Praise be to Allaah.
The one who is travelling
by plane should pray when the time for prayer begins. In this case he can
know it by the visible signs for the times of Maghrib, ‘Isha’ and Fajr. When
the sun sets, then the time for Maghrib begins. When the red afterglow
disappears, then the time for ‘Isha’ begins. When the dawn breaks, then the
time for Fajr begins.
As for Zuhr and ‘Asr, you
can work it out. If you know their timings in the countries over which you
are flying, then you should delay the prayer for a short period and then
pray, because time in the air is not like time on the ground. And you can
join Zuhr and ‘Asr, and Maghrib and ‘Isha’, at the time of the earlier or
later prayer, depending on what is easiest for you.
You could also ask the
pilot, because he may have equipment that will enable him to work out the
times of prayer in the air.
For more information on the times of prayer – on the ground –
in most countries of the world, along with lines of latitude and longitude
and the direction of the qiblah, you can visit the website of the Ministry
for Awqaaf and Islamic affairs:
http://prayer.al-islam.com/default.asp?l=eng and print out the prayer
times for the country you are going to visit and over which you will travel
on your journey as well.
It should be noted that if a person does not know the times
but he tries to work it out as best he can, and prays, then his prayer is
valid, unless he finds out that he prayed before the time for prayer began,
in which case he should repeat it. But if he does not find out anything,
then he does not have to do anything.
And Allaah knows best.