Arrival and ILS question

[falcon20driver]

Here's the chart
http://www.fltplan8.com/AppCharts/GIFCHARTS/00320I26_0001.gif

I don't remember ever seeing a mandatory altitude at the FAF on any other ILS chart, looks to me like 2000 is the minimum alt. outside FOSOM, and 2000 is the mandatory alt. inside FOSOM until glideslope intercept or ESCOE for the LOC approach. Going to do some reading and see if that's correct.

Edit: After looking at it again, I don't see why they would have the 2000 minimum altitude at glideslope intercept if 2000 was the manditory altitude, I think the 2000 manditory is only for the LOC approach.

 

[TIS]

This is why I HATE Gub'ment charts!

It's absolutely amazing to me that the official publication of this procedure could be so ambiguous! One look at a Jepp Chart tells the whole story. Since I can't post a referring link y'all are just gonna have to go look at a Jepp plate for this approach when you can.

In the profile section of a the Jepp plate what you see is that the segment between FOSOM and ESKOE has only one altitude associated with it - 2000'. It is labeled as mandatory. The answer is unambiguous and clear - the GSIA and the altitude to be maintained (mandatory) until GS intercept are both 2000'. End of story. It has nothing to do with whether you're on a localizer only approach or anything else. It is a per se requirement of ANY approach procedure that can be flown using the chart.

Most likely it serves to separate aircraft in the PHL terminal environment from aircraft in the terminal environment of some other nearby airport

I don't remember ever seeing a mandatory altitude at the FAF on any other ILS chart, looks to me like 2000 is the minimum alt. outside FOSOM, and 2000 is the mandatory alt. inside FOSOM until glideslope intercept or ESCOE for the LOC approach. Going to do some reading and see if that's correct.

Good keep reading because you should find that you're correct here. By the way, take a look at the OAK ILS 11. It too has a mandatory GSIA of 1800' and, being intimately familiar with this approach, I can tell you that a) you'd better be at that altitude well before GS intercept and NOT dawdling down the GS if you don't want to be copying a phone number after you land, and b) if that's not enough incentive, perhaps the TCAS RA or the wake turbulence encounter related to the 777 on the ILS 19R at SFO will convince you.

Edit: After looking at it again, I don't see why they would have the 2000 minimum altitude at glideslope intercept if 2000 was the manditory altitude, I think the 2000 manditory is only for the LOC approach.

D'ough! Ya blew it! You had it right the first time! Go find a Jepp chart and you'll see what I mean.

The reason there seem to be two different altitudes applicable to the situation is because the FAA's lovely way of charting things leaves them in this pickle. They feel the need to chart the GSIA and draw a little lightning bolt pointing to the intercept point. That point is always shown as an at-or-above altitude in terms of symbology - the numerical value with the line under it. If you think about it this would have to be the case. It's not going to be an at-or-below altitude with no lower limit!

They also have to show mandatory altitudes. They treat that as a separate exercise and thus, add another chart symbol - the same numerical value but this time with a line above and below it. This is what creates the confusion. Two symbols depicted when one would do - as long as there's a note that the said symbol is a mandatory altitude.

TIS

 

[TIS]

If it was intended to make you intercept the glide slope absolutely at 2000' over ESKOE, there would be a 2000 with lines above and below between FOSOM and ESKOE, instead of the 2000 with the below line and the lightning bolt.

I could be wrong though, I will have to look at the Jepps when I get in the airplane tomorrow.

Good! Go look at those Jepps. It'll clear it all up. The thing is that BOTH symbols you describe are there. One is to denote the intercept point (lightning bolt+altitude) and the other is to denote the mandatory altitude
(line above and below). They happen to be located in nearly the same place on the chart but they have nothing whatsoever to do with one another and they communicate separate, unrelated pieces on information.

TIS

 

[EatSleepFly]

One look at a Jepp Chart tells the whole story.

In the profile section of a the Jepp plate what you see is that the segment between FOSOM and ESKOE has only one altitude associated with it - 2000'. It is labeled as mandatory. The answer is unambiguous and clear - the GSIA and the altitude to be maintained (mandatory) until GS intercept are both 2000'. End of story.

Yep, what a difference. The Jepp chart is perfectly clear. I checked it out yesterday afternoon.

I'm glad we use Jepps...