To David
Hancock
The offset is wrong
for the airport MMHO Hermosillo in your data because you encoded it wrongly as
America/Chihuahua, while it should be America/Hermosillo. You had a typo in the
email which spelled it Hermisillo, I don't know if that is a simple typo when
sending or it was the root of the problem. Hermosillo is in the state of Sonora,
which is the only state in Mexico that does not use Daylight
Saving.
Regards,
Jesper Nørgaard
Welen