Praying on a plane when one is unable to stand or face the qiblah

Firstly: 

Standing and facing the qiblah during an obligatory prayer
are two of the essential parts of the prayer, without which it is not valid
unless one has an excuse. Among the excuses that the scholars have mentioned
in this regard is one who prays in an airplane and is unable to stand or
face the qiblah, if he is afraid that the time for prayer will end and the
prayer is one that cannot be joined to the prayer that comes before it or
after it. 

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was
asked about a man who was travelling by plane, and he did not know the
direction of the qiblah because no one else there knew it either. He prayed
and he did not know whether he was facing the qiblah during his prayer or
not. Is prayer in such circumstances valid?

He replied: If the traveller in a plane wants to offer a
naafil prayer, then he may pray in whatever direction he is facing and he
does not have to face the qiblah, because it is proven that the Prophet
(peace and blessings of Allaah be upon him) used to pray on his camel no
matter what direction it was facing, when he was travelling. But with regard
to obligatory prayers, it is essential to face the qiblah and to bow and
prostrate if one is able. Therefore if a person is able to pray properly
when he is in the plane, then he should do so., but if the prayer whose time
has come when he is in the plane is one which may be joined with the prayer
that comes after it, such as if the time for Zuhr, he can delay it and join
it with ‘Asr, and if the time for Maghrib comes when he is in the plane, he
can delay it and join it with ‘Isha’.  He should ask the flight attendants
about the direction of the qiblah if he is in a plane where the direction of
the qiblah is not shown. If he does not do that then his prayer is not
valid. End quote from Majallat al-Da’wah, issue no. 1757, p. 45. 

The Standing Committee was asked: If I am travelling by plane
and the time for prayer comes, is it permissible for us to pray in the plane
or not? 

They replied: If the time for prayer comes and the plane is
continuing its journey, and there is the fear that the time for prayer may
end before it lands in an airport, then the scholars are unanimously agreed
that it is obligatory to offer the prayer as best as one is able to, bowing,
prostrating and facing the qiblah if one can, because Allaah says
(interpretation of the meaning): “So keep your duty to Allaah and fear
Him as much as you can” [al-Taghaabun 64:16]. And the Prophet
(peace and blessings of Allaah be upon him) said: “When I command you to do
a thing, do as much of it as you can.” Narrated by Muslim (1337). 

But if he knows that the plane will land before the time for
the prayer ends and that he will have enough time to offer the prayer then,
or if the prayer is one that may be joined with another, such as Zuhr with
‘Asr or Maghrib with ‘Isha’, or he knows that the plane will land before the
end of the time for the second prayer and that he will have enough time to
offer both prayers, then the majority of scholars are of the view that it is
permissible to offer the prayer in the plane, because of the command to
offer the prayers on time to the best of one’s ability, as stated above, and
this is the correct view. End quote. 

Fataawa al-Lajnah al-Daa’imah
(8/120). 

They were also asked (8/126): Is it permissible to pray
sitting in the plane even though one is able to stand, because one feels
shy? 

They replied: It is not permissible to pray sitting in the
plane or elsewhere if one is able to stand, because of the general meaning
of the words of Allaah (interpretation of the meaning): “And stand before
Allaah with obedience” [al-Baqarah 2:238]. And it is narrated in
Saheeh al-Bukhaari from ‘Imraan ibn Husayn that the Prophet (peace
and blessings of Allaah be upon him) said to him: “Pray standing, and if you
cannot, then sitting, and if you cannot, then on your side.” Al-Nasaa’i
added with a saheeh isnaad: “and if you cannot then lying on your back.” End
quote.  

Secondly: 

Purification is an essential condition of prayer being valid.
You prayed with wudoo’ so your prayer is valid in sha Allaah, but it is
makrooh to pray when suppressing the urge to urinate, defecate or pass wind,
if it is strong, because that will affect one’s focus and presence of mind
when praying, but the prayer is still valid in sha Allaah. 

Based on the above, we may sum up as follows: if you did not
stand and face the qiblah because you were unable to do so, then your prayer
is valid, but if you were able to stand or face the qiblah but you did not
do so then your prayer is not valid and you have to repeat it now.  

We ask Allaah to accept your ‘umrah and to reward you with
good for your keenness to ask and find out. 

And Allaah knows best.