length of ILS approach
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'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.'
You seem to be a man who knows what your talking about Chevron.. So why the diference in platform altitudes?. if you designed it at 1900' why the change to 2500'?
You seem to be a man who knows what your talking about Chevron.. So why the diference in platform altitudes?. if you designed it at 1900' why the change to 2500'?
They changed to 2,400ft intially just after I retired back in 2008; dunno why because the system we used before that was to vector the IFR inbound at 1,900ft and keep any transits at 2,400ft passing traffic information to both aircraft so you didn't then have to try to 'control' a VFR transit to enable you to descend the IFR inbound through it when it was on the ILS.
I can understand using 2,500ft on 06 now they have CAS in order to stay above Odiham traffic, but why 2000ft on 24 I don't know especially as the base of their CTA is 2,000ft just south of Fairoaks and they're supposed to keep IFR traffic at least 500ft above the base.
I can understand using 2,500ft on 06 now they have CAS in order to stay above Odiham traffic, but why 2000ft on 24 I don't know especially as the base of their CTA is 2,000ft just south of Fairoaks and they're supposed to keep IFR traffic at least 500ft above the base.
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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.
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.
Its introduction resulted in a rethink and a lot of discussion about how we calculated our approach minima. The “En Route Supplement” contained a few anomalies, especially as the RAF flew instrument approaches on QFE. I remember ringing ATC at an airfield not far away to try to ascertain if the minima published in the “Red book” was calculated on QFE or QNH, because there was only a single figure stated, rather than the two quoted for other airfields. We were rather astonished to hear that the ATCO didn’t know!
We didn't. We were told to refer to it a 'Procedure Minima' eg 'vectoring for PAR approach to runway 28, procedure minima is 'XXX', confirm decision height and intention'.
Some years later we did get 2 sets of minima when, with much fanfare, QNH based procedures were introduced. My boss and I attended a combined briefing for Odiham and Farnborugh ATC units at Odiham where the inimitable Dave Harrison from No 1 AIDU gave us a thorough rundown.
A couple of years later, after what was rumoured to be a cock up by an 'elderly gentleman' mistaking QFE for QNH, the procedures were switched back to QFE based with no 'publicity' although for some reason, Farnborough ATC didn't receive the 'change' to JSP318a where it was notified and we were not told by other means so were mystified when our aircrew suddenly started asking for QFE before departure!
NB: If you're wondering why I put 'a type of dog up' I didn't, that's what Pprune software has changed what I actually typed ('a c0ck up').
Some years later we did get 2 sets of minima when, with much fanfare, QNH based procedures were introduced. My boss and I attended a combined briefing for Odiham and Farnborugh ATC units at Odiham where the inimitable Dave Harrison from No 1 AIDU gave us a thorough rundown.
A couple of years later, after what was rumoured to be a cock up by an 'elderly gentleman' mistaking QFE for QNH, the procedures were switched back to QFE based with no 'publicity' although for some reason, Farnborough ATC didn't receive the 'change' to JSP318a where it was notified and we were not told by other means so were mystified when our aircrew suddenly started asking for QFE before departure!
NB: If you're wondering why I put 'a type of dog up' I didn't, that's what Pprune software has changed what I actually typed ('a c0ck up').
