What prevents the use of a multi-segment ILS for non-straight approaches?How precise is an ILS (Instrument landing system)?What's the preferred approach for a passenger jet?Precision Approach systems: Why is ILS used more frequently than PAR and MLS?Does ATC provide ILS frequency and course setting for the runway in use?Why are sidestep ILS minima not used in EASA-land? (specific example: EGKK)How do pilots estimate glideslope visually without PAPIs?Can crews hand-fly an RNP AR approach in IMC?Why wouldn't KJFK offer the ILS for 22L?Do different planes (category) aim differently in the 'final stages before flaring'?Did Kai Tak have a straight-in approach to runway 13 for higher-performance aircraft?

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What prevents the use of a multi-segment ILS for non-straight approaches?

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What prevents the use of a multi-segment ILS for non-straight approaches?


How precise is an ILS (Instrument landing system)?What's the preferred approach for a passenger jet?Precision Approach systems: Why is ILS used more frequently than PAR and MLS?Does ATC provide ILS frequency and course setting for the runway in use?Why are sidestep ILS minima not used in EASA-land? (specific example: EGKK)How do pilots estimate glideslope visually without PAPIs?Can crews hand-fly an RNP AR approach in IMC?Why wouldn't KJFK offer the ILS for 22L?Do different planes (category) aim differently in the 'final stages before flaring'?Did Kai Tak have a straight-in approach to runway 13 for higher-performance aircraft?













2












$begingroup$


An ILS, consisting of a localiser beam to provide lateral guidance (which can also be used on its own for a non-precision approach) and a glideslope beam to provide vertical guidance, is (currently) indispensable for precision approaches in IMC, but comes with a few disadvantages.



Chief among those is the fact that an ILS only supports approaches that are ramrod-straight all the way in from the outer marker, when such an approach path is often impossible or undesirable...



  • ...sometimes because something too solid to fly through is in the way (for instance, the infamous approach to runway 13 at Kai Tak, which, due to an inconveniently-placed mountain, necessitated coming in at a large angle to the runway and then making a sharp right turn at very low altitude at almost literally the last moment; an instrument guidance system - basically an ILS without the “landing” part - was added in the 1970s to provide precision guidance for the part of the approach before the turn, but the turn itself and the final approach segment still had to be hand-flown visually, an exceptionally difficult task even in good weather)...

  • ...and sometimes because someone else is using part of the airspace in question (for instance, the four major airports in the New York area [JFK, la Guardia, Newark, and Teterboro] have numerous intersecting approach paths, which, as the approaches can’t be bent or segmented to keep out of each others’ way, frequently forces la Guardia and Teterboro to land aircraft on runways with strong crosswinds [because the ILS approach paths for their more optimal runways would risk causing MACs with aircraft on ILS approaches into JFK and/or Newark]; on the other side of the continent, the approach paths coming into LAX from the east pass near or over Ontario, which has caused quite a number of near misses in the vicinity of the latter airport).

It doesn’t seem, conceptually, like it should be too hard to break up an ILS approach into two or more segments, each with its own localiser and glideslope, and with the beams from the pre- and post-bend segments intersecting at the bend in the approach path. As most aircraft are unable to turn on a dime, they would need to start turning a bit before the bend in the approach, but this could be easily handled by having another instrumental aid (for instance, a third localiser) indicate when to start turning; if the bend in the approach were sharp enough for the aircraft to have trouble locking onto the post-bend beams, another localiser and glideslope, with their beams tangent to the midpoint of the turn, could be used to assist the aircraft round the bend.



All of this would also work for segmented localiser approaches, with the added advantage of being easier to implement (no need for the multiple glideslope antennae, just the localiser ones).



Here be an illustration of what I’ve got in mind:



Segmented ILS/localiser approach (actual size)



Why aren’t segmented ILS and localiser approaches used in practice?










share|improve this question









$endgroup$
















    2












    $begingroup$


    An ILS, consisting of a localiser beam to provide lateral guidance (which can also be used on its own for a non-precision approach) and a glideslope beam to provide vertical guidance, is (currently) indispensable for precision approaches in IMC, but comes with a few disadvantages.



    Chief among those is the fact that an ILS only supports approaches that are ramrod-straight all the way in from the outer marker, when such an approach path is often impossible or undesirable...



    • ...sometimes because something too solid to fly through is in the way (for instance, the infamous approach to runway 13 at Kai Tak, which, due to an inconveniently-placed mountain, necessitated coming in at a large angle to the runway and then making a sharp right turn at very low altitude at almost literally the last moment; an instrument guidance system - basically an ILS without the “landing” part - was added in the 1970s to provide precision guidance for the part of the approach before the turn, but the turn itself and the final approach segment still had to be hand-flown visually, an exceptionally difficult task even in good weather)...

    • ...and sometimes because someone else is using part of the airspace in question (for instance, the four major airports in the New York area [JFK, la Guardia, Newark, and Teterboro] have numerous intersecting approach paths, which, as the approaches can’t be bent or segmented to keep out of each others’ way, frequently forces la Guardia and Teterboro to land aircraft on runways with strong crosswinds [because the ILS approach paths for their more optimal runways would risk causing MACs with aircraft on ILS approaches into JFK and/or Newark]; on the other side of the continent, the approach paths coming into LAX from the east pass near or over Ontario, which has caused quite a number of near misses in the vicinity of the latter airport).

    It doesn’t seem, conceptually, like it should be too hard to break up an ILS approach into two or more segments, each with its own localiser and glideslope, and with the beams from the pre- and post-bend segments intersecting at the bend in the approach path. As most aircraft are unable to turn on a dime, they would need to start turning a bit before the bend in the approach, but this could be easily handled by having another instrumental aid (for instance, a third localiser) indicate when to start turning; if the bend in the approach were sharp enough for the aircraft to have trouble locking onto the post-bend beams, another localiser and glideslope, with their beams tangent to the midpoint of the turn, could be used to assist the aircraft round the bend.



    All of this would also work for segmented localiser approaches, with the added advantage of being easier to implement (no need for the multiple glideslope antennae, just the localiser ones).



    Here be an illustration of what I’ve got in mind:



    Segmented ILS/localiser approach (actual size)



    Why aren’t segmented ILS and localiser approaches used in practice?










    share|improve this question









    $endgroup$














      2












      2








      2


      1



      $begingroup$


      An ILS, consisting of a localiser beam to provide lateral guidance (which can also be used on its own for a non-precision approach) and a glideslope beam to provide vertical guidance, is (currently) indispensable for precision approaches in IMC, but comes with a few disadvantages.



      Chief among those is the fact that an ILS only supports approaches that are ramrod-straight all the way in from the outer marker, when such an approach path is often impossible or undesirable...



      • ...sometimes because something too solid to fly through is in the way (for instance, the infamous approach to runway 13 at Kai Tak, which, due to an inconveniently-placed mountain, necessitated coming in at a large angle to the runway and then making a sharp right turn at very low altitude at almost literally the last moment; an instrument guidance system - basically an ILS without the “landing” part - was added in the 1970s to provide precision guidance for the part of the approach before the turn, but the turn itself and the final approach segment still had to be hand-flown visually, an exceptionally difficult task even in good weather)...

      • ...and sometimes because someone else is using part of the airspace in question (for instance, the four major airports in the New York area [JFK, la Guardia, Newark, and Teterboro] have numerous intersecting approach paths, which, as the approaches can’t be bent or segmented to keep out of each others’ way, frequently forces la Guardia and Teterboro to land aircraft on runways with strong crosswinds [because the ILS approach paths for their more optimal runways would risk causing MACs with aircraft on ILS approaches into JFK and/or Newark]; on the other side of the continent, the approach paths coming into LAX from the east pass near or over Ontario, which has caused quite a number of near misses in the vicinity of the latter airport).

      It doesn’t seem, conceptually, like it should be too hard to break up an ILS approach into two or more segments, each with its own localiser and glideslope, and with the beams from the pre- and post-bend segments intersecting at the bend in the approach path. As most aircraft are unable to turn on a dime, they would need to start turning a bit before the bend in the approach, but this could be easily handled by having another instrumental aid (for instance, a third localiser) indicate when to start turning; if the bend in the approach were sharp enough for the aircraft to have trouble locking onto the post-bend beams, another localiser and glideslope, with their beams tangent to the midpoint of the turn, could be used to assist the aircraft round the bend.



      All of this would also work for segmented localiser approaches, with the added advantage of being easier to implement (no need for the multiple glideslope antennae, just the localiser ones).



      Here be an illustration of what I’ve got in mind:



      Segmented ILS/localiser approach (actual size)



      Why aren’t segmented ILS and localiser approaches used in practice?










      share|improve this question









      $endgroup$




      An ILS, consisting of a localiser beam to provide lateral guidance (which can also be used on its own for a non-precision approach) and a glideslope beam to provide vertical guidance, is (currently) indispensable for precision approaches in IMC, but comes with a few disadvantages.



      Chief among those is the fact that an ILS only supports approaches that are ramrod-straight all the way in from the outer marker, when such an approach path is often impossible or undesirable...



      • ...sometimes because something too solid to fly through is in the way (for instance, the infamous approach to runway 13 at Kai Tak, which, due to an inconveniently-placed mountain, necessitated coming in at a large angle to the runway and then making a sharp right turn at very low altitude at almost literally the last moment; an instrument guidance system - basically an ILS without the “landing” part - was added in the 1970s to provide precision guidance for the part of the approach before the turn, but the turn itself and the final approach segment still had to be hand-flown visually, an exceptionally difficult task even in good weather)...

      • ...and sometimes because someone else is using part of the airspace in question (for instance, the four major airports in the New York area [JFK, la Guardia, Newark, and Teterboro] have numerous intersecting approach paths, which, as the approaches can’t be bent or segmented to keep out of each others’ way, frequently forces la Guardia and Teterboro to land aircraft on runways with strong crosswinds [because the ILS approach paths for their more optimal runways would risk causing MACs with aircraft on ILS approaches into JFK and/or Newark]; on the other side of the continent, the approach paths coming into LAX from the east pass near or over Ontario, which has caused quite a number of near misses in the vicinity of the latter airport).

      It doesn’t seem, conceptually, like it should be too hard to break up an ILS approach into two or more segments, each with its own localiser and glideslope, and with the beams from the pre- and post-bend segments intersecting at the bend in the approach path. As most aircraft are unable to turn on a dime, they would need to start turning a bit before the bend in the approach, but this could be easily handled by having another instrumental aid (for instance, a third localiser) indicate when to start turning; if the bend in the approach were sharp enough for the aircraft to have trouble locking onto the post-bend beams, another localiser and glideslope, with their beams tangent to the midpoint of the turn, could be used to assist the aircraft round the bend.



      All of this would also work for segmented localiser approaches, with the added advantage of being easier to implement (no need for the multiple glideslope antennae, just the localiser ones).



      Here be an illustration of what I’ve got in mind:



      Segmented ILS/localiser approach (actual size)



      Why aren’t segmented ILS and localiser approaches used in practice?







      approach ils localizer






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked 5 hours ago









      SeanSean

      5,34432667




      5,34432667




















          1 Answer
          1






          active

          oldest

          votes


















          2












          $begingroup$

          See here, pages 5-23, 5-24. Things have advanced well beyond ILS for that kind of approach.



          https://whispertrack.com/pdf/faa_handbook.pdf




          REQUIRED NAVIGATION PERFORMANCE
          The operational advantages of RNP include accuracy
          and integrity monitoring, which provide more precision and lower minimums than conventional RNAV.
          RNP DAs can be as low as 250 feet with visibilities as
          low as 3/4 SM. Besides lower minimums, the benefits
          of RNP include improved obstacle clearance limits, as
          well as reduced pilot workload. When RNP-capable
          aircraft fly an accurate, repeatable path, ATC can be
          confident that these aircraft will be at a specific position, thus maximizing safety and increasing capacity



          To attain the benefits of RNP approach procedures, a
          key component is curved flight tracks. Constant radius
          turns around a fix are called “radius-to-fix legs,” or RF
          legs. These turns, which are encoded into the navigation database, allow the aircraft to avoid critical areas
          of terrain or conflicting airspace while preserving positional accuracy by maintaining precise, positive course
          guidance along the curved track. The introduction of
          RF legs into the design of terminal RNAV procedures
          results in improved use of airspace and allows procedures to be developed to and from runways that are otherwise limited to traditional linear flight paths or, in
          some cases, not served by an IFR procedure at all.
          Navigation systems with RF capability are a prerequisite to flying a procedure that includes an RF leg. Refer
          to the notes box of the pilot briefing portion of the
          approach chart in figure 5-17.




          The Approach in Fig 5-17 has 5 turns left & right!






          share|improve this answer









          $endgroup$












            Your Answer





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            1 Answer
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            active

            oldest

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            active

            oldest

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            2












            $begingroup$

            See here, pages 5-23, 5-24. Things have advanced well beyond ILS for that kind of approach.



            https://whispertrack.com/pdf/faa_handbook.pdf




            REQUIRED NAVIGATION PERFORMANCE
            The operational advantages of RNP include accuracy
            and integrity monitoring, which provide more precision and lower minimums than conventional RNAV.
            RNP DAs can be as low as 250 feet with visibilities as
            low as 3/4 SM. Besides lower minimums, the benefits
            of RNP include improved obstacle clearance limits, as
            well as reduced pilot workload. When RNP-capable
            aircraft fly an accurate, repeatable path, ATC can be
            confident that these aircraft will be at a specific position, thus maximizing safety and increasing capacity



            To attain the benefits of RNP approach procedures, a
            key component is curved flight tracks. Constant radius
            turns around a fix are called “radius-to-fix legs,” or RF
            legs. These turns, which are encoded into the navigation database, allow the aircraft to avoid critical areas
            of terrain or conflicting airspace while preserving positional accuracy by maintaining precise, positive course
            guidance along the curved track. The introduction of
            RF legs into the design of terminal RNAV procedures
            results in improved use of airspace and allows procedures to be developed to and from runways that are otherwise limited to traditional linear flight paths or, in
            some cases, not served by an IFR procedure at all.
            Navigation systems with RF capability are a prerequisite to flying a procedure that includes an RF leg. Refer
            to the notes box of the pilot briefing portion of the
            approach chart in figure 5-17.




            The Approach in Fig 5-17 has 5 turns left & right!






            share|improve this answer









            $endgroup$

















              2












              $begingroup$

              See here, pages 5-23, 5-24. Things have advanced well beyond ILS for that kind of approach.



              https://whispertrack.com/pdf/faa_handbook.pdf




              REQUIRED NAVIGATION PERFORMANCE
              The operational advantages of RNP include accuracy
              and integrity monitoring, which provide more precision and lower minimums than conventional RNAV.
              RNP DAs can be as low as 250 feet with visibilities as
              low as 3/4 SM. Besides lower minimums, the benefits
              of RNP include improved obstacle clearance limits, as
              well as reduced pilot workload. When RNP-capable
              aircraft fly an accurate, repeatable path, ATC can be
              confident that these aircraft will be at a specific position, thus maximizing safety and increasing capacity



              To attain the benefits of RNP approach procedures, a
              key component is curved flight tracks. Constant radius
              turns around a fix are called “radius-to-fix legs,” or RF
              legs. These turns, which are encoded into the navigation database, allow the aircraft to avoid critical areas
              of terrain or conflicting airspace while preserving positional accuracy by maintaining precise, positive course
              guidance along the curved track. The introduction of
              RF legs into the design of terminal RNAV procedures
              results in improved use of airspace and allows procedures to be developed to and from runways that are otherwise limited to traditional linear flight paths or, in
              some cases, not served by an IFR procedure at all.
              Navigation systems with RF capability are a prerequisite to flying a procedure that includes an RF leg. Refer
              to the notes box of the pilot briefing portion of the
              approach chart in figure 5-17.




              The Approach in Fig 5-17 has 5 turns left & right!






              share|improve this answer









              $endgroup$















                2












                2








                2





                $begingroup$

                See here, pages 5-23, 5-24. Things have advanced well beyond ILS for that kind of approach.



                https://whispertrack.com/pdf/faa_handbook.pdf




                REQUIRED NAVIGATION PERFORMANCE
                The operational advantages of RNP include accuracy
                and integrity monitoring, which provide more precision and lower minimums than conventional RNAV.
                RNP DAs can be as low as 250 feet with visibilities as
                low as 3/4 SM. Besides lower minimums, the benefits
                of RNP include improved obstacle clearance limits, as
                well as reduced pilot workload. When RNP-capable
                aircraft fly an accurate, repeatable path, ATC can be
                confident that these aircraft will be at a specific position, thus maximizing safety and increasing capacity



                To attain the benefits of RNP approach procedures, a
                key component is curved flight tracks. Constant radius
                turns around a fix are called “radius-to-fix legs,” or RF
                legs. These turns, which are encoded into the navigation database, allow the aircraft to avoid critical areas
                of terrain or conflicting airspace while preserving positional accuracy by maintaining precise, positive course
                guidance along the curved track. The introduction of
                RF legs into the design of terminal RNAV procedures
                results in improved use of airspace and allows procedures to be developed to and from runways that are otherwise limited to traditional linear flight paths or, in
                some cases, not served by an IFR procedure at all.
                Navigation systems with RF capability are a prerequisite to flying a procedure that includes an RF leg. Refer
                to the notes box of the pilot briefing portion of the
                approach chart in figure 5-17.




                The Approach in Fig 5-17 has 5 turns left & right!






                share|improve this answer









                $endgroup$



                See here, pages 5-23, 5-24. Things have advanced well beyond ILS for that kind of approach.



                https://whispertrack.com/pdf/faa_handbook.pdf




                REQUIRED NAVIGATION PERFORMANCE
                The operational advantages of RNP include accuracy
                and integrity monitoring, which provide more precision and lower minimums than conventional RNAV.
                RNP DAs can be as low as 250 feet with visibilities as
                low as 3/4 SM. Besides lower minimums, the benefits
                of RNP include improved obstacle clearance limits, as
                well as reduced pilot workload. When RNP-capable
                aircraft fly an accurate, repeatable path, ATC can be
                confident that these aircraft will be at a specific position, thus maximizing safety and increasing capacity



                To attain the benefits of RNP approach procedures, a
                key component is curved flight tracks. Constant radius
                turns around a fix are called “radius-to-fix legs,” or RF
                legs. These turns, which are encoded into the navigation database, allow the aircraft to avoid critical areas
                of terrain or conflicting airspace while preserving positional accuracy by maintaining precise, positive course
                guidance along the curved track. The introduction of
                RF legs into the design of terminal RNAV procedures
                results in improved use of airspace and allows procedures to be developed to and from runways that are otherwise limited to traditional linear flight paths or, in
                some cases, not served by an IFR procedure at all.
                Navigation systems with RF capability are a prerequisite to flying a procedure that includes an RF leg. Refer
                to the notes box of the pilot briefing portion of the
                approach chart in figure 5-17.




                The Approach in Fig 5-17 has 5 turns left & right!







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered 3 hours ago









                CrossRoadsCrossRoads

                4,9101819




                4,9101819



























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