On August 30, 1971 he attempted to pilot a T-33 trainer from Karachi, Pakistan to India in order to defect from the Pakistan Air Force and join the liberation movement of Bangladesh. He didn't make it though, as the other pilot in the plane forced it to crash.
For this attempt, he was awarded the Bir Sreshtho by Bangladesh which is the highest honor given. The Bangladesh Air Force's Air Base at Jessore is also named at him. This same base is home to the air force academy of Bangladesh.
Interestingly though, Rahman is viewed in a negative light in Pakistan. This is due to the fact that he tried to defect, but more importantly because the pilot who flew with him, Rashid Minhas is viewed as a hero in Pakistan. Minhas is given almost parallel treatment in Pakistan and was awarded that nation's highest award the Nishan-E-Haider and also has an air base named for him. Official accounts of Minhas' actions in Pakistan never include the name of Rahman. And likewise, official accounts of Rahman's actions do not include the name of Minhas in Bangladesh