length of ILS approach
 

One for the planners.. What determins the length of an approach slope of an ILS approach?. Apart from the hieght above the ground from which it is started? I am looking in particular at EGLF, rwy 24 is 4.7d and 06 is 6d. I can sort of understand why 24 is short (proximity of LTMA to the east), but why is 06 longer ?

I am not understanding your question.
Both approach plates show a final approach fix at 4.4 DME and both have a 3.5 degree glideslope which is a little steeper then the standard 3 degrees.

https://www.platinumairways.org/files/EGLFCharts.pdf

I would assume you can find the answer to your question in Doc 8168 PANS-OPS.

Those charts are very interesting, but are 6 years old. Latest Jepps show 6 and 4.7d

Rarely have I ever found a needle amongst that haystack.

Doc 8168 PANS-OPS simly states it can be between 3 and 10 miles for a 3 degree slope. IT does not say what determines the length of the final segment. EGLF is 3.5 degrees for both approaches.

What about
Vol. II Construction of Visual and Instrument Flight Procedures
Section 4. Arrival and approach procedures
Chapter 4. Intermediate approach segment
4.2 Altitude/height selection

possibly
Chapter 5. Final approach segment

The length of the intermediate approach segment shall not be ... less than 9.3 km (5.0 NM)

To fit a least the minimum I.A.S in tight airspace, obviously, the final segment might need to be shortened. OP suggested already,

More towards the question asked:

Personally (EU roots, busy hubs) I found 7, or even 9 NM more convenient. Most probably that SOPs had been built around those. One idea left at the moment = noise footprint.

My guess would be the MSA to the west is 2300 and to the east the control steps.

:O
Sorry didn’t check the date lol.
I can only assume it has to do with an obstacle clearance requirement.
WAG.

It looks to me that in this case it is for airspace containment purposes; the granted CTA's to EGLF would be as small as feasible, consistent with the purpose that the CAS is in place for in the first place. This reduces the impact on nearby aerodromes/aviation users.
The FAF being at the points where they are ensure that aircraft on the ILS will remain 500ft above the base of CAS of the various stepped down airspaces, whilst following the ILS profile down into the CTR.

Not obviously related to obstacles, as EGLF SMAC chart still has lower levels available (in theory), say if one was arriving/transitting IFR from outside CAS.

You also have to remember that aircraft must be vectored to enable them to establish and stabilise on the localiser a MINIMUM of 2nm before glidepath intercept and aircraft must be vectored not less than 2nm inside the boundary of CAS
I originally designed the Farnborough procedures to use alt 1,900ft as the 'platform' altitude but for some reason since I retired, the've been using a higher altitude; it was 2,400ft before CAS but what they use now I don't know.

That's because I designed the procedures for a platform altitude of 1,900ft and 4.4nm equals glidepath intercept at that altitude.
We could have dropped the 24 glidepath to 3 deg but the Airport Director and I (then a retired Air Commodore) decided that it was best not to as we had enough trouble with NIMBYs already; if they found out that aircraft were to pass 25ft or so lower over their homes, they would have been yelling for another public inquiry.
But don't let on; I didn't tell you that anyway.

Jepp charts are immaterial; according to the UK Flight Safety Committee, they are not checked or regulated by an independent source, so the only definitive charts are those in the UK AIP.
The reason for the difference is that the platform altitude on runway 06 post CAS is alt 2,500ft whereas on 24 it's 2,000ft, the '6' and '4.7' representing glidepath intercept ranges.

I always understood the steeper glidepath angle was to avoid "Cody's Tree".

How many operators or pilots use AIP charts in their flightdecks in lue of Jeppesen/LIDO/NavBlue?

True in real life. On the hair-splitting side: How many operators or pilots who use Jeppesen/LIDO/NavBlue charts in their flightdecks have read the small print on the Supplier's Disclaimer attachment to the sales contract?

As long as updated 3rd party package is a far fetch, and the AIP pages have all the information you'd need, it never hurts to drink from the source. It's free too.

Not since it was 'stolen' by DRA/DERA/Qinetiq and moved to Cody Site about a mile to the northwest.
3.5 deg GPs were adopted due to a design system called 'APATC-1' which was mandated for MOD airfields back in the '80s.
This involved a different way of calculating approach minima compared to the ICAO method used for civil airfelds, the 'dominant obsatcle' on runway 24 being --- the control tower!!
Once that was demolished in early 2003, we could have reduced to a 3 deg GP under both APATC-1 and ICAO methods of iap design.

https://cimg8.ibsrv.net/gimg/pprune....60bc034179.png

Recent. #gotitfromafriend

All true. Apart from the actual operating minima, that is :)