Ever wondered how much rest should one take to overcome jetlag.
ICAO uses Buleys formula to calculate days of rest to overcome jetlag.
Number of days of rest = ((T/2)+(z-4)+Cd+Ca)/10
where T = hours in transit
z= number of timezones crossed (0 if less than 4)
Cd and Ca are departure and arrival coefficients calculated from the following table. Substitute Cd and Ca with the value given in the table below based on time you left the starting place and arrived at the destination. All times are local times.
Time of day Cd Ca
0800-1157 0 4
1200-1759 1 2
1800-2159 3 0
2200-0059 4 1
0100-0759 3 3
0 is good,
1and2 fair,
3 poor,
4 bad.
I will try to calculate the rest one needs to take when someone travels from India to Western USA based on the above formula.
Assume transit time is 26 hours and you left India at 23:30 hrs so Cd is 4 (poor) and assume that you arrive at US by 12:00 the Ca is 2 (fair). Since US is -8 behind UTC and India 5:30 ahead z = 13:30. Since the formula is in days I leave of the :30 mins and make z = 13.
Now the amount of rest you should take is = ((26/2)+(13-4)+4+2)/10 which is 2.8 days.
But what happens practically is that you usually start on Saturday night from India and land in USA Sunday afternoon and Monday morning in an all important meeting you are either dozing off or keeping yourself awake with liberal doses of Caffeine.
