Close calls at Denver International Airport

What's up with these close calls at DIA?

A month ago we had this tale of a runway incursion at DIA:

Frontier Airlines flight 297, an Airbus A-319, broke out of low clouds as it was about to land on runway 35 left. The Frontier flight crew saw a Swearingen Metroliner, Key Lime Air flight 4216, which had inadvertently entered the runway. The Frontier flight immediately executed a missed approach. It is estimated that the aircraft came within 50 feet of each other.

The Airport Movement Area Safety System (AMASS) alerted the control tower personnel of the situation at the same time the Frontier crew saw the Metroliner on the runway. Weather at the time of the incident was one-half mile visibility, ceiling 600 feet overcast, snow and mist.[NTSB News, Jan. 5, 2007]

Then last Friday -- same airport, different month -- it was a case of "déjà vu all over again:"

A United Airlines Boeing 737, operating as flight 1193 from Billings, Montana, landed on runway 26 at Denver International Airport (DEN). One of the pilots noticed a snowplow on the runway and the crew used maximum braking power and full use of the thrust reversers to bring the aircraft to a complete stop. The plane missed the snowplow by about 200 feet. There were no injuries to the 101 persons aboard or the operator of the snowplow.

The plow was being escorted by an airport operations vehicle that was in radio communications with the air traffic control tower, but the vehicles had become separated, with the escort vehicle already having cleared the runway. It is unclear if the snowplow was in radio communications with either the escort vehicle or the tower. Visibility at the time of the incident was about 10 miles. [NTSB News, Feb. 5, 2007]

It's been a trying season for DIA -- blizzards, runway incursions, what next? I know, don't ask!

An article about the snowplow incident that appeared on Colorado's Summit Daily News website quoted Turner West, aviation manager at Denver International, who said that the airport is working with the NTSB and the Federal Aviation Administration to determine what happened. West said the airport is also conducting its own investigation and has put more training in place for plow drivers.

Should we view that as a step in the right direction, or as a case of closing the barn door after the horse got out?

In any case, kudos to those Frontier and United pilots who so skillfully avoided having these incidents end up as accidents!