Why my nexus 5 is not getting on air update for Android 4.4.2 In India there are some Nexus 4 which got updates for Android 4.4.2 but my Nexus 5 is not even updated to 4.4.1, Who can let me know how this OTA works with Google?
The roll-out for all (or at least most) OTA updates is staged in case there is an issue which has not been noticed. The 4.4.2 update seems to be being rolled out quicker than the 4.4.1 update, but it won't be available to all devices at the same time. You should receive the update in a few days.

This post by an android engineer explains the process a bit better but i've extracted some of their post here:


  Morrill mentioned how they “typically” begin with 1 percent of devices
  for the first day or two. This small batch is sent out and Google then
  watches for “return rates and resulting device checkins and error
  reports.”
  
  Assuming the initial 1 percent rollout goes according to plan, the
  process then expands. Again, the word typically was used. But in this
  case Morrill said the updates then go to 25 percent, 50 percent and
  100 percent “over the course of a week or two.”