Delta Air Lines (NYSE:DAL) saw a modest slump in most of its passenger metrics last month. For February, total revenue passenger miles -- a key metric measuring the total distance traveled by paying customers -- declined by just over 2% on a year-over-year basis to hit 12.7 billion.

Meanwhile, available seat miles -- the calculation of the total number of miles available for a carrier to sell -- declined by 5% over that same stretch of time to land a bit above 16 billion.

In terms of what was carried on its aircraft, Delta reported that the number of boarded passengers fell to 11.1 million, a drop of almost 3% from Feb. 2012's figure. Cargo ton miles declined 3.5% on an annual basis, coming in at 179 million.