Islam is not in reality an extremist religion. The Quran stipulates many occasions where you can fore go fasting ie when traveling, when pregnant, when sick basically whenever it is not convenient and is a threat to your life and those around you. Flying would come under this title.
Unfortunately, Muslims think that their God is unforgiving and ruthless and that they must please him in the same manner that idol worshipers must please their fire breathing gods and goddesses. The ones that believe this are the same ones that don't bother practicing their religion the rest of the year and hence have no clue that Islam is probably the most moderate of religions out of them all. The problem of course that human beings are taking it fully out of context and have become extreme and are ruining the good name in the process.
The Quran stipulates quite clearly that if you miss some days of the fast for GOOD and valid reasons then you can either make it up after Ramadan, at a time that is convenient, or you can feed the poor.
Directly from God:
شَهْرُ رَمَضَانَ الَّذِيَ أُنزِلَ فِيهِ الْقُرْآنُ هُدًى لِّلنَّاسِ وَبَيِّنَاتٍ مِّنَ الْهُدَى وَالْفُرْقَانِ فَمَن شَهِدَ مِنكُمُ الشَّهْرَ فَلْيَصُمْهُ وَمَن كَانَ مَرِيضًا أَوْ عَلَى سَفَرٍ فَعِدَّةٌ مِّنْ أَيَّامٍ أُخَرَ يُرِيدُ اللّهُ بِكُمُ الْيُسْرَ وَلاَ يُرِيدُ بِكُمُ الْعُسْرَ وَلِتُكْمِلُواْ الْعِدَّةَ وَلِتُكَبِّرُواْ اللّهَ عَلَى مَا هَدَاكُمْ وَلَعَلَّكُمْ تَشْكُرُونَ (2:185)
English Meaning:
2:185 (Asad) It was the month of ramadan in which the Qur'an was [first] bestowed from on high as a guidance unto man and a self-evident proof of that guidance, and as the standard by which to discern the true from the false. Hence, whoever of you lives to see [158] this month shall fast throughout it; but he that is ill, or on a journey, [shall fast instead for the same] number of other days. God wills that you shall have ease, and does not will you to suffer hardship; but [He desires] that you complete the number [of days required], and that you extol God for His having guided you aright, and that you render your thanks [unto Him].
Its pretty straightforward and clear, but no one bothers to read it.