Narrative:

Aircraft X; a recat category D aircraft; departed runway 9R. The controller in charge-it I was instructing departed aircraft Y; a recat category F aircraft; behind aircraft X without waiting for the required 4 mile wake turbulence distance. I did not notice the error until aircraft Y was lifting off; because I allowed myself to be distracted trying to coordinate a release on another aircraft.I do not have a recommendation to prevent this type of event. I simply did not pay attention as closely as I should have; possibly because I made an assumption about what the person in training was going to do and the assumption did not meet the action.I would like clarification about the recat rule. This same operation would not have been an error if it had occurred at an airport that does not use recat. I fail to understand how these two conflicting standards can be allowed to coexist in the NAS. If departing a [corporate jet] too close behind an [air carrier] is deemed unsafe at one airport; how can it be considered safe at another? I also believe having these two standards coexisting is confusing and dangerous to the pilots. If there were one standard throughout the NAS; and the pilots were aware of it; then they might correct an error like this by inquiring if the distance is acceptable. With two standards in play; a pilot would possibly think; 'this must be an airport where this wake turbulence distance is acceptable'. It is not really possible for the pilots to memorize which airports apply recat and which do not. If 6000 ft and airborne between these two planes is considered safe at most airports; it should be considered safe at all of them.

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Original NASA ASRS Text

Title: ORD Tower Controller reported of a loss of separation that was caused by the Developmental Controller releasing the aircraft with less than standard separation. Reporter questioned RECAT wake turbulence.

Narrative: Aircraft X; a RECAT Category D aircraft; departed RWY 9R. The CIC-IT I was instructing departed Aircraft Y; a RECAT Category F aircraft; behind Aircraft X without waiting for the required 4 mile wake turbulence distance. I did not notice the error until Aircraft Y was lifting off; because I allowed myself to be distracted trying to coordinate a release on another aircraft.I do not have a recommendation to prevent this type of event. I simply did not pay attention as closely as I should have; possibly because I made an assumption about what the person in training was going to do and the assumption did not meet the action.I would like clarification about the RECAT rule. This same operation would not have been an error if it had occurred at an airport that does not use RECAT. I fail to understand how these two conflicting standards can be allowed to coexist in the NAS. If departing a [corporate jet] too close behind an [air carrier] is deemed unsafe at one airport; how can it be considered safe at another? I also believe having these two standards coexisting is confusing and dangerous to the pilots. If there were one standard throughout the NAS; and the pilots were aware of it; then they might correct an error like this by inquiring if the distance is acceptable. With two standards in play; a pilot would possibly think; 'This must be an airport where this wake turbulence distance is acceptable'. It is not really possible for the pilots to memorize which airports apply RECAT and which do not. If 6000 ft and airborne between these two planes is considered safe at most airports; it should be considered safe at all of them.

Data retrieved from NASA's ASRS site 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.