Aerolineas Argentinas » MD-81 » Economy
On this aircraft, economy is configured 2-3 (A,B - C,D,E). If you can, grab the exit seats in row 21 or 20, although note that row 20 will not recline. Otherwise, go as far forward as possible, because the engines on the MD are attached to the fuselage at the rear, so it can be very noisy there.
