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Tol controller providing OJT described a possible loss of separation event involving a helicopter taxiway departure along side of an air carrier departure; noting the required separation criteria is less than clear.

Narrative:

An MD83; was cleared for take off on runway 25; about the time the MD83 was airborne a helicopter called the tower for a VFR departure to the southwest; and reported the MD83 in sight. The developmental issued the departure frequency and a squawk code. The helicopter had difficulty hearing the code and required it be read back to him twice before he got it. By this time the helicopter had hover taxied to taxiway bravo; a parallel of runway 25; and reported ready. The developmental cleared the helicopter for take off; without issuing a cautionary wake turbulence advisory; the helicopter; being ready; departed immediately prior to my being able to properly issue the wake turbulence advisory. Per the 7110.65 the ruling for this behind a large aircraft is very grey; on whether or not it's actually required or if there is a requisite delay. The time frame between the MD83 departing and the helicopter departing wasn't known at the time; after looking into it we found that the time was outside of a three minute required delay. Recommendation; the 7110.65 is vague in this situation and doesn't prescribe a ruling for situations such as this for large aircraft only heavy's. If it could be made clear whether it's allowed to depart from 'parallels' at an 'intersection' behind a larger aircraft; other than a heavy; would remove the grey area of understanding.

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Original NASA ASRS Text

Title: TOL Controller providing OJT described a possible loss of separation event involving a helicopter taxiway departure along side of an Air Carrier departure; noting the required separation criteria is less than clear.

Narrative: An MD83; was cleared for take off on Runway 25; about the time the MD83 was airborne a helicopter called the Tower for a VFR departure to the southwest; and reported the MD83 in sight. The developmental issued the departure frequency and a squawk code. The helicopter had difficulty hearing the code and required it be read back to him twice before he got it. By this time the helicopter had hover taxied to Taxiway Bravo; a parallel of Runway 25; and reported ready. The developmental cleared the helicopter for take off; without issuing a cautionary wake turbulence advisory; the helicopter; being ready; departed immediately prior to my being able to properly issue the wake turbulence advisory. Per the 7110.65 the ruling for this behind a large aircraft is very grey; on whether or not it's actually required or if there is a requisite delay. The time frame between the MD83 departing and the helicopter departing wasn't known at the time; after looking into it we found that the time was outside of a three minute required delay. Recommendation; the 7110.65 is vague in this situation and doesn't prescribe a ruling for situations such as this for Large aircraft only heavy's. If it could be made clear whether it's allowed to depart from 'parallels' at an 'intersection' behind a larger aircraft; other than a heavy; would remove the grey area of understanding.

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.