Field help (KARVEXPDAT) 

If you have entered a transport number, the planned arrival date linked to the transport is automatically displayed and cannot be modified.
If you need to modify this information, delete the transport number and save.

If you have not entered a transport number, the planned arrival date is automatically calculated based on the departure date as follows:

Arrival date + Transport lead time between the departure place and arrival place + release lead time at arrival place+ potential days difference entered manually in the function.

The transport lead time considered between the departure place and arrival place is the one defined for the specified transportation mode and carrier. 
If this setup does not exist for the given carrier, the transport lead time defined for the transportation mode is considered. If no setup has been defined for this transportation mode, then the transport lead time defined between the departure place and arrival place is considered. Otherwise, the calculation is performed with no transport lead time.
The calculated date remains available for modification.

For example:
Let us consider the following transport lead times defined between Paris (departure place) and Geneva (arrival place):
Line 1: Carrier: DHL - Transport mode: AIR --> 1 day
Line 2: Carrier: DHL - Transport mode: ROAD --> 2 days
Line 3: Carrier: ---    - Transport mode: ROAD --> 2 days
Line 4: Carrier: ---    - Transport mode: not defined --> 4 days

The considered transport lead times are:

SEEINFOIn order to calculate the planned receipt date of order lines when the arrival date has not been specified, the planned arrival date is used.