Readers write about curbing air travel, airborne lasers, the Airbus A321XLR and Boeing 757 and Mars exploration. Plus: Behind the Scenes at Farnborough and Oshkosh.

A roundup of upcoming conferences and exhibitions.

Suppliers no longer trust Airbus and Boeing production forecasts and believe ramp-ups could be significantly delayed.

In addition to work on the Global Combat Air Program, a Boeing 757 flight-test aircraft, called Excalibur, is being adapted to trial new technology elements.