A schedule's late dates are calculated during the:

The backward pass is a core calculation within the Critical Path Method (CPM) used to determine a schedule's late dates. The process begins at the project's defined completion date (or the early finish of the final activity) and moves backward through the network logic. For each activity, it calculates the latest possible time it can finish (Late Finish) and start (Late Start) without delaying the overall project completion. This calculation is essential for subsequently determining the total float for each activity.

A. Loop calculations: Loops are logic errors in a schedule that create an infinite path, preventing valid date calculations like the forward or backward pass.
C. Forward pass: The forward pass calculates the earliest possible start and finish dates (Early Start and Early Finish) for each activity, not the late dates.
D. Float: Float (or slack) is a result, not a calculation process for dates. It is calculated after both the forward and backward passes are completed.

1. AACE International. (2023). Recommended Practice 10S-90: Cost Engineering Terminology. Section 3, Definitions.

Backward Pass: "Calculation of late finish and late start dates for the uncompleted portions of all network activities. Determined by working backwards through the network logic from the project's end date."

Forward Pass: "Calculation of the early start and early finish dates for the uncompleted portions of all network activities. Determined by working forward through the network logic."

2. Hollmann, J. K. (Ed.). (2015). AACE International's Skills & Knowledge of Cost Engineering (6th ed.). AACE International.

Section 2.4.11, Critical Path Method (CPM) Scheduling: "The backward pass calculation starts at the end of the project... and works backward to the start of the project... The backward pass calculation determines the latest that each activity can start (late start) and finish (late finish) without delaying the completion of the project."

3. MIT OpenCourseWare. (2012). 1.040 Project Management, Spring 2012. Lecture 5: Project Scheduling: PERT/CPM.

The lecture notes explicitly define the backward pass as the method to compute the Late Start (LS) and Late Finish (LF) for each activity, starting from the project's end and working backward.