The AIM-9X missile is still heat seeking, and requires a predetermined, concentrated heat level. Early versions of the sidewinder missile had problems with "tracking" the sun or hot jungle floors. Now, the missile will only lock onto targets that are hotter than the jungle floor, but not as hot as the sun (i.e. enemy fighters). The electronics are fairly sophisticated.
Also, the helmet mounted sight cannot override the missile's tracking system. It can only designate where the missile should start looking for heat signatures. So all those hopes that some pilot notices your ex and winks at her, thus ensuring her death are pretty much mute (unless your ex is really hot...)
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The AIM-9X missile is still heat seeking, and requires a predetermined, concentrated heat level. Early versions of the sidewinder missile had problems with "tracking" the sun or hot jungle floors. Now, the missile will only lock onto targets that are hotter than the jungle floor, but not as hot as the sun (i.e. enemy fighters). The electronics are fairly sophisticated. Also, the helmet mounted sight cannot override the missile's tracking system. It can only designate where the missile should start looking for heat signatures. So all those hopes that some pilot notices your ex and winks at her, thus ensuring her death are pretty much mute (unless your ex is really hot...)