Today saw the worse air accident in the U.S. since 2001: Comair Flight 191 — a Canadair Regional Jet (CRJ) — crashed in Lexington, Kentucky. According to an NTSB official quoted in a CBC news story, the jet took off from a 3,500 ft runway. Is that OK for a fully-loaded CRJ (50 passengers and crew) under the wind and density-altitude conditions at the time? I have no idea, either of the prevailing conditions or of the CRJ’s typical takeoff roll.
Commercial flights?
What does strike me, though, is how the CBC article paraphrases the NTSB spokesperson:
The Comair commuter flight was on the shorter of two runways at Lexington’s Blue Grass airport, a 1,066-metre-long strip not supposed to be used for commercial flights, Debbie Hersmann of the National Transportation Safety Board said.
Something’s broken down in the communication chain here. Since the article paraphrases, it’s hard to know what the spokesperson actually said, but I doubt she said (or meant to say) that the runway couldn’t be used for commercial operations like air taxi, banner towing or flight training. Even if she meant to refer to scheduled air transport, wouldn’t that depend on the aircraft in use? A 3,500 ft runway would be plenty for a Piper Navajo or a DeHavilland Twin Otter flying a scheduled route, and might even meet the legal requirements for a Dash-8.
Which runway?
I’ve never been to Lexington/Blue Grass Airport (KLEX), but from reading the airport diagram, I see that the two runways are 04/22 (7,003 ft) and 08/26 (3,500 ft). The thresholds of 26 and 22 are very close to each-other — from the apron, you cross 26 (the short one) first, then almost immediately turn left onto 22. I have no idea what happened, but it’s very easy to line up on the wrong runway in a situation like this, at least for a 500 hour private pilot like me. I always have to double-check in Kingston, where runways 01 and 07 have their thresholds together, and at Toronto/City Centre, where 24 and 26 start from the same spot. My Warrior, however, has such a short takeoff roll that almost any paved runway is adequate, so my biggest risk (as long as the other runways are not in use) is being yelled at over the radio; perhaps not so with a CRJ carrying 50 souls.
Land and Hold Short 
I did listen in on that press conference and you are correct, the NTSB spokesperson did not say that commercial planes are not supposed to use that runway. I can’t recall exactly what she said, but she was extremely careful with her words to avoid saying they were using the wrong runway.
I believe what happened is one of the reporters said something like “isn’t runway 22 the runway used by commercial planes and runway 26 used by small planes?” to which she said something like “all we know is the aircraft data showed the aircraft was lined up on and departed runway 26.” I’m likely way off on the quote, but that is the gist of it.
According to data a pilot posted on a private list, the aircraft required just slightly more than the 3500′ available to reach Vr, and the balanced runway length was around 5800′. Can’t find the e-mail I’m paraphrasing.
And surely you know it isn’t a ‘commercial flight’ in the media unless it departs from a terminal equiipped with computer screens, and has jet engines, washrooms and flight attendants.