AIM ¶ 7-4-9 — ATC Wake Turbulence Separation

7-4-9. 7-4-9. Air Traffic Wake Turbulence Separations Because of the possible effects of wake turbulence, controllers are required to apply no less than minimum required separation to all aircraft operating behind a Super or Heavy, and to Small aircraft operating behind a B757, when aircraft are IFR; VFR and receiving Class B, Class C, or TRSA airspace services; or VFR and being radar sequenced. Typical separation applied to aircraft operating directly behind a super or heavy at the same altitude or less than 1,000 feet below, and to small aircraft operating directly behind a B757 at the same altitude or less than 500 feet below: Heavy behind super - 5 miles. Large behind super - 7 miles. Small behind super - 8 miles. Heavy behind heavy -3 miles. Small/large behind heavy - 5 miles. Small behind B757 - 4 miles. Also, separation, measured at the time the preceding aircraft is over the landing threshold, is provided to small aircraft: Small landing behind heavy - 6 miles. Small landing behind large, non-B757 - 4 miles. REFERENCE- Pilot/Controller Glossary Term- Aircraft Classes. Additionally, appropriate time or distance intervals are provided to departing aircraft when the departure will be from the same threshold, a parallel runway separated by less than 2,500 feet with less than 500 feet threshold stagger, or on a crossing runway and projected flight paths will cross: Three minutes or the appropriate radar separation when takeoff will be behind a super aircraft; Two minutes or the appropriate radar separation when takeoff will be behind a heavy aircraft. Two minutes or the appropriate radar separation when a small aircraft will takeoff behind a B757. NOTE- Controllers may not reduce or waive these intervals. A 3-minute interval will be provided when a small aircraft will takeoff: From an intersection on the same runway (same or opposite direction) behind a departing large aircraft (except B757), or In the opposite direction on the same runway behind a large aircraft (except B757) takeoff or low/missed approach. NOTE- This 3-minute interval may be waived upon specific pilot request. A 3-minute interval will be provided when a small aircraft will takeoff: From an intersection on the same runway (same or opposite direction) behind a departing B757, or In the opposite direction on the same runway behind a B757 takeoff or low/missed approach. NOTE- This 3-minute interval may not be waived. A 4-minute interval will be provided for all aircraft taking off behind a super aircraft, and a 3-minute interval will be provided for all aircraft taking off behind a heavy aircraft when the operations are as described in subparagraphs c 1 and c 2 above, and are conducted on either the same runway or parallel runways separated by less than 2,500 feet. Controllers may not reduce or waive this interval. Pilots may request additional separation (i.e., 2 minutes instead of 4 or 5 miles) for wake turbulence avoidance. This request should be made as soon as practical on ground control and at least before taxiing onto the runway. NOTE- 14 CFR section 91.3(a) states: “The pilot-in-command of an aircraft is directly responsible for and is the final authority as to the operation of that aircraft.” Controllers may anticipate separation and need not withhold a takeoff clearance for an aircraft departing behind a large, heavy, or super aircraft if there is reasonable assurance the required separation will exist when the departing aircraft starts takeoff roll. Previous | Top | Next AIM | ATPUBS | FAA | Send your comments regarding this website.