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#31
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Intercepting the ILS
wrote in message
oups.com... 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? Assuming that by intercepting at 2,000 feet you're not infringing any other published rules (e.g. airspace or specific instructions on the approach plate) I would suggest you look at the published range for the ILS signal. So long as you're within the published range of the glideslope signal when doing a 2000' intercept, I can't see you're doing anything wrong - particularly as you were presumably doing as you'd been told by an authoritative controller. After all, it's common to fly the first bit of an approach according to the book and then to take different instructions from the controller. D. |
#32
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Intercepting the ILS
David Cartwright wrote:
Assuming that by intercepting at 2,000 feet you're not infringing any other published rules (e.g. airspace or specific instructions on the approach plate) I would suggest you look at the published range for the ILS signal. So long as you're within the published range of the glideslope signal when doing a 2000' intercept, I can't see you're doing anything wrong - particularly as you were presumably doing as you'd been told by an authoritative controller. After all, it's common to fly the first bit of an approach according to the book and then to take different instructions from the controller. The published range of a G/S has little practical meaning to a pilot. Unlike service volumes for VORs it has no flight plan or route limitation aspect. If you can receive the G/S prior to the PFAF, its only advisory in any case, so you are free to use it as you choose, provided you don't violate any minimum segment altitude or stepdown fixes or any aspect of an ATC clearance. |
#33
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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. |
#34
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Intercepting the ILS
The altitude at the marker is a double check on the
altimeter and the glide slope. If the altimeter is set incorrectly or broken or if you have intercepted the wrong glide slope lobe, the pilot has an opportunity to catch the error and figure out what is wrong. -- James H. Macklin ATP,CFI,A&P -- The people think the Constitution protects their rights; But government sees it as an obstacle to be overcome. some support http://www.usdoj.gov/olc/secondamendment2.htm See http://www.fija.org/ more about your rights and duties. wrote in message oups.com... | 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. | |
#35
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Intercepting the ILS
The altitude at the marker is a double check on the
altimeter and the glide slope. If the altimeter is set incorrectly or broken or if you have intercepted the wrong glide slope lobe, the pilot has an opportunity to catch the error and figure out what is wrong. That is of course true - but it's a different altitude, 1758 in this case. It's the 1800 altiitude that loses significance once the GS has been intercepted. BTW, the chances of following the wrong lobe of the GS to the FAF without noticing a problem is close to nil. It either has reverse sensing or requires ridiculous rates of descent. |
#36
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Intercepting the ILS
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#37
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Intercepting the ILS
We are procedurally in violent agreement. Nonetheless, the G/S is not
primary prior to the PFAF, any minimum altitude constraints notwithstanding. That is the legalese of Part 97. I am just the messenger. We're agreed that at SCK following the glide slope down from the 2000 foot vector altitude is the best procedure. We're also agreed that the G/S is not primary outside the PFAF. Instead, one must abide by the published altitudes - in this case we must remain above 1800 until this PFAF. At SCK, this is logically guaranteed by our "best procedure". However, I detect that your position is still that some sufficiently zealous FAA inspector could violate me for using the G/S to descend to 1800. (otherwise how could the new instructor be "technically correct"?). I disagree. If that is your position, please cite which verse of Part 97 that this zealous inspector could attempt to violate me on? Which regulation does our agreed best procedure not comply with? It's pointless discussing legality without reference to the law. |
#38
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Intercepting the ILS
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#39
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Intercepting the ILS
Garner Miller wrote:
It's *vitally* important to check the glideslope crossing altitude at marker, of course, to ensure that you're not on a false glideslope. The first false G/S above the normal G/S is typically 1500 higher at the P-FAF. Only in extreme situations is it possible to intercept the false G/S. And, of course, if you did, it would cause twice the descent rate you expected once stablized on final approach. |
#40
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Intercepting the ILS
I agree with everything you just wrote. But, you have not addressed
my question. In what way does/can following the glideslope from 2000 to 1800 feet at SCK violate the regulatory implications of the SCK ILS's 8260-3? There is no rule that says "thou shalt not follow the G/S unless it is primary". What the rules say is "thou shall not bust the published altitude restrictions prior to the PFAF". Since it isn't logically possible to violate the altitude restrictions *in this instance* by following the G/S, it can't be illegal to do so. The regulatory basis is 91.175(a) which requires "Unless otherwise authorized by the Administrator, when an instrument letdown to a civil airport is necessary, each person operating an aircraft, except a military aircraft of the United States, shall use a standard instrument approach procedure prescribed for the airport in part 97 of this chapter." Part 97 does not prescribe pilot technique. It prescribes the tracks and altitudes to be flown. If those are complied with, there's no possible violation. |
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