Can hand sanitizer be used for ablution?

You can combine prayers during travel.
and no hand sanitizer isn't ablution, anymore than you can use it to scrub in for surgery. You've to do it as prescribed..

and Allah swt knows best,

you can get or make these dust tablets - sort of like a small soap bar for tayamum and keep it in a large weed bag with your razor toothbrush etc.

format_quote Originally Posted by Darth Ultor

Another question is how Muslim pilots pray when they have to fly all over the world. Do they take turns?

the pilot usually has a co-pilot and they also use something called auto-pilot which does most of the mapped out work once the need for split second decision-making is past (eg. they're travelling at their correct hight and on their flight path).

also - you don't have to alight from your seat to pray in certain circumstances.

"Guard strictly your (habit of) prayers, especially the Middle Prayer¹⁴, and stand before Allaah devoutly. If you fear (an enemy) then pray on foot, or while riding. But when you are in security, celebrate Allaah's praises in the manner He has taught you, which you did not know before."
(Baqarah, 2:238-9)

He (pbuh) was asked about prayer on a ship, so he said, Pray on it standing, unless you are afraid of drowning.
(Bazzaar (68), Daaraqutni, `Abdul Ghani al-Maqdisi in his Sunan (82/2) and Haakim declared it saheeh and Dhahabi agreed).

As far as praying on board means of transportation is concerned, then it is possible to pray there so long as the necessary conditions of prayer are fulfilled, or else one can wait until one gets out of the vehicle. If waiting means that the time for the prayer will pass, then you should pray in the best way that you can. Let us assume, for example, that you are in a car or train where there is no place to pray, you cannot stop and pray at the side of the road, and the time for that prayer is running out. In such a situation, the Muslim should pray in the best way that he can, even if he is sitting in his seat and even if he is not facing the qiblah, 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 because the Prophet (peace and blessings of Allaah be upon him) said: "If I have commanded you to do something, do as much of it as you can." (Reported by al-Bukhaari, al-Fath, no. 7288)

An exception to be above is naafil (supererogatory) prayers offered when riding a camel, which is permissible even if one cannot get down or if one is not facing the qiblah. This is known from the report of Ibn 'Umar, who said: "The Prophet (peace and blessings of Allaah be upon him) used to pray when travelling on his camel, no matter which direction it was facing, and he would gesture with his head to indicate the movements of the night prayer, apart from the obligatory prayers, and he would pray witr on his camel too." (Reported by al-Bukhaari, 945)

Ibn 'Umar (may Allaah be pleased with him) said: "The Prophet (peace and blessings of Allaah be upon him) used to pray voluntary (nafl) prayers when riding on his camel, no matter what direction it was facing, when he came from Makkah to Madeenah." Then Ibn 'Umar recited this aayah (interpretation of the meaning): "And to Allaah belong the east and the west, so wherever you turn yourselves or your faces, there is the Face of Allaah (and He is High above, over His Throne)…" [al-Baqarah 2:115]

Ibn 'Umar said: "It was concerning this that this aayah was revealed."
(Reported by al-Tirmidhi, 2883; he said, this is a saheeh hasan hadeeth)