Wing Anti-ice

[Guest november678x]

Hello, I don't want to confuse this with engine anti-ice, but can wing-anti ice be turned on after start in icing conditions? I read somewhere that the valves stay closed on the ground. Does it even work on the ground? And is it even necessary when the deicing vehicles can deice you? Can someone give me the rundown on when it can or cannot be used? Thank you :-wave

[Qavion]

"...can wing-anti ice be turned on after start in icing conditions?"It depends on what you mean by "can", "November" ;-) i.e. is it operationally correct... or is it at all possible? Can't comment on the operationally correct part, but you can select the Wing Anti-Ice switch to the ON position without too many problems (the switch is not electromagnetically locked to prevent you doing this). However, air/ground relays prevent electrical power getting to the valves, so no bleed air should actually get to the wing leading edges.There is a test switch which bypasses these relays, but it is only to be used by Maintenance. If you use anti-ice for long periods on the ground on hot days, you can permanently warp the leading edge sheet metal on some aircraft. Note that the 767 has overheat safety switches which signal the valves to close at a certain high temperature value.Not all Boeings inhibit WAI on the ground... e.g the 737NG.I guess deciding (operationally or otherwise) to select the switch to ON on the ground would depend on how much faith you have in aircraft automatic safety systems ;-)Cheers.Ian.