AA parked 5 of 9 fleet types.

MD80 (parked shortly before COVID-19)
E190
B757
B767
A330

These amounted to about 10% of the fleet.

In all the COVID-19 impacts, the fleet simplification to two narrow body and two wide body series is often missed.

Standardization of parts, mechanics training, and pilot training should not be underestimated to the operations or the bottom line. This will be a positive impact long after COVID-19 is just a faint memory.