Praise be to Allah.
This question is not childish, rather it is prescribed for the intelligent person to ask questions, seek benefits and look for that which will increase his longing for Paradise and make him strive harder to reach it. Some of the Companions of the Prophet (peace and blessings of Allaah be upon him) asked him similar questions to this.
It was narrated from Sulaymaan ibn Buraydah from his father that a man asked the Prophet (peace and blessings of Allaah be upon him), “O Messenger of Allaah, are there horses in Paradise?” He said, “If Allaah admits you to Paradise, any time you wish to be carried on a horse of red rubies that will fly with you wherever you want in Paradise, you will do that.” Another man asked him, “O Messenger of Allaah, will there be camels in Paradise?” and he did not say to him something like he said to his companion. He said, “If Allaah admits you to Paradise, you will have there whatever your heart desires.”
Narrated by al-Tirmidhi, 2543; this hadeeth was classed as hasan by Shaykh al-Albaani in Saheeh al-Targheeb, 3/522.
With regard to the specific topic of your question, about a person who loves flying and airplanes, there are many saheeh ahaadeeth which speak of a similar joy.
It was proven that the souls of the martyrs are in the crops of birds in Paradise, flying wherever they wish. Narrated by Muslim, 2410.
It was proven that Ja’far ibn Abi Taalib (may Allaah be pleased with him) flies in Paradise with two wings, as an honour from Allaah and to replace his arms which were cut off in the battle of Mu’tah.
It was narrated that Abu Hurayrah said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “I saw Ja’far flying in Paradise with the angels.”
Narrated by al-Tirmidhi, 3763; classed as saheeh by al-Albaani in Saheeh al-Jaami’, 3465.
It was narrated from Ibn ‘Umar (may Allaah be pleased with him) that he used to say salaam to Ibn Ja’far and say, “Peace be upon you, O son of the one with two wings.” Narrated by al-Bukhaari, 3506.
It seems that for a person to fly by himself is more exciting for most people than flying by means of something else. There are many verses and ahaadeeth which say that people in Paradise will have whatever their hearts desire and more.
As it says in the verse (interpretation of the meaning):
“Trays of gold and cups will be passed round them; (there will be) therein all that inner-selves could desire, and all that eyes could delight in and you will abide therein forever”
Al-Sa’di said in his commentary on this verse:
“… all that inner-selves could desire…” – this phrase is comprehensive and includes every kind of blessing, joy, delight and pleasure, in the most perfect and best sense.
And Allaah says (interpretation of the meaning):
“‘Adn (Eden) Paradise (Gardens of Eternity) which they will enter, under which rivers flow, they will have therein all that they wish. Thus Allaah rewards the Muttaqoon (the pious)”
The Prophet (peace and blessings of Allaah be upon him) said: “Allaah says: ‘I have prepared for My righteous slaves that which no eye has seen, no ear has heard and it has never crossed the mind of man.’ Recite if you wish: ‘No person knows what is kept hidden for them of joy as a reward for what they used to do’ [al-Sajdah 32:17 – interpretation of the meaning].”
Narrated by al-Bukhaari, 3072; Muslim, 2824
A person should be certain of the absolute perfection of Paradise and of its people’s happiness.
With regard to being certain that there will be airplanes and airports and other things for which no proof is narrated in the texts, this is the matter of knowledge of the Unseen, which needs evidence.
We say as the Messenger (peace and blessings of Allaah be upon him) said: “If Allaah admits you to Paradise you will have therein whatever your heart desires and whatever will delight you.”
We ask Allaah to help us and you to do that which will lead us to everlasting delight in Paradise.
And Allaah knows best.