3 ms·

At what distance a flight would you use a great circle route? How is a continuous compass heading derived for a GC? Example, San Francisco US, SFO (37°37'08"N

by adolph 4y ago

At what distance a flight would you use a great circle route? How is a continuous compass heading derived for a GC? Example, San Francisco US, SFO (37°37'08"N 122°22'31"W), to Granada Spain, GRX (37°11'19"N 3°46'38"W) would go north of Newfoundland Canada: http://www.gcmap.com/mapui?P=SFO-GRX%0D%0A&MS=wls&DU=mi http://www.gcmap.com/mapui?P=SFO-GRX%0D%0A&MS=wls&DU=mi

kortilla 4y ago
The first non-stop flights to Hawaii from mainland US were part of a competition put on by Dole leaving from Oakland. The 1st place plane took off after the 2nd place plane. This happened because the navigator of the 2nd place flight didn’t take into account the great circle distance and flew straight headings.
- captaincrowbar 4y ago
  "The first non-stop flights to Hawaii from mainland US" (looks at map of Pacific) Hang on ... where did the earlier ones stop?
  - kqr 4y ago
    On... boats? Not sure.
  - Akronymus 4y ago
    I assume non-stop means direct, in this case.
  - kortilla 4y ago
    In the water: https://airandspace.si.edu/exhibitions/hawaii-by-air/online/early-flights/crossing-the-pacific.cfm https://airandspace.si.edu/exhibitions/hawaii-by-air/online/...
drpixie 4y ago
In practice, there's not a specific distance but planning convenience. For short manually planned tracks (eg VFR planning), most people will plan from one visually helpful waypoint to another, and measure the heading at the mid-point of each route segment. The midpoint approximates the GC heading, and anyway the discrepancy is (very) small on short segments. For long tracks (eg IFR interstate or intercontinental flights), most plans comply with standard routes, between nominal waypoints, and the route segments together may approximate GC tracks. Between each waypoint, one normally flies a constant heading. This is imperfect, but variations due wind and traffic are far bigger than losses due not quite conforming to a GC track.
bonzini 4y ago
Madrid-Los Angeles indeed goes all the way north of Newfoundland, even northern than the great circle. The exact route taken over the Atlantic may vary from day to day depending on weather conditions. https://www.flightradar24.com/data/flights/ib6171#2ebdae12 https://www.flightradar24.com/data/flights/ib6171#2ebdae12

by adolph 4y ago

kortilla 4y ago

The first non-stop flights to Hawaii from mainland US were part of a competition put on by Dole leaving from Oakland. The 1st place plane took off after the 2nd place plane. This happened because the navigator of the 2nd place flight didn’t take into account the great circle distance and flew straight headings.

captaincrowbar 4y ago
"The first non-stop flights to Hawaii from mainland US" (looks at map of Pacific) Hang on ... where did the earlier ones stop?
- kqr 4y ago
  On... boats? Not sure.
- Akronymus 4y ago
  I assume non-stop means direct, in this case.
- kortilla 4y ago
  In the water: https://airandspace.si.edu/exhibitions/hawaii-by-air/online/early-flights/crossing-the-pacific.cfm https://airandspace.si.edu/exhibitions/hawaii-by-air/online/...

drpixie 4y ago

In practice, there's not a specific distance but planning convenience. For short manually planned tracks (eg VFR planning), most people will plan from one visually helpful waypoint to another, and measure the heading at the mid-point of each route segment. The midpoint approximates the GC heading, and anyway the discrepancy is (very) small on short segments. For long tracks (eg IFR interstate or intercontinental flights), most plans comply with standard routes, between nominal waypoints, and the route segments together may approximate GC tracks. Between each waypoint, one normally flies a constant heading. This is imperfect, but variations due wind and traffic are far bigger than losses due not quite conforming to a GC track.

bonzini 4y ago

Madrid-Los Angeles indeed goes all the way north of Newfoundland, even northern than the great circle. The exact route taken over the Atlantic may vary from day to day depending on weather conditions. https://www.flightradar24.com/data/flights/ib6171#2ebdae12 https://www.flightradar24.com/data/flights/ib6171#2ebdae12