The tube has an outer tube (2) and an inner tube (3) for carrying air and a cable channel outer tube (4) mounted on the outer tube. A telescopic cable inner tube inside the outer cable tube is mounted on the inner tube and contains an electrically conducting cable. A locking device (7,8) releases or prevents telescopic movement of the inner and outer tubes. The inner tube (3) is enclosed over its entire length by a further outer tube (6) which carries the inner tube and locking device and which encloses the first outer tube over some of its length. The telescopic cable channel tubes are arranged outside the air flow cross-section of the inner tube but inside both outer tubes.
