ETP (equal time point)
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Equal Time Point (ETP) = Total Ground distance *(GSr/(GSr + GSc))
Total Ground Distance = ground distance along intended route
GSr = Ground speed return
GSc = Ground speed continue
The ground speed is the average TAS plus the wind. With the wind sign convention as headwind -ve and tailwind +ve
Total Ground Distance = ground distance along intended route
GSr = Ground speed return
GSc = Ground speed continue
The ground speed is the average TAS plus the wind. With the wind sign convention as headwind -ve and tailwind +ve
Last edited by Engineer; 21st Sep 2007 at 14:31.
Join Date: Feb 2007
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Its also called PET - point of equal time
d = (D * H)/ (O + H)
d= dist to pet from A , D =total dist between the two bases,
H= GS home from PET to A , O= GS on from PET to B
Hope it helps .. further info available from Ground Studies for Pilots
d = (D * H)/ (O + H)
d= dist to pet from A , D =total dist between the two bases,
H= GS home from PET to A , O= GS on from PET to B
Hope it helps .. further info available from Ground Studies for Pilots
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ETP = (D x GSret)/(GSret + GSFWD)
D = total distance for flight
GSret = ground speed from the ETP back to the orgin
GSfwd = ground speed from the ETP to the destination
ETP = distance from the departure airport to the ETP
Don't forget your wind shift and wet footprint.
Thank goodness todays computer generated flight plans(CFP) caculate all this for you. They also calculate for the senario of an engine loss, which would produce a driftdown to a lower altitude, with different fuel burns at same and lower speeds.
D = total distance for flight
GSret = ground speed from the ETP back to the orgin
GSfwd = ground speed from the ETP to the destination
ETP = distance from the departure airport to the ETP
Don't forget your wind shift and wet footprint.
Thank goodness todays computer generated flight plans(CFP) caculate all this for you. They also calculate for the senario of an engine loss, which would produce a driftdown to a lower altitude, with different fuel burns at same and lower speeds.
