clad /kld/ verb to protect by covering
. Alloys can be protected from corro-sion by cladding the exposed surface with a thin layer of aluminium.

clamshell door /klm.el d./ noun
the hinged part of a thrust reverser .
Clamshell doors are hydraulically or pneumatically opened, and direct the exhaust gases forwards to produce reverse thrust.
classification /kls.f.ke..(.)n/
noun the act of putting things into groups or classes because they possess particular common features . Classifi-cation of aircraft consists of a multi-level diagram with each category divided into sub-categories. . A full

45 climatic zone
classification of layer cloud is given in the table.
classify /kls.fa./ verb to group items so that those with similar charac-teristics are in the same group . Precip-itation is classified as light, moderate or heavy according to its rate of fall. . The weather associated with visibility reductions by particles suspended in the atmosphere is classified either as fog, mist, haze, or smoke.
clear /kl../ adjective 1. referring to conditions in which it is easy to see, e.g. with no cloud or fog . a clear sky a sky with no cloud . a clear winter night a night with no fog, mist or other condi-tions which might impair visibility 2. possible to easily see through 3. with nothing blocking the way . clear run-way, the runway is clear nothing is on the runway . keep the exits clear do not put anything and do not stand in front of the exits 4. away from 5. easy to hear . clear of cloud either above or below cloud . keep clear (of) keep away (from) 6. easy to understand . The explanation is very clear. 7. understood
8. understood . is it clear? do you understand? . verb 1. to remove a blockage or some other unwanted effect which prevents a system from working correctly . A heater element is fitted to clear the detector of ice. 2. to disappear
. In winter frost and fog are slow to clear. 3. to make sure that it is all right to do something . clear it with the CFI make sure that the CFI agrees with the request 4. to officially ask people to quickly leave a given area or place . to clear the building to quickly leave the building
‘…the principles of weight and balance should have been learned by all pilots during their initial training, but it is clear that, afterwards, some forget’ [Civil Aviation Authority, General Aviation Safety Sense Leaflet]
COMMENT: On 27th March 1977 two Boeing 747s collided on the runway at Los Rodeos airport Tenerife in poor visibility, resulting in 575 deaths. A KLM 747 commenced take-off while a Pan Am 747 was still taxiing towards it on the same runway. There was clear-ly a breakdown in communications, perhaps a misunderstood radio call. The Pan Am aircraft had been asked by the controller, who was unable to see either aircraft due to low cloud, ‘Are you clear of the runway?’ The KLM aircraft had already commenced the take-off roll without clearance. It is possible that the KLM pilot mistook the call to the other aircraft thinking that he was ‘clear to take off’.