ILS intercept height.

[NacelleStrake]

At what height does a modern jet transport intercept the ILS. That's the 3 degree angle bit. Is there an 'optimum' height for this. I've read, on here, that it's intercepted from 'below?'

[HEATHROW DIRECTOR]

Modern airliners like to be established on the ILS by around 8-10nm from touchdown. Ideally they should approach the glidepath from below but at busy airfields this may be difficult to achieve.

[BOAC]

but at busy airfields this may be difficult to achieve. - tut tut. 'Sharpen up Carruthers!'

As 411A used to say "if you can't stand the heat......................" Even AMS can do it (admittedly with about 100m to spare:))

[chevvron]

It's an ICAO and CAA requirement that aircraft should (not must) be established and stabilised on the localiser 2nm before glidepath intercept.

[NacelleStrake]

Thnx for the expeditious feedback chaps. Therefore, the aircraft ought to be established on the LOC before intercepting the GS. This would be around 3-3500ft?

[HEATHROW DIRECTOR]

BOAC.. It's quite difficult to achieve, especially with parallel landings in IMC!

[PPRuNeUser0179]

most modern jets IE(B737-CRJ2/700-A319-A321 etc etc) are established about 10NM out and only then intercept the GS once established...this is all done at around 3000ft...if it is IMC and a hec load of traffic,special permissions are granted with the ILS procedures.
This is at East London airport,South Africa (ICAO-FAEL).CAA Website (http://www.caa.co.za) for charts.

[Flying Wild]

It varies from airport to airport. For example CDG has an intercept for 27R of 5000' altitude, which is about 4500' AGL

[HEATHROW DIRECTOR]

So all aircraft landing at CDG lock on at 15nm?

[BOAC]

Yup - and often further out and are sometimes cleared to land no 3 at 15 nm................. it's a big wide world!.

[gorter]

I have been cleared for the approach at 40nm previously whilst on a nominal localiser. Remained in heading mode until 23 miles and v/s until 17.

[grounded27]

Loc is allways aquired first and it is generally a matter of how good the tx/rx is. G/S 2nd then usually requires an input from the radio or radar altimerer (usually at 1500' agl) so the aircraft can perform a confidence check of the approach path/system integrity verified followed by approval for land mode.