Displaced ILS question
Good one @basil....Lagos would be very much a preferred layover than LAX.....NOT!
My first/last time to Lagos was on an RAF VC10 carrying the pipe smoking PM Harold Wilson....I'm still trying to forget those days.
My first/last time to Lagos was on an RAF VC10 carrying the pipe smoking PM Harold Wilson....I'm still trying to forget those days.
Runway QFU is 203 and the FAT of ILS is 208.
Oh, and the RNAV approach has a very steep approach angle, recommended at 478 ft per nm, so what, about 4.5-5 degrees?
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Lydd warning
Training take-offs involving practice engine failure will not be allowed when using Runway 03 at any time, or when using
Runway 21 when a nuclear train is passing.
That's OK then....
glf
Runway 21 when a nuclear train is passing.
That's OK then....
glf
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Not sure BNFL or whoever they are now would be too worried about a light aircraft crashing into one of their nuclear trains:
Train test crash 1984 - nuclear flask test - YouTube
Train test crash 1984 - nuclear flask test - YouTube
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Re HKG:
. . and, if from the southwest and one didn't start the turn early to compensate, one would be blown through the centreline with very little opportunity to re-align 
The landing would become even more challenging when crosswinds from the northeast were strong
Thanks for the link Basil...crazy indeed. That was Korean Airlines and the windsock didn't look too full, but was from SW and across.
As an F/E I crewed on B707 for 4 years; 2 years on L1011 and 10 years on B747 and must have done that approach 100's of times and never had an incident...mind you...our pilots were supermen.
I know that because, in the aeroclub after landing, when we'd have a wind down drink before going home...they would often tell me so...
As an F/E I crewed on B707 for 4 years; 2 years on L1011 and 10 years on B747 and must have done that approach 100's of times and never had an incident...mind you...our pilots were supermen.
I know that because, in the aeroclub after landing, when we'd have a wind down drink before going home...they would often tell me so...
Looking at googlemaps, it would seem there is space off the end of the runway at Lydd for an inline localiser, but it's actually situated on the south east end of the disused runway, which leads me to suspect maybe the ground to the southwest was deemed too unstable to support it. I would think it is just topsoil overlaying shingle; certainly the water table can't be too far below the surface, so using a stable well drained foundation would seem logical.
The reason offset localisers are used at Sumburgh is simple; both ends of the runway are too close to the sea for an inline one to be positioned on land!
The reason offset localisers are used at Sumburgh is simple; both ends of the runway are too close to the sea for an inline one to be positioned on land!
in the aeroclub after landing, when we'd have a wind down drink before going home...they would often tell me so...
) but used to go into a UK club after final landing of the day; very flattering but needed the Roman triumph "hominem memento te" before the next approach in crap wx 
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While there are some interesting responses, clicker, I'm conscious that some of them have wandered away from your question. An IlLS is a precision approach which means the pilot gets guidance on glidepath and azimuth. The old Kai Tak IGS approach, for instance, wasn't an ILS approach at all; it merely used an ILS beam to allow the pilot to position for a visual landing.
In terms of your question about "kicking off" , what happens is the ILS guides the aircraft to a point (decision height) where the pilot will decide to land or goaround. For a modern airliner this might be the touchdown on the runway (CAT THREE). If the approach is offset, as at Lydd this will be higher to allow the pilot to align with the runway.
In terms of your question about "kicking off" , what happens is the ILS guides the aircraft to a point (decision height) where the pilot will decide to land or goaround. For a modern airliner this might be the touchdown on the runway (CAT THREE). If the approach is offset, as at Lydd this will be higher to allow the pilot to align with the runway.
As Shotone implies, if you couple an autopilot to an ILS and don't disconnect it at minimums, the aircraft will continue on its trajectory until it's nose wheel hits the runway piano-keys. The minimums on ILS are low (0-200ft depending on various factors) because the pilot does not need to make any configuration changes or alter the trajectory of the aircraft (except to flare) in order to complete the landing. This is why it is called an Instrument Landing System. The maximum runway non-alignment of an ILS is normally 3 degrees.
If the aircraft has to be manoeuvred visually by the pilot at minimums because the radio-beams are not aligned with the runway, then the approach is an IGS (such as Lugano which I mentioned, and the old Hong Kong approach). IGS means Instrument Guidance System. It uses the same ground and aircraft equipment as ILS, and the pilot flies it in exactly the same way as an ILS, except that at minimums he will have to visually manoeuvre the aircraft to land, and sometimes make configuration changes too (e.g. at Lugano the approach is so steep that I preferred to only select full flap once I was below minimums, aligned with centreline and on a 3 degree glidesope, even though this meant taking full flap much later than is normally sensible). The minimums of IGS are much higher to give the pilot altitude and time to correct the trajectory of the aircraft and make any configuration changes needed.
I haven't been to Lydd, but if the misalignment is 5 degrees, then possibly it should be classified as an IGS, as that would immediately flag up to the pilot the misalignment.
If the aircraft has to be manoeuvred visually by the pilot at minimums because the radio-beams are not aligned with the runway, then the approach is an IGS (such as Lugano which I mentioned, and the old Hong Kong approach). IGS means Instrument Guidance System. It uses the same ground and aircraft equipment as ILS, and the pilot flies it in exactly the same way as an ILS, except that at minimums he will have to visually manoeuvre the aircraft to land, and sometimes make configuration changes too (e.g. at Lugano the approach is so steep that I preferred to only select full flap once I was below minimums, aligned with centreline and on a 3 degree glidesope, even though this meant taking full flap much later than is normally sensible). The minimums of IGS are much higher to give the pilot altitude and time to correct the trajectory of the aircraft and make any configuration changes needed.
I haven't been to Lydd, but if the misalignment is 5 degrees, then possibly it should be classified as an IGS, as that would immediately flag up to the pilot the misalignment.
I'm not sure which is which now, but military airfields were allowed to use a max of 5 deg offset and ICAO was max 3 deg offset (or it could have been the other way round), but I believe military airfields shifted to ICAO calculated minima about 5 years ago, so the criteria is probably the same for both now.
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Good explanation trim stab but one adjustment; the ILS touchdown point is 450m along the runway not the piano keys, and even then, hopefully not on it's nose wheel.
I recall that ILS's were categorized depending on their accuracy. Cat1 to3C. Is it still the same?
A displaced ILS would have a higher minimum and 3C permitted autoland i.e. zero visibility.
I've been on board many autolands in practice and a few in earnest...I think Gatwick, or was it Heathrow, have autoland 3C.
The Autopilot does the flare and the auto-throttles control the thrust. The crews duty was to disengege and reverse and keep on the centre line.
Once I was a guest on a Belfast at RAF Brize Norton which I think used a leader cable system...it maintained the centre line with a roll-out mechanism of swirling horizontal mini-barbers poles which rotated at different speeds, showing which way to manouevre.
Anyone remember that system and how it worked?
A displaced ILS would have a higher minimum and 3C permitted autoland i.e. zero visibility.
I've been on board many autolands in practice and a few in earnest...I think Gatwick, or was it Heathrow, have autoland 3C.
The Autopilot does the flare and the auto-throttles control the thrust. The crews duty was to disengege and reverse and keep on the centre line.
Once I was a guest on a Belfast at RAF Brize Norton which I think used a leader cable system...it maintained the centre line with a roll-out mechanism of swirling horizontal mini-barbers poles which rotated at different speeds, showing which way to manouevre.
Anyone remember that system and how it worked?
Good explanation trim stab but one adjustment; the ILS touchdown point is 450m along the runway not the piano keys, and even then, hopefully not on it's nose wheel.
Obviously, if you flare, you will land on your main gear further down the runway. Not sure where you get the 450m figure from though.
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Offset ILS
Dusting off the old FI hat, I think that an instrument approach can only be an ILS if the Localiser is offset 3 degrees or less. If the offset is more than 3 degrees it becomes a localizer type directional aid (LDA) with a higher MDA/MDH. An offset ILS set up so that an aircraft on the ILS centre line and glide path crosses the extended runway centreline at DA/DH.
We operated the B757/767 to Cat 3C with no DH and an RVR of 75m (really just so we could see to taxi in) which brings me nicely to the leader cable idea.
We had a leader cable housing on the RAF Argosy in the sixties but never used it. I suspect trials may have been carried out but it wasn't introduced into general service. Would have been great in very poor vis with ATC monitoring ground movement radar and operating the points
We had a leader cable housing on the RAF Argosy in the sixties but never used it. I suspect trials may have been carried out but it wasn't introduced into general service. Would have been great in very poor vis with ATC monitoring ground movement radar and operating the points