JFK 22L VGSI and TCH

[extricate]

Hi there,

JFK or for some matter, some other airports as well, sometimes the VGSI TCH and GS TCH are different. In JFK 22L ILS, VGSI TCH is 66ft whereas GS TCH is 53ft, does it mean if I follow the G/S, the PAPI will become 3 reds at some point? Is my understanding correct? Even though the diff of 66ft and 53ft might not seem much.

Thanks for taking the time to reply.

With Regards

[PEI_3721]

See the thread / discussion at :-

https://www.pprune.org/tech-log/658480-ymml-meht.html

Oh, but that was your thread; so what exactly is the issue, what is not understood ?

[AerocatS2A]

See the thread / discussion at :-

https://www.pprune.org/tech-log/658480-ymml-meht.html

Oh, but that was your thread; so what exactly is the issue, what is not understood ?
I guess he didn’t like the answers, though they answered his question perfectly.

[Capn Bloggs]

does it mean if I follow the G/S, the PAPI will become 3 reds at some point?
Yes, fairly close in though.

13ft vertical is equivalent to 247ft long the runway. Have a play with my Glidepath spreadsheet here (https://docs.google.com/spreadsheets/d/1HfiSRyBK1Pj2-js9F1rWS_yNZn2nTSL2/edit?usp=sharing&ouid=114781885879885858690&rtpof=true&sd=true).

You can work out what you'll see using the angles of each light; assuming it's a PAPI:

https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/628x741/papi_design_angles_6711d4e7e855f8d8e38cd182e3ff73cb49d46252. jpg
That image came from this document:
https://web.archive.org/web/20230301152804/http://icscc.org.cn/upload/file/20220712/20220712090914_13813.pdf

[extricate]

Thanks for this. Let me take a look

[321XLR]

according to the AIM (indeed, not regulatory), a PAPI provides safe obstruction clearance within plus or minus 10 degrees of the extended runway centerline and to 3.4 NM from the runway threshold.

I am not a big PAPI guy, instead use the G/S or Vertical G/P, on the approach, until about 100 feet or so. Every time.

[Capn Bloggs]

a PAPI provides safe obstruction clearance within plus or minus 10 degrees of the extended runway centerline and to 3.4 NM from the runway threshold.
I suspect that means OUT TO. All the action happens approaching and under 1000ft so it would be pretty pointless having a system that is only supposed to be used outside 3.4nm. And they are certainly useable close-in. A quick glance when over the threshold would tell me if Bloggs was going to land long. ;)

[321XLR]

I suspect that means OUT TO. All the action happens approaching and under 1000ft so it would be pretty pointless having a system that is only supposed to be used outside 3.4nm. And they are certainly useable close-in. A quick glance when over the threshold would tell me if Bloggs was going to land long. ;)

I would hope they are usable close in