Index ErrorThis is the first correction we apply Index Error IE is a sextant error which we can obtain by using the sun method, as we have • Sextant Altitude : 450 25.5’ • Index Error I
Trang 2Index Error
This is the first correction we apply
Index Error (IE) is a sextant error which we can obtain by using the sun method, as we have
• Sextant Altitude : 450 25.5’
• Index Error (I.E.) : 00.2’ +
• Observed Altitude : 450 25.7’
the sun method, as we have already discovered
Applied as + or – depending on whether the IE is ‘ON’ or ‘OFF’ the arc
Assumed error = 0.2’ off
Trang 3• This correction is applied
to the ’Observed Altitude’
• It is the result of Height
of Eye
• Sextant Altitude : 450 25.5’
• Index Error (I.E.) : 00.2’ +
• Observed Altitude : 450 25.7’
of Eye
• The correction is obtained from the Nautical Almanac A2
Tables as
follows:-• Assume a HoT of
Trang 6• Dip will always be
negative
• Sextant Altitude : 450 25.5’
• Index Error (I.E.) : 00.2’ +
• Observed Altitude : 450 25.7’
• Apparent Altitude : 450 18.4’ negative
• Apparent Altitude : 45 18.4’
Trang 7Total Correction
• This is the final correction we apply
• The correction is obtained by entering the
• Sextant Altitude : 450 25.5’
• Index Error (I.E.) : 00.2’ +
• Observed Altitude : 450 25.7’
A2 / A3 Tables with Apparent Altitude
• Apparent Altitude : 450 18.4’
• Total Correction :
Trang 10Total Correction
• Sextant Altitude : 450 25.5’
• Index Error (I.E.) : 00.2’ +
• Observed Altitude : 450 25.7’
• Apparent Altitude : 450 18.4’
• Total Correction : 15.3 +
• True Altitude : 450 33.7’
Trang 11Correction for Temperature & Pressure
• Temp = 50 C
• Pressure =
1022mb