Airliner lights

Date:         01 Mar 97 18:42:15 
From:         Jean-Francois Mezei <"[nospam]jfmezei">
Organization: SPC
Followups:    1 2 3
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It seems that on a clear day, on can see the lights from an incoming
airliner on approach that is still quite far.

I assume that those are not your everyday headlight you would put on
your car. What sort of power (watts) do these beasts consume ? How long
would they normally last before they are replaced ?

Is there a special material/glass used to allow it to operate in extreme
conditions and most importantly, fairly rapidly changing temperatures
without cracking/failing ?

Are they designed solely "to be seen" or do they also help pilots see
what is out there ?