Norcal Approach

Owen Becker

Filing Flight Plan
Joined
Nov 14, 2018
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7
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San Francisco
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Owen Becker
Situation: I'm on Norcal approach and they have already given me a squawk and altimeter setting. I am flying over KCCR where a couple of minutes later another aircraft is also transitioning over KCCR. NorCal gives them a different altimeter setting than what I have.

Question is since my aircraft and the other aircraft are in the same area, shouldn't we both be using the same altimeter? I know I have been told to use whatever altimeter setting ATC gives me, but wouldn't it be logical to use the same one? Why wouldn't I switch to the other aircraft's altimeter setting?
 
Is it possible that the field changed the altimeter setting they were reporting during the few minutes involved? If so, then you should use the latest setting. If not, an inquiry to ATC would have been in order to clarify which was the correct setting.
 
Situation: I'm on Norcal approach and they have already given me a squawk and altimeter setting. I am flying over KCCR where a couple of minutes later another aircraft is also transitioning over KCCR. NorCal gives them a different altimeter setting than what I have.

Question is since my aircraft and the other aircraft are in the same area, shouldn't we both be using the same altimeter? I know I have been told to use whatever altimeter setting ATC gives me, but wouldn't it be logical to use the same one? Why wouldn't I switch to the other aircraft's altimeter setting?

Might have been destination altimeters. One of you might have been on the way to say OAK and the other to maybe APC. It would be appropriate for you to each have been given the destination altimeters by the time you were in the neighborhood of CCR
 
Probably depends on how much difference there is between the settings. If it was enough to cause a problem the controller would see your altitude and tell you current setting, or perhaps ask you to say your altitude.
 
I have always viewed the local altimeter from the controller as informational, not necessarily an instruction. It is not a mandatory readback. When going cross country it is really convenient to not have to tune the local weather (or now, press buttons on the gtn) to get the local altimeter setting. When you are about to land, you should never leave the altimeter setting to what the controller told you. Destination weather should be your only source for that. Common sense to people who fly instruments, maybe not as much for vfr only guys.
 
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