The International Civil Aviation Organisation (ICAO) has granted Boeing the use of the heavy designation for its 747-8 , continuing the wake separation rules established for the smaller 747-400.

Having examined flight test and simulation data, Boeing said ICAO has sent a letter to its member nations that the 747-8 should maintain a 9.9km (5nm) separation distance from small aircraft weighing less than 19t (41,000lbs) and those in the large category below 136t (300,000lbs). For aircraft above 136t, separation distances have been reduced to 7.4km (4nm).

ICAO "examined flight test and simulation data and established safety case arguments for approach, landing, departure, climb/descent and cruise operations of the Boeing 747-8 relative to other aircraft," the organisation's letter said.

"The safety case supports the assertion that the Boeing 747-8 is safely categorised as HEAVY. Consequently, the wake turbulence separation minima specified... for HEAVY aircraft should be applied."

By comparison, Airbus's A380, the only commercial aircraft to operate with the super designation requires an 11.1km (6nm) spacing ahead of heavy aircraft, a 13km (7nm) ahead of larger aircraft and 14.8km (8nm) ahead of small aircraft.

Boeing acquired a former Korean Air 747-400 for its flight test campaign, comparing the aircraft's wake along side a 747-8 freighter based out of San Bernardino, California.

The 747-8's larger span of 68.5m (224ft 7in) is 4.1m longer than the 747-400.

The first 747-8 freighter will be delivered to Cargolux on 19 September, and the first 747-8 Intercontinental is expected to be delivered to a VIP completion centre in early December following the completion of its flight test campaign.

Source: Air Transport Intelligence news