Vertical and horizontal separation between cruising and climbing aircraft












10














I was recently a passenger on a commercial aircraft at cruise altitude when I noticed another aircraft just reaching its cruising altitude while crossing our flightpath from below, at what looked like a very close distance.



I looked up the two flights (LH491, AC172 on Nov 10, 2018) on Flightradar 24, linearly interpolated the following values in Excel to roughly 2-3 seconds resolution, and calculated the great circle distance between the coordinates:



interpolated separation AC 172 and LH 491



AC 172 was heading 106° at the very end of its climb to FL 350. LH 491 was heading 51°, cruising at FL 350.



The smallest horizontal separation by my calculation was about 3.67 nm (at 1300 ft vertically). When we reached 1000 ft vertical separation, that distance was about 4.7 nm.



To my understanding, aircraft at these altitudes should always have a separation of least 1000 ft or 5 nm.



Not being an aviation professional myself, could someone please help me understand what was happening here?



I'm sure there must be a duplicate question, but I couldn't find one that involves both the vertical and horizontal components.










share|improve this question



























    10














    I was recently a passenger on a commercial aircraft at cruise altitude when I noticed another aircraft just reaching its cruising altitude while crossing our flightpath from below, at what looked like a very close distance.



    I looked up the two flights (LH491, AC172 on Nov 10, 2018) on Flightradar 24, linearly interpolated the following values in Excel to roughly 2-3 seconds resolution, and calculated the great circle distance between the coordinates:



    interpolated separation AC 172 and LH 491



    AC 172 was heading 106° at the very end of its climb to FL 350. LH 491 was heading 51°, cruising at FL 350.



    The smallest horizontal separation by my calculation was about 3.67 nm (at 1300 ft vertically). When we reached 1000 ft vertical separation, that distance was about 4.7 nm.



    To my understanding, aircraft at these altitudes should always have a separation of least 1000 ft or 5 nm.



    Not being an aviation professional myself, could someone please help me understand what was happening here?



    I'm sure there must be a duplicate question, but I couldn't find one that involves both the vertical and horizontal components.










    share|improve this question

























      10












      10








      10







      I was recently a passenger on a commercial aircraft at cruise altitude when I noticed another aircraft just reaching its cruising altitude while crossing our flightpath from below, at what looked like a very close distance.



      I looked up the two flights (LH491, AC172 on Nov 10, 2018) on Flightradar 24, linearly interpolated the following values in Excel to roughly 2-3 seconds resolution, and calculated the great circle distance between the coordinates:



      interpolated separation AC 172 and LH 491



      AC 172 was heading 106° at the very end of its climb to FL 350. LH 491 was heading 51°, cruising at FL 350.



      The smallest horizontal separation by my calculation was about 3.67 nm (at 1300 ft vertically). When we reached 1000 ft vertical separation, that distance was about 4.7 nm.



      To my understanding, aircraft at these altitudes should always have a separation of least 1000 ft or 5 nm.



      Not being an aviation professional myself, could someone please help me understand what was happening here?



      I'm sure there must be a duplicate question, but I couldn't find one that involves both the vertical and horizontal components.










      share|improve this question













      I was recently a passenger on a commercial aircraft at cruise altitude when I noticed another aircraft just reaching its cruising altitude while crossing our flightpath from below, at what looked like a very close distance.



      I looked up the two flights (LH491, AC172 on Nov 10, 2018) on Flightradar 24, linearly interpolated the following values in Excel to roughly 2-3 seconds resolution, and calculated the great circle distance between the coordinates:



      interpolated separation AC 172 and LH 491



      AC 172 was heading 106° at the very end of its climb to FL 350. LH 491 was heading 51°, cruising at FL 350.



      The smallest horizontal separation by my calculation was about 3.67 nm (at 1300 ft vertically). When we reached 1000 ft vertical separation, that distance was about 4.7 nm.



      To my understanding, aircraft at these altitudes should always have a separation of least 1000 ft or 5 nm.



      Not being an aviation professional myself, could someone please help me understand what was happening here?



      I'm sure there must be a duplicate question, but I couldn't find one that involves both the vertical and horizontal components.







      instrument-flight-rules separation






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      asked Nov 12 '18 at 21:31









      Daniel HutmacherDaniel Hutmacher

      1535




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          1 Answer
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          14














          I think you may have answered your own question note the use of the word OR




          To my understanding, aircraft at these altitudes should always have a
          separation of least 1000 ft or 5 nm.




          If you take a look at your data the aircraft are always separated by 1000 feet OR 5nm. The singular exception to this is when you have the separation quoted at 4.81 miles and 982ft. This can to an extent be explained away by the inaccuracies in systems like FlightRadar24






          share|improve this answer

















          • 3




            The separation of 982ft would also most likely not be "out of bounds" for the 1000ft rule, since ATC scopes only see increments of 100ft. Per the ATC data, the two aircraft were back into the 5+ horizontal separation range before they fell out of the 1000ft vertical separation range.
            – Jimmy
            Nov 12 '18 at 22:19











          Your Answer





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          1 Answer
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          1 Answer
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          active

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          active

          oldest

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          active

          oldest

          votes









          14














          I think you may have answered your own question note the use of the word OR




          To my understanding, aircraft at these altitudes should always have a
          separation of least 1000 ft or 5 nm.




          If you take a look at your data the aircraft are always separated by 1000 feet OR 5nm. The singular exception to this is when you have the separation quoted at 4.81 miles and 982ft. This can to an extent be explained away by the inaccuracies in systems like FlightRadar24






          share|improve this answer

















          • 3




            The separation of 982ft would also most likely not be "out of bounds" for the 1000ft rule, since ATC scopes only see increments of 100ft. Per the ATC data, the two aircraft were back into the 5+ horizontal separation range before they fell out of the 1000ft vertical separation range.
            – Jimmy
            Nov 12 '18 at 22:19
















          14














          I think you may have answered your own question note the use of the word OR




          To my understanding, aircraft at these altitudes should always have a
          separation of least 1000 ft or 5 nm.




          If you take a look at your data the aircraft are always separated by 1000 feet OR 5nm. The singular exception to this is when you have the separation quoted at 4.81 miles and 982ft. This can to an extent be explained away by the inaccuracies in systems like FlightRadar24






          share|improve this answer

















          • 3




            The separation of 982ft would also most likely not be "out of bounds" for the 1000ft rule, since ATC scopes only see increments of 100ft. Per the ATC data, the two aircraft were back into the 5+ horizontal separation range before they fell out of the 1000ft vertical separation range.
            – Jimmy
            Nov 12 '18 at 22:19














          14












          14








          14






          I think you may have answered your own question note the use of the word OR




          To my understanding, aircraft at these altitudes should always have a
          separation of least 1000 ft or 5 nm.




          If you take a look at your data the aircraft are always separated by 1000 feet OR 5nm. The singular exception to this is when you have the separation quoted at 4.81 miles and 982ft. This can to an extent be explained away by the inaccuracies in systems like FlightRadar24






          share|improve this answer












          I think you may have answered your own question note the use of the word OR




          To my understanding, aircraft at these altitudes should always have a
          separation of least 1000 ft or 5 nm.




          If you take a look at your data the aircraft are always separated by 1000 feet OR 5nm. The singular exception to this is when you have the separation quoted at 4.81 miles and 982ft. This can to an extent be explained away by the inaccuracies in systems like FlightRadar24







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 12 '18 at 22:04









          DaveDave

          62.2k4111227




          62.2k4111227








          • 3




            The separation of 982ft would also most likely not be "out of bounds" for the 1000ft rule, since ATC scopes only see increments of 100ft. Per the ATC data, the two aircraft were back into the 5+ horizontal separation range before they fell out of the 1000ft vertical separation range.
            – Jimmy
            Nov 12 '18 at 22:19














          • 3




            The separation of 982ft would also most likely not be "out of bounds" for the 1000ft rule, since ATC scopes only see increments of 100ft. Per the ATC data, the two aircraft were back into the 5+ horizontal separation range before they fell out of the 1000ft vertical separation range.
            – Jimmy
            Nov 12 '18 at 22:19








          3




          3




          The separation of 982ft would also most likely not be "out of bounds" for the 1000ft rule, since ATC scopes only see increments of 100ft. Per the ATC data, the two aircraft were back into the 5+ horizontal separation range before they fell out of the 1000ft vertical separation range.
          – Jimmy
          Nov 12 '18 at 22:19




          The separation of 982ft would also most likely not be "out of bounds" for the 1000ft rule, since ATC scopes only see increments of 100ft. Per the ATC data, the two aircraft were back into the 5+ horizontal separation range before they fell out of the 1000ft vertical separation range.
          – Jimmy
          Nov 12 '18 at 22:19


















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