Capturing the localizer - Concorde X

[ryanbatc 12,815]

Well now were LUAW as well so everyone can be happy.

[VeryBumpy 272]

After doing some testing seems like the signal can be picked up at no more than 20 miles out. Perhaps some other airports are further, I don't know, been testing only at one airport.

 

The plane won't actually turn towards the airport and try to align itself until it is very near in front of the airport within maybe a 20 degree wide band.

[ryanbatc 12,815]

In FSX it is bugged... The localizer in real life can be intercepted many miles out, I believe 20 is correct for FSX.

 

As a rule of thumb, if perpendicular to the localizer, turn onto final at your ground speed divided by 100 miles. So if the localizer heading is 270 and you're flying 180 kts northbound, turn left heading 300 when you're 1.8 miles south of localizer.

 

For practice either use the default GPS or find a point of reference so you know how far you are from localizer.

[cptawsom 19]

After doing some testing seems like the signal can be picked up at no more than 20 miles out. Perhaps some other airports are further, I don't know, been testing only at one airport.

 

The plane won't actually turn towards the airport and try to align itself until it is very near in front of the airport within maybe a 20 degree wide band.

 

1. I believe the theoretical limit in FSX is 27nm.

 

2. Since the Concorde has no FMC, and no SID/STAR/Approach capability, include the most important waypoints of them in your INS flightplan. Most important, include the waypoint where the localizer is captured, and both the previous and next waypoints, for insurance.

 

For example, here is a flight I did a few days ago:

 

 

LGAV ABLON BISBA BGR CLE TEBLA BCN LEBL

 

 

Now if you look at the LEBL ILS25R chart, you will see that the point where the localizer is to be intercepted is along the straight-line segment defined by the points TEBLA+BCN, so there was no way I could miss it. I was in INS autopilot mode up until the last moment.

[VeryBumpy 272]

Yup, I did more testing tonight. Found 26 DME to be farthest the signal is picked up. So far, 21.5nm is the farthest that I've gotten the Concorde to actually 'lock on' and start turning towards the runway.

 

Also, with 3000ft altitude at 7.8nm out, the 'radio altimeters are active' message is announced and the plane starts to descend on the glide slope. I'm guessing this changes i.e. if I was higher this would happen sooner/farther out. Wonder if there is a max height limit to where the glide slope is started?

[ryanbatc 12,815]

Yes. It, too, has a service volume:

http://flyingdynamic...mplemention.htm

 

Another good illustration (scroll down)

http://www.cfiboretti.com/?page_id=377

[OldMaintChief 7]

Step 6 of my test flight outlined the ILS limits of FSX. Not quite the same as RW. How did it fly on the test flight?

 

Dave

[cptawsom 19]

Also, with 3000ft altitude at 7.8nm out, the 'radio altimeters are active' message is announced...

 

This has nothing to do with the glideslope capture. If you fly level at an altitude 2000ft above mount everest, the moments you pass directly above it, you will also hear that message.

 

I'm guessing this changes i.e. if I was higher this would happen sooner/farther out. Wonder if there is a max height limit to where the glide slope is started?

 

Yes. If there is no elevation (hills/mountains) to intercept the glideslope, it will.

 

In fact, there are several airport approach charts that have the official glideslope capture at 10 or 12 or even 15nm miles out at an altitude of even more than 4000ft.

 

In general, around flat areas, (eg Amsterdam, Dubai, etc.) you will be able to capture the glideslope much further away from what the charts describe.

[VeryBumpy 272]

This has nothing to do with the glideslope capture.

 

I guess I don't understand what that audio message is trying to tell me then?

[MachTwo 386]

"Radio Altimeters are active".

 

Concorde has two radio altimeters, one on the Captains instrument panel and one on the First Officer panel. They use radio waves emitted from instrumentation on the aircraft belly to bounce off the surface of the ground to measure the height of the aircraft above the ground.

 

The call out you hear by the Flight Engineer is made at 2500ft, to signify that the radio altimeters are showing a reading. Above 2500ft, the readings are masked.

 

The call out has nothing to do with the AFCS or ILS systems on the aircraft.

[VeryBumpy 272]

Ah, thank you for the info. Makes more sense now why this would announce very soon after the plane was descending from my usual 3000ft altitude.

 

Bit OT but did not know...

 

Barbara Harmer passes away - Feb 2011

BA's only female Concorde pilot has lost her battle with Cancer, she was 57.

The former hairdresser turned Captain was the first ever woman to pilot the aircraft, when she completed her conversion course in March 1993. She was the only woman in British Airways to pilot Concorde.