(F 174) I know that reciting Al-Fatiha by the follower (Ma’mum) has various rulings, and I have chosen and am inclined towards the view that says: “the Imam’s recitation waives the obligation (Rukn) of reciting Al-Fatiha for the Ma’mum.” However, what should the Ma’mum do in the following scenarios: 1- If the Ma’mum catches up with the Imam after the Imam has finished reciting Al-Fatiha in the loud prayers and the Imam is reciting another Surah. 2- What should the Ma’mum do in the case (1) if the Ma’mum attempted to recite Al-Fatiha but the Imam went into Rukoo (bowing) before the Ma’mum completed the recitation, and the Ma’mum fears that the Imam will rise from the bowing before the Ma’mum finishes reciting Al-Fatiha? – International Institute of Islamic Studies

(F 174) I know that reciting Al-Fatiha by the follower (Ma’mum) has various rulings, and I have chosen and am inclined towards the view that says: “the Imam’s recitation waives the obligation (Rukn) of reciting Al-Fatiha for the Ma’mum.” However, what should the Ma’mum do in the following scenarios: 1- If the Ma’mum catches up with the Imam after the Imam has finished reciting Al-Fatiha in the loud prayers and the Imam is reciting another Surah. 2- What should the Ma’mum do in the case (1) if the Ma’mum attempted to recite Al-Fatiha but the Imam went into Rukoo (bowing) before the Ma’mum completed the recitation, and the Ma’mum fears that the Imam will rise from the bowing before the Ma’mum finishes reciting Al-Fatiha?

Firstly, it is not obligatory for the follower (Ma’mum) to recite behind the Imam according to our school of thought under any circumstances.
Secondly, if the situation is as you described, it is preferable for you to listen to the Surah being recited by the Imam rather than reciting by yourself when you catch up with the Imam while he is reciting. However, if you have already started reciting and the Imam goes into the Rukoo (bowing), it is better for you to continue following him rather than completing the recitation of Al-Fatiha, because following the Imam is obligatory while personal recitation is recommended. Therefore, what is stronger takes precedence over what is weaker.
And Allah knows best.
Fatwa by Dr. Khālid Naṣr