What is the ruling concerning someone who travels by plane for long distances (in Ramadan); should he fast or should he break the fast and make up for it later on?

All perfect praise be to Allah, The Lord of the Worlds. I testify that none is worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

Please be informed that Allah, the Almighty, has linked the permissibility of breaking one's fast in Ramadan to two excuses; sickness or travelling. Allah Says (what means): {…So whoever among you is ill or on a journey [during them]—then an equal number of days [are to be made up].}[Quran 2: 184] Obvious as it is, the verse does not distinguish between on-foot and riding travelers, even though hardship may vary in both cases. It also goes without saying that traveling on foot is much harder than traveling using a ride. Similarly, hardship varies according to the means of transport a traveler uses. For example, a horse riding traveler does not go through the same hardship as he who rides a camel. Also, traveling by car is less hard than travelling by horse, and traveling by plane is less hard than traveling by car.      

Of course, Allah, the Almighty, knew that all means of transports that we have these days would be available. This fact is expressed in the verse where Allah enumerates the blessings that he bestowed upon people with regard to their riding mounts. He addressed the Prophet, sallallaahu ‘alayhi wa sallam, and people of his time by saying (what means): {And [Allah created] the horses, mules and donkeys for you to ride and [as] adornment. And He creates that which you do not know.}[Quran 16: 8]

According to this verse, Allah, the Almighty, explained that, later on, He would create other means of transport that would be different from those told in the verse and which people who lived in the time when revelation descended did not know by then. This includes, and Allah Knows best, the airplanes and cars that we see now.

Having known this, you should also know that Muslim scholars have stated that the cause behind permitting fast-breaking and prayer-shortening while traveling is that traveling is likely to involve hardship. Scholars have also stated that rulings that depend on probable causes do not change according to the absence or presence of such probabilities.  Accordingly, the fact that the journey by plane does not involve hardship does not prevent the traveler to use the concession. In other words, if the Muslim travels by plane he has the choice to fast or not to fast, just as other travelers who use other means of transportation. 

Hamzah ibn ‘Amr Al-Aslami narrated that he said:

“O Messenger of Allah! I feel I am able to fast while travelling. So, shall I be blamed for this?” The Prophet, sallallaahu ‘alayhi wa sallam, said, “It (breaking one's fast while traveling) is a concession that one may take or leave. It is good if you fast and it would not be wrong if you do not.” [Muslim]     

Moreover, Abu Sa‘eed and Jaabir said, “We used to travel with the Prophet, sallallaahu ‘alayhi wa sallam; some of us would fast, while others would not. However, we would not blame each other about our choices.” [Muslim]

The option of fasting while on a journey is specific to travelers who are certain that they would not go through hardship because of traveling. If a traveler believes that fasting would affect his health, then his fast can never be considered an act of righteousness. Jaabir narrated:

The Prophet, sallallaahu ‘alayhi wa sallam, was on a journey when he saw a man who was surrounded by a crowd of people who were shading him. The Prophet, sallallaahu ‘alayhi wa sallam, asked, “What is wrong with this man?” People said, “He is fasting.” The Prophet, sallallaahu ‘alayhi wa sallam, said, “It is not an act of righteousness that you fast while travelling.” [Al-Bukhari and Muslim]