Inverted ILS
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From: UK
Inverted ILS
This has been bugging me for a few days. Ignoring the reasons of how and why you got there in the first place, if you were in inverted flight on an ILS would any of the LOC G/S commands be in the correct sense?
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From: Standby...call you back..
Not really interested to experience this kind of approach..
anyway..I'm pretty sure that the corrections will be made toward the correct way..this according to the electronically concept..Now..Hope for you that the GS antenna is not located around the main gear...in that specific case..only your shoes will appreciate the threshold !! the rest..
anyway..I'm pretty sure that the corrections will be made toward the correct way..this according to the electronically concept..Now..Hope for you that the GS antenna is not located around the main gear...in that specific case..only your shoes will appreciate the threshold !! the rest..
Last edited by roljoe; 27th May 2009 at 20:38.
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From: flyover country USA
A more complete explanation:
You are on approach, high and to the right of C/L, and you perform a 360 aileron roll while maintaining this track. The needles will not move during the roll; the LOC & GS antennae do not care about the airplane's attitude.
Well, almost.
Both antennas, being dipoles, will be at cross-polarization at the 90 and 270 points during the roll, and so signal strength will fall off for a second, and the needle displacements may decrease at these points. It may not even be noticeable, though.
You are on approach, high and to the right of C/L, and you perform a 360 aileron roll while maintaining this track. The needles will not move during the roll; the LOC & GS antennae do not care about the airplane's attitude.
Well, almost.
Both antennas, being dipoles, will be at cross-polarization at the 90 and 270 points during the roll, and so signal strength will fall off for a second, and the needle displacements may decrease at these points. It may not even be noticeable, though.
Joined: Jan 2005
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From: France
An explanation referrring back to ancient history, a bit simplified...
The ancient Lorenz approach system worked by transmitting two beams, one slightly to one side of the runway, modulated with dots, and one to the other side, modulated with dashes. If you were on the centre line, dots and dashes merged into a continuous tone.
The moment you can visualise this, you'll see that the attitude of the plane (even inverted) had nothing to do with it. If you were on the 'dots' side, you'd hear dots even with your head down.
The LOC and G/S system works somewhat differently... but the principle remains the same, it shows your position relative to the runway centre line and glidepath.
Now the kicker.... if you fly upside down, and hence you've turned the instrument upside down (think of the old Zero Reader), of course the indication is the wrong way round as welll
Think about it...
In normal flight, if the LOC needle is to the left, you turn to the left (towards the needle) to get back on the centreline.
In inverted flight, if the LOC needle is to the left, you now have to turn to the right to get back on the centreline.
Have fun.
CJ
The ancient Lorenz approach system worked by transmitting two beams, one slightly to one side of the runway, modulated with dots, and one to the other side, modulated with dashes. If you were on the centre line, dots and dashes merged into a continuous tone.
The moment you can visualise this, you'll see that the attitude of the plane (even inverted) had nothing to do with it. If you were on the 'dots' side, you'd hear dots even with your head down.
The LOC and G/S system works somewhat differently... but the principle remains the same, it shows your position relative to the runway centre line and glidepath.
Now the kicker.... if you fly upside down, and hence you've turned the instrument upside down (think of the old Zero Reader), of course the indication is the wrong way round as welll
Think about it...
In normal flight, if the LOC needle is to the left, you turn to the left (towards the needle) to get back on the centreline.
In inverted flight, if the LOC needle is to the left, you now have to turn to the right to get back on the centreline.
Have fun.
CJ
Joined: Jan 2008
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From: LONDON
Is this a serious question or a **** take?
It will only have been a waste of time if nobody has learnt anything - if it adds value what is the problem with a theoretical situation ?
The true professional will be able to tell you what they dont know - the others have not realised that yet. Lets not discourage questions !
Joined: Feb 2004
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From: Australia
So, in summary...
The pointers would not move if you did a roll on the ILS, but you would have to turn in the opposite sense to centre the needle if you were off the centreline.
I knew there was a good reason for that Backcourse selection on my Standby Attitude Indicator!
The pointers would not move if you did a roll on the ILS, but you would have to turn in the opposite sense to centre the needle if you were off the centreline.
I knew there was a good reason for that Backcourse selection on my Standby Attitude Indicator!
Joined: Nov 2005
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From: right here
as far as i remember...
the LOC has two "coils" each side of the centerline, one called "yellow" at 90Hz and the other "blue" at 150Hz.
lets assume we're on ILS27, pointers centered and NOT inverted. now we're drifting off to the north. the LOC-pointer/needle moves to the left.
draw it on a piece of paper incl view to rwy and ils instrument.
then turn it up side down.
WHOA!
lets assume we're on ILS27, pointers centered and NOT inverted. now we're drifting off to the north. the LOC-pointer/needle moves to the left.
draw it on a piece of paper incl view to rwy and ils instrument.
then turn it up side down.
WHOA!
Joined: Feb 2005
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From: flyover country USA
draw it on a piece of paper incl view to rwy and ils instrument.
then turn it up side down.
WHOA!
then turn it up side down.
WHOA!
Pull to make trees & cars look smaller.
Pull some more, trees & cars look bigger still.
Or is it the other way 'round?
Joined: Jan 2005
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From: France
Originally Posted by barit1
Push to make trees & cars look bigger.
Pull to make trees & cars look smaller.
Pull some more, trees & cars look bigger still.
Or is it the other way 'round?
Pull to make trees & cars look smaller.
Pull some more, trees & cars look bigger still.
Or is it the other way 'round?
Which is precisely the subject of this topic!
CJ
Joined: Oct 2003
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From: If this is Tuesday, it must be?
A long, long time ago - in a galaxy far, far away - I was involved in this very exercise. Not, I hasten to add, in a transport category aircraft but a suitable steed. One chap did it as a sponsored fund raising exercise on a nice day with a safety pilot. I was involved with the planning of how it would work.
Bizarrely, the localiser works "normally". Needle left, you need to roll left - and push! The G/S works in reverse, high you need to "raise" the nose as you are looking at it and vice versa.
Those were the days when such things weren't frowned upon, but seen as useful training. Oh, well
- I was involved in this very exercise. Not, I hasten to add, in a transport category aircraft but a suitable steed. One chap did it as a sponsored fund raising exercise on a nice day with a safety pilot. I was involved with the planning of how it would work.Bizarrely, the localiser works "normally". Needle left, you need to roll left - and push! The G/S works in reverse, high you need to "raise" the nose as you are looking at it and vice versa.
Those were the days when such things weren't frowned upon, but seen as useful training. Oh, well
Joined: Nov 1999
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From: East side of OZ
A long, long time ago - in a galaxy far, far away
The way I did it was to takeoff and fly up the ILS at the upwind end of the runway and level off at 3,000' and accelerate and then at about 15dme perform half a loop, remaining on the LLZ, and re-intercept the G/S and then fly back down the ILS inverted.
As BizJetJock says the localiser appeared normal but the push/pull to stay on the G/S was reversed. The first couple of approaches were a bit of a challenge but after that were not too difficult. I never required any of my students to try flying one though. The B707 sim didn't know it didn't have inverted fuel and oil systems so it would fly around all day 'inverted'.
An interesting but rather pointless excercise which doubtless would have been more of a handfull if you were inverted and hanging in the straps.
Regards,
BH.
