Work phase 2

Example 1 Why missions start late

Causes of missions starting later than scheduled over two months (hypothetical data).

delays = {"weather": 18, "battery not charged": 11, "missing permit": 7,
          "GNSS/compass issue": 5, "crew late": 3, "software update": 2}
total = sum(delays.values())
cum = 0
for cause, n in sorted(delays.items(), key=lambda kv: -kv[1]):
    cum += n
    print(f"{cause:<20} {n:>2}  {n / total:5.1%}  cumulative {cum / total:5.1%}")
controllable = {k: v for k, v in delays.items() if k != "weather"}
top = max(controllable, key=controllable.get)
print(f"largest cause the team controls: {top} ({controllable[top] / total:.0%} of all delays)")

weather              18  39.1%  cumulative 39.1%
battery not charged  11  23.9%  cumulative 63.0%
missing permit        7  15.2%  cumulative 78.3%
GNSS/compass issue    5  10.9%  cumulative 89.1%
crew late             3   6.5%  cumulative 95.7%
software update       2   4.3%  cumulative 100.0%
largest cause the team controls: battery not charged (24% of all delays)

Weather is the largest cause but cannot be controlled. The largest cause the team does control is batteries not ready, which makes a good project topic.

Example 2 Plan for a battery status system project

Tasks (working days) and the tasks that must finish first.

tasks = {   # task: (days, predecessors)
    "A study current process": (3, []),
    "B root-cause analysis": (2, ["A study current process"]),
    "C design status labels & checklist": (3, ["B root-cause analysis"]),
    "D charging schedule": (2, ["B root-cause analysis"]),
    "E pilot test": (4, ["C design status labels & checklist", "D charging schedule"]),
    "F train crew": (2, ["C design status labels & checklist"]),
    "G measure & report": (3, ["E pilot test", "F train crew"]),
}
es, ef = {}, {}
for t, (d, pre) in tasks.items():
    es[t] = max((ef[p] for p in pre), default=0)
    ef[t] = es[t] + d
end = max(ef.values())
lf, ls = {}, {}
for t in reversed(list(tasks)):
    succ = [s for s, (_, pre) in tasks.items() if t in pre]
    lf[t] = min((ls[s] for s in succ), default=end)
    ls[t] = lf[t] - tasks[t][0]
for t in tasks:
    slack = ls[t] - es[t]
    print(f"{t:<36} ES {es[t]:>2} EF {ef[t]:>2} slack {slack} {'CRITICAL' if slack == 0 else ''}")
print(f"project duration {end} working days")

A study current process              ES  0 EF  3 slack 0 CRITICAL
B root-cause analysis                ES  3 EF  5 slack 0 CRITICAL
C design status labels & checklist   ES  5 EF  8 slack 0 CRITICAL
D charging schedule                  ES  5 EF  7 slack 1
E pilot test                         ES  8 EF 12 slack 0 CRITICAL
F train crew                         ES  8 EF 10 slack 2
G measure & report                   ES 12 EF 15 slack 0 CRITICAL
project duration 15 working days

The critical path is A–B–C–E–G, 15 working days in total. The charging schedule (D) has one day of slack and crew training (F) has two. If the mentor is unavailable during the pilot test (E), the project slips immediately, so book that time early.