Widebody; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 5
Distraction; Situational Awareness; Confusion
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Wake Vortex Encounter
Air Traffic Control Provided Assistance
Human Factors; Procedure
I was working the West Jet Departure position; sitting beside the CPC-IT working the East Jet Departure position; when I observed this scenario play out. Aircraft X departs on a tower assigned heading of 040-degrees; routed on the MOONNx SID; climbing to 10;000-ft. No issue; controller radar identifies him and he continues climbing on the tower-assigned heading until a prescribed LOA altitude at which the radar departure controller has control for turns in the tower's delegated departure dispersal area. Next; Aircraft Y departs on the same 040-degree tower-assigned heading; routed on the ERRTHx SID; climbing to 10;000-ft also. Everything is fine; except for the fact that Aircraft Y tags up on radar around 4.7x miles in-trail of Aircraft X; and closing that distance rapidly. Naturally; Aircraft Y in a busy airline hub environment; is going to accelerate as quickly as operationally feasible to maintain 250-knots in order to expedite traffic flows and get up and out as quickly as possible. In a mixed-fleet environment of large wake class airline aircraft (Boeing; Airbus; Embraer; Bombardier; Canadair; etc.); this is a consistent performance expectation bias and everything runs smoothly. But Aircraft X's [Company] and other foreign heavy operators that fly [Heavy] aircraft into and out of DTW; have a recurring tendency to brief and fully plan in the cockpit to execute a high-performance departure climb maneuver; common outside the United States. In noise-sensitive regions like Europe; the Middle East; and Asia; these heavy aircraft are instructed/mandated to climb out at maximum deck angle for aircraft capabilities in order to gain as much altitude as possible in as short a distance as possible; or maximum climb gradient. The negative penalty of this maneuver is that forward groundspeed suffers; to the detriment of showing 160-180 knots groundspeed; while the next departure hits positive rate; gear up; and accelerates immediately to 250 knots indicated airspeed. Aside from habit or familiarity; the justifiable reason that this particular Aircraft X crew executed this maneuver is because of an arbitrary crossing restriction published on all of the SIDs off of DTW; mandating to cross 10-DME at/above 5;000-ft MSL. Meanwhile; the SIDs have no speed published aside from a requirement to maintain 280-knots above 10;000-ft MSL. Below 10;000-ft; they could feasibly do whatever speed they like; so technically; the Aircraft X crew did nothing wrong and had every right to do what they did; nor do they have any regulatory requirement to inform or advise ATC of intentions to execute a maximum climb gradient takeoff procedure. The loss of standard IFR separation and the corresponding wake remnant/turbulence encounter is the fault of the DTW Metro Tower controllers for not recognizing the airline; aircraft type; and ATC intention to launch Aircraft Y with minimum wake turbulence runway separation of 2 minutes along the same route of flight.DTW is a hub. Even back in the day; Heavy B747-400 aircraft had an arrangement with the DTW Tower whereby they would advise their inability to comply with the 10-DME 5;000-ft crossing restriction due to weight and aircraft performance for their trans-Pacific flights to Asia and trans-Atlantic flights to Europe; and the Tower would advise the flight crew not only to disregard the crossing restriction; but also permit them to increase speed to 280-knots off the runway. Vertical climb performance was pitiful; to say the least; but their groundspeed was sufficient to keep traffic moving off the airport environment without the heavy becoming an impediment or nuisance. This practice continues even today; but seems to only apply to the [Company] -branded aircraft. Other operators utilize Heavy aircraft at DTW; but they don't seem to benefit from that same exception or best practice that's been established for years. So when they recognize how heavy their takeoff weight is; and they see this arbitrary crossing restriction published on the SIDs; they brief to fly their aircraft in such a manner as to comply to the best of their ability with the procedure that their dispatchers filed for them to fly; trusting that their Company would not have filed for them to fly a procedure that the aircraft would not be capable of meeting the restrictions of. It seems as though there are two possible solutions to this ongoing problem: either Local controllers in the Tower should wait an extra 30-60 seconds beyond the bare minimum 2:00 for wake turbulence separation prior to launching any other aircraft in-trail of one of these participants; and allow them to continue operating their aircraft in the manner that they do now; or there should be a productive and effective outreach effort put into place in order to educate the dispatchers and flight crews of these airlines and aircraft types that there is another option; that ATC here locally would likely rather waive the crossing restriction in exchange for faster ground speeds on departure; and that 280-knots is even available below 10;000-ft MSL should they need it for weight or aircraft performance enhancement. Otherwise; the status quo will continue on; whereby TRACON controllers bring this trend to the attention of Tower controllers; who defend themselves and argue that they provided their required 2:00 wake turbulence separation and did nothing wrong or illegal; and the fact that it results in a radar loss of separation plus a drastic overtake separation involving a wake turbulence encounter is the TRACON's problem and not theirs. I'm sick and tired of this becoming a finger-pointing blame game that never results in real tangible change. Wake turbulence encounters or separation standards or controller awareness; in some fashion; has been in the FAA's 'Top 5' for a few consecutive years now; and always shows its face in recurrent training and quarterly refresher training; year after year; and I fear the day that a 50-seat CRJ/ERJ or a small corporate jet departs in-trail of a Heavy departing DTW for Asia/Europe and gets flipped upside-down by wake vortices less than 5 miles off the departure end of DTW because of neglect and/or ignorance.
Local west departed Aircraft X on a 040 heading. I (Local East) needed 5 miles in trail of the Aircraft X and I only had somewhere more than 4 but less than 5. I waited 2 minutes before clearing Aircraft Y in trail of Aircraft X and still didn't have the necessary 5 mile separation. Aircraft X was an incredibly slow climber. I didn't take into account the trend of [long haul] heavy aircraft will climb out much slower than normal.Take even more time before any heavy aircraft. Especially a [long haul] carrier as they climb out even slower.
D21 TRACON and DTW Tower Controllers reported a loss of separation due to different climb rates on two departures.