Improved alterting and TZ handling

README.md

@@ -116,13 +116,16 @@ To migrate data from the old system:
 2. Transform to new schema format
 3. Import into the new system
 
-## Security
+## Time Zone Handling
 
-- JWT token authentication
-- Password hashing with bcrypt
-- Input validation with Pydantic
-- SQL injection protection via SQLAlchemy ORM
-- CORS configuration for frontend integration
+The system uses UTC (Coordinated Universal Time) as the standard for all time storage and display in aviation contexts:
+
+- **Database Storage**: All times are stored in UTC
+- **Admin Console Display**: Times are displayed in UTC (with Z suffix)
+- **Data Entry**: Times are entered as local time in the New PPR entry form, then automatically converted to UTC for storage
+- **API**: All datetime fields in API responses are UTC ISO strings
+
+This ensures consistency across different time zones and complies with aviation standards where UTC is the international standard.
 
 ## Performance