ILS & Nav1-Radio at London Heathrow: Same freq for opposite RWYs?

[Guest Cantuezel]

Hi,I have a short question concerning the ILS- radio system at London Heathrow. I took off with the PMDG on RWY 27R (274 HDG) and wanted to fly a racing-pattern to approach ILS 27R again. After being airborn (still RWY heading) I looked up the Freq for ILS27R (IRR), the charts says 110.30 MhZ. So I tuned the Freq in Nav1. But then something strange happened: The PFD didn`t say IRR and 294 degrees HDG but instead IAA and 094, that is the Code for ILS 09L! So I looked in the charts again for the Freqs and really: The same freq for ILS09L and ILS 27R...110.30 MhZ..!I decided to fly on (I thought that RWY 27R only have kind of a backbeam approach)...when I was abeam of the RWY the PFD suddenly changed and then said the correct IRR-code and 274 HDG...I landed without any problems...My questions: 1) How can this be: One Freq for *two* Glide-paths? How does the Nav1-transmitter recognizes which RWY I approach (modulation etc...)? 2) Why doesn`t the airport authorities at Heathrow use different Freqs for every ILS-RWY instead of using the same one for the opposite directions? Do you have any idea?3) Isn`t that tricky for a pilot in real life when approaching a RWY in minimum weather conditions and then having that kind of "strange" display at the PFD for the ILS idetification-code?4) Is that common in the (western) world (Europe, US etc.)...I mean to use *one* single freq for opposite Glide-paths transmission?Many thanks in advance! :)GreetingsSusan

[Guest ahmedem]

Hey Susan,1)It's quite common to have for runways with the ILS equipped in both directions to have the same frequency. You will find that 109.5 will tune for both ILS09R and ILS27L. I'm not to familiar with ILS equipment on the ground but I believe that it is the same transmitter shooting a LOC and G/S is both directions.2)There is no need.3)Its not tricky for the pilots because a)they know where they are and :( the ILS is identified by its 3 letter identifier IAA or IRR etc.4)very very common indeed. In fact its uncommon to find it any other way, anywhere in the world.Rgds,

[Guest tmetzinger]

In real life, in the US, the tower controller has a switch which activates one transmitter or the others - there's never two localizers on the same frequency active at the same time.In FS9, the sim software detects your position relative to the runway and you see the correct localizer.Identifications in morse are always different, which is why you need to audibly verify them or let the airplane verify which localizer you're tracking.

[Guest ahmedem]

Ah and there I was getting mislead by Microsoft thinking they were both on simultaneously. Thanks for setting me straight on that Tim.

[Guest Cantuezel]

Thanks guys for that really fast answers...! :)@TimVery interesting! I never heard of that before...it seems to much flying *only* with MS-FS isn`t to good...:)GreetingsSusan