Narrative:

I was working local control west (lcw) and local control south (lcs) combined. Aircraft were landing and departing runway 30L; and landing 35. There is a separate published frequency for each runway at msp. I cleared MD90 for takeoff on runway 30L; unknown to me the pilot was on the runway 35 tower frequency. Immediately after; we split the lcw and lcs positions. At the departure end of runway 30L; I gave a MD90 a turn to heading 260 and instructed him to contact departure. Receiving no response; I repeated the control instruction. Still no response; I assumed the pilot had changed to departure frequency on his own; a not uncommon event. I called down to the departure controller and told him the MD90 had switched frequencies on his own; and told him to turn the MD90 left to heading 260. He replied in the affirmative. Several seconds later the departure controller called up to the tower and told us to ship the MD90. I replied with I already tried; he must have switched on his own. They said they didn't have him either. At that point I yelled out for everyone in the tower to try the MD90. It was discovered at that point that he was on the incorrect tower frequency. The new lcw controller issued the MD90 to turn to a 260 heading; he did not respond. The instruction was repeated and the aircraft still did not respond; several seconds later the MD90 broad casted on lcw frequency that he was level at 7;000 flying heading 260. The closest the pilot came to another aircraft was a crj that departed after the MD90 on the parallel runway. The crj was about a mile behind the MD90 and within 500 ft. As the MD90 did not acknowledge his turn until 3-5 miles off of the departure end; he and the crj were on parallel headings until he responded to the turn. That is where the loss of separation took place. I was informed that this was an operational error; however I completely disagree with this classification. Recommendation; msp does not have signage indicating the appropriate tower frequency at the end of each runway. Up until now; the only time this has really been an issue is when we are on the 12s/17 configuration. Pilots are instructed to monitor the lcs frequency for their runway crossing; and many do not change to the lcw frequency when they get to that runway. I believe signage at the end of each runway would remedy this situation.

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Original NASA ASRS Text

Title: MSP Controller described a loss of separation when unable to turn a departure; the event occurring shortly after de-combining the Local Control positions with one departure on the wrong frequency.

Narrative: I was working Local Control West (LCW) and Local Control South (LCS) combined. Aircraft were landing and departing Runway 30L; and landing 35. There is a separate published frequency for each Runway at MSP. I cleared MD90 for takeoff on Runway 30L; unknown to me the pilot was on the Runway 35 Tower frequency. Immediately after; we split the LCW and LCS positions. At the departure end of Runway 30L; I gave a MD90 a turn to heading 260 and instructed him to contact departure. Receiving no response; I repeated the control instruction. Still no response; I assumed the pilot had changed to Departure frequency on his own; a not uncommon event. I called down to the Departure Controller and told him the MD90 had switched frequencies on his own; and told him to turn the MD90 left to heading 260. He replied in the affirmative. Several seconds later the Departure Controller called up to the Tower and told us to ship the MD90. I replied with I already tried; he must have switched on his own. They said they didn't have him either. At that point I yelled out for everyone in the Tower to try the MD90. It was discovered at that point that he was on the incorrect Tower frequency. The new LCW Controller issued the MD90 to turn to a 260 heading; he did not respond. The instruction was repeated and the aircraft still did not respond; several seconds later the MD90 broad casted on LCW frequency that he was level at 7;000 flying heading 260. The closest the pilot came to another aircraft was a CRJ that departed after the MD90 on the parallel runway. The CRJ was about a mile behind the MD90 and within 500 FT. As the MD90 did not acknowledge his turn until 3-5 miles off of the departure end; he and the CRJ were on parallel headings until he responded to the turn. That is where the loss of separation took place. I was informed that this was an operational error; however I completely disagree with this classification. Recommendation; MSP does not have signage indicating the appropriate Tower frequency at the end of each runway. Up until now; the only time this has really been an issue is when we are on the 12s/17 configuration. Pilots are instructed to monitor the LCS frequency for their runway crossing; and many do not change to the LCW frequency when they get to that runway. I believe signage at the end of each runway would remedy this situation.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.