A: Raising the hands while offering Du`a', wherever a person may be, is one of the causes of acceptance of the Du`a', as the Prophet (peace be upon him) stated: Allah is characterized by modesty and reserve, and is ashamed to turn away His servant emptyhanded when he raises them to Him.
The Prophet (may Allah's Peace and Blessings be upon him) also says: Allah (may He be Exalted) is good and accepts only that which is good. Allah has commanded the believers to do that which He commanded the messengers.
O you who believe (in the Oneness of Allâh Islâmic Monotheism)! Eat of the lawful things that We have provided you with, and be grateful to Allâh
O (you) Messengers! Eat of the Tayyibât [all kinds of Halâl foods which Allâh has made lawful (meat of slaughtered eatable animals, milk products, fats, vegetables, fruits, etc.] and do righteous deeds.
Then he mentioned [the case of] a man who, having journeyed far, is disheveled and dusty spreading out his hands to the sky [saying] : "O Lord! O Lord!" while his food is unlawful, his drink unlawful, his clothing unlawful, and he is nourished unlawfully, so how can he be answered! (Relatedby Muslim in his Sahih 'authentic' Book of Hadith).
However, the virtue of raising hands during Du`a' applies whether a person is aboard a plane, a train, a car, a spacecraft, etc. Only in cases where the Prophet (peace be upon him) did not raise his hands in Du`a', should we do the same and not raise our hands.
One of these cases is during Khutbah (sermon) for Jumu`ah (Friday) Prayer as the Prophet (peace be upon him) did not raise his hands during this time, unless he was make Du`a' for rain. The Prophet (peace be upon him) also did not raise his hands between the two Sujuds (Prostrations) and before Taslim (salutation of peace ending the Prayer) when concluding Tashahhud (a recitation in the sitting position in the last unit of Prayer).
for the Prophet's doing of something or refraining from doing it is a proof that we must, or must not do the same. Again, we are to raise our hands in the cases which the Prophet (peace be upon him) did so following his example (peace be upon him). This is also because raising the hands during Du`a' is one of the reasons for acceptance by Allah (Exalted be He). So we should also raise hands during Du`a' in cases where there is no narration defining whether he (peace be upon him) raised his hands or not, for raising hands is a cause of acceptance.