It sounds like he covered only one aspect of the issue, which while correct legally, is incorrect and out of context procedurally. |
#7
|
|||
|
|||
Intercepting the ILS
|
#8
|
|||
|
|||
Intercepting the ILS
|
#9
|
|||
|
|||
Intercepting the ILS
JPH wrote:
Can you give an example of how an airspace violation could occur? It seems that as long as the pilot doesn't descend below the minimum altitude published for the segment of the approach he's in, then descending on the glidepath can't put the aircraft any lower than dropping down immediately to the minimum segment altitude at the beginning of the segment. If he's in the Intermediate, then the glidepath will more than likely keep him higher than dropping down to the minimum altitude due to the length of the intermediate normally compensating for the required altitude loss at 150 ft per mile optimum. If the airspace violation would be from the aircraft being too high, then perhaps the procedure should have a maximum altitude shown or the controller issue a crossing restriction. It's happen at LAX quite a few times when the air is hot and the underlying Ontario airspace rises to provide less than 1,000 feet of vertical on the LAX G/Ses. The G/S doesn't move. The glideslope intercept altitude is a minimum altitude, not a mandatory or maximum altitude. From a TERPS standpoint there's no problem with descending on the glideslope from 2000 on the procedure in question instead of 1800. True enough, and if the pilot wants to remain above the G/S that is perfectly legal. But, any charted minimum stepdown altitudes prior to the PFAF are governing, not the G/S. If the pilot uses the glideslope for backup vertical guidance to give a smooth transition to the final segment (while using the altimeter readout outside the FAF to ensure he doesn't descend below 1800) then what's wrong with that? Nothing wrong with that. |
#10
|
|||
|
|||
Intercepting the ILS
If the pilot uses the glideslope for backup vertical guidance to give a
smooth transition to the final segment (while using the altimeter readout outside the FAF to ensure he doesn't descend below 1800) then what's wrong with that? Nothing wrong with that. That isn't really correct either. There's no necessity to monitor the altimeter at SCK because there's no step-down fixes or other crossing restrictions at issue. Above 1800 feet on the glideslope, the glideslope is advisory, but the pilot is perforce satisfying the =1800 foot minimum altitude requirement. Below 1800 feet the glideslope becomes primary. So in practical terms nothing happens at 1800 feet. There's nothing to monitor. (OK. I know, you part 121 types have now reached a point where the weather can below minimums without necessitating a miss.) At *Stockton* (the subject of the question), there is no legal issue. At LAX on the Civet arrival, and other situations where there are step-down altitudes on the localizer outside the PFAF, there is a potential issue. The step down minima take precedence over the GS altitude. |
Thread Tools | |
Display Modes | |
|
|