Question

Had our flights been on time, we __________ reached by now.​

Answer 1

Had our flights been on time, we would have reached by now.​

Use of Modal verb:

• If the first clause is in past perfect, the second clause should have a modal verb.
• A modal verb is used to show the prediction of an action or an event.
• As the narrator has mentioned that the flight wasn't on time that's why they were able to reach on time.