Traffic on Hawaiian Airlines rose 5 percent in September but there were more empty seats as capacity outstripped traffic growth.

Passengers flew about 837.2 million miles, up 19.4 percent from 701.1 million miles in the prior-year period.

But capacity increased 21.6 percent to 994.6 million available seat miles from 818.2 million available seat miles.

A seat mile is one seat flying one mile. Airlines increase capacity by adding flights, using bigger planes or flying longer distances.

Average occupancy fell to 84.2 percent from 85.7 percent in September.

For the year to date, traffic climbed 2.9 percent, capacity increased 19.3 percent and average occupancy declined to 84.4 percent from 85.4 percent.

Hawaiian Airlines is a division of Hawaiian Holdings Inc. Shares of Hawaiian Holdings added 5 cents to $4.10 in afternoon trading.