Sir-In your article, "Airlines force Boeing to raise 747-600X range" (Flight International, 22-28 May, P13), you mention the Airports Council International's (ACI) new report, Costs and Capacity Implications of New Large Aircraft for Airports.

I would like to clarify a point on the average capital cost per new-large-aircraft (NLA) gate modification at the airports surveyed. The article may be open to misinterpretation, because the figure of $360 million quoted is a capital cost per airport, not per gate, for the small group of three older airports in the study (those at London Heathrow, Kennedy and Los Angeles).

Our report gave an average cost per NLA gate for this group of $36 million. This compares with the average cost for all 23 airports, which replied of $105 million per airport, or $16 million per NLA gate. These figures include movement area, passenger terminal and operational costs.

The survey assumes as a baseline an "all-new" NLA aircraft of 80m wingspan and 80m length, whereas the likely Boeing 747 stretch would have a smaller wingspan and lesser length. Thus, if both these aircraft are built, the "envelope" characteristics for airport planning are likely to be similar to the 80 x 80m assumed.

ACI will continue to stay in close contact with the aircraft manufacturers and will update its conclusions accordingly.

DAVID GAMPER

Director, Facilitation and Technical Safety, Airports Council International

Geneva, Switzerland

Source: Flight International