また、飛行機乗るのか…

It's have been a cloudy Monday.

I'm going on a to business trip overseas tomorrow.

I'll have taken three business trips third time this year.

Alternative: "It'll be my third business trip this year."

I hate riding on aircrafts, so I feel have a melancholic now.

Alternative: "... riding on airplanes, so I'm not very pleased."
The word 'melancholy' is not often used.

It was have been cloudy on Monday.

"It's" is short for "It is" which means now. Use "was" for past tense.

I am going go to on an overseas business trip overseas tomorrow.

you can say: I will go on an overseas business trip tomorrow. or I am going on an overseas business trip tomorrow. "am going" sounds more affirmative.


put "overseas" in front of "business trip" so that it describes your subject which is business trip. add "an" when using a word that begins with a vowel.

This will be the third business trip I've I'll taken business trip third time this year.

since your last sentence was describing the business trip, you should begin your next sentence with "business trip" as your subject.

"I've" is short for "I have". Use past tense when talking about the past. You "have" taken business trips in the past and this business trip "will be the third" this year.

I hate riding ride on aircrafts, and so now I feel have a melancholy now.

you can also say "to ride on aircrafts"

but it will be more clear if you say:

"And so now, I am melancholy because I hate to ride on aircrafts."