Shouldn't American Airlines flight AA587 have been much higher than the Japan Airlines Boeing 747 and its wake (Flight International, 27 November - 3 December)?
Granted that flight AA587 flew a shorter path, still, a twin-engined aircraft leaving on a shorter flight to Santo Domingo should climb much faster than a four-engined aircraft on a long flight to Tokyo. Was flight AA587 observing some noise abatement procedure, was the crew being kind to its engines, or was it flying fast rather than climbing fast?
The last possibility got me thinking about wake encounters. If an encounter is so brief that it leaves the aircraft with changed velocity but not position - for example, with a rate of roll but no bank angle - the resulting velocity is proportional to the aircraft's airspeed. To be kind to the aircraft, go slow.
But the passive aerodynamic damping of the said velocity is inversely proportional to airspeed, and the control power available - for a given control deflection - to enable the pilot to stop the roll, is inversely proportional to the square of the airspeed. So to reduce the severity of a wake-induced upset, go fast.
The A300-600's fin deflection is supposed to be limited at the speed which it was going. Was the limiter working?
At airports with adequately spaced, parallel runways, parallel runways paired take-offs and paired landings would double capacity.
Charles McCutchen
Bethesda, USA
Source: Flight International
