Here are the basic steps to create the Saved Search:
1. Navigate to Lists > Search > Saved Searches > New.
2. Select Customer.
3. Choose filters in the Criteria tab (optional).
4. In the Result tab > Columns subtab, select the joined field of the Custom record Flight Details fields…
5. Select the field Flight Hours in the pop up window.
6. Set Sum as its Summary Type.
7. Set Group as the Summary Type of the field Name.
8. Click Save & Run.
The Saved Search should now show you the names of your Customer records with the total Flight Hours accumulated from multiple entries. When you click on the name of the Customer, it will show you the drilldown of how many Flight Hours there are per entry.