Delta is experiencing an abnormally high volume of flight cancellations compared to its mainline counterparts. SAUL LOEB / AFP via Getty Images

Delta canceled hundreds of flights this weekend, while American and United canceled a handful.

An internal memo obtained by Business Insider shows the reason is crew scheduling.

Delta is using a complex scheduling system to fill last-minute trips, which can be inefficient.

Delta Air Lines is canceling hundreds of flights — far more than its competitors — and its strained scheduling system is largely to blame, Business Insider has learned.

Since Friday, Delta has canceled about 500 flights, while American Airlines and United Airlines have canceled a combined total of 80 flights.…