Abu Simbel is located 280 Km South of Aswan. Till recently the only way to get there was by air. Although there is an excellent road between Abu Simbel and Aswan, for security reasons it has been closed for several years. Luckily the road had just been reopened when I visited Egypt.
In case local authorities close the road again, tourists will have to fly. Egyptair has daily flights to Abu Simbel's airport. It is important to know that while the road was closed, flight tickets were available at half its official price.
In my opinion, even though it is a long journey, it is better to travel to Abu Simbel by bus. Buses usually leave at 4 or 5 am from Aswan and come back the same day.