AirxLiban, the AN
-140 is not an old plane but a brand new aircraft type !
It is the "equivalent" of the ATR-42, the main difference between the two a/c being the tail design :
a route like BEY-LCA is operated by MEA
with A321 or sometimes A332 but with a frequency of 1 x Daily...
wants to make of BEY a powerful hub, they must attract the PAX from the region by offering a lot of frequencies (especially on the short routes) and a minimum transit time at BEY. The "ATR type" regional a/c are just perfect for this "commuter" mission.
Moreover, BEY-LCA is very popular among Lebanese and flights always full. The distance is only 200km (129mi).
BEY-DAM is 105km (65mi), BEY-AMM is 237km (147mi), DAM-AMM is 194km (120mi)
Actually, BEY-AMM (already flown by MEA
's A321) is a bit longer as a/c are not allowed to fly straight over the occupied Palestine.