A-380 Wake Vortex
ATC Might Need Increased Awareness
On January 7, 2017, a Challenger 604 and an A-380 were flying in the same airspace over the Arabian Sea.
The 38,000 pound Challenger was at 34,000’ headed to Abu Dhabi. Suddenly, the plane, out of control, experienced “significant loss of altitude, abnormal flight attitudes and accelerations beyond the certificated flight envelope.” It was determined that the plane may have lost as much as 10,000’ and rolled several times. The pilots were able to shut down one engine because its instruments registered “high inter turbine temperature.” Fortunately, the 2nd engine did not suffer the same level of damage.
The accident investigation team reviewed the ATC records and saw that an A-380 (862,000#) was nearby. Their preliminary recommendation was that ATC needs to provide LATERAL SEPARATION between the A-380 and smaller aircraft.
Super Heavy Aircraft is a standard Air Traffic Control term, which alerts pilots and others on the ATC communications frequency that the plane so designated requires additional separation. The A-380 is a super heavy.
A purpose of aircraft wings is to create lift. As the air flows over the wing, horizontal, tornado-like vortices are a product of this aerodynamic function. The trailing circulating vortices are hazards for aircraft next in the departure/arrival patterns. This dangerous, invisible, powerful, high-velocity airflow may remain in the air for a long time and cannot be seen by pilots.
This insidious phenomenon can cause extreme excursions in rolling motion, rate of climb, or even structural load factors may be experienced during an encounter with the wake. To add to the threat identified by Flight Service Bureau, the impact of a vortex is influenced by these factors (NASA):
- “the size, geometry, and operating conditions of the generating and trailing aircraft;
- the distance between the two aircraft;
- the angle and altitude of the encounter;
- merging, and decay of the vortices;
- and local atmospheric conditions that influence the position, strength.”
- “As Aircrew, use SLOP whenever you can.
- As Controllers, be mindful of smaller aircraft passing underneath A380’s.
- Avoid flying the centreline if you can. SLOP 0 is not an offset. Choose 1nm or 2nm.
- Note the new SLOP rules from ICAO in the 16th edition of Doc 4444.
- Expect guidance from EASA and the FAA to follow
- with very recent updates to both NAT Doc 007 and ICAO Doc 4444, the rules for SLOP are a little different than before.”
NextGen and SESAR both allow aircraft to fly closer in trail; because the greater precision of these system. The as-of-yet incomplete analysis of this January Challenger 604 and an A-380 may require increased vigilance by ATC of the A-380 wake vortices.