ModeratePhysical Estimation reported at Accenture

Flights Taking Off from Delhi Airport in a Day

Scope it first — questions to ask

· Take-offs only, or total movements (landings + take-offs)? — Scope: take-offs (departures) only.
· Passenger + cargo + general aviation, or scheduled passenger flights only? — Scope: all departures (cargo/GA is a small add-on anyway).
· Average day or peak season? — Scope: an average day.

Assumptions on the table

· Delhi (IGI) has 4 runways with about 3 usable for simultaneous operations — one of the busiest airports globally.
· At busy times each active runway handles a movement every ~3 minutes → ~20 movements/hour/runway, i.e. ~60/hour for the airport.
· The airport runs ~20 busy hours a day; the 4 lean overnight hours (1–5 am) drop to ~20 movements/hour (cargo, red-eyes).
· Departures and arrivals are roughly 50:50 over a full day — what takes off must have landed.

The worked solution

Active runways

4 built, ≈ 3 in simultaneous use

Busy-hour throughput

3 runways × 20 movements/hr = 60/hr

Busy-hours movements

60 × 20 hrs = 1,200

Lean-hours movements (1–5 am)

20 × 4 hrs = 80

Total daily movements

1,200 + 80 ≈ 1,300

Departures (half of movements)

1,300 ÷ 2 ≈ 650 take-offs

Busy hours (5 am – 1 am)

Hours20

Movements/hour60 (3 runways × 20)

Movements1,200

Lean hours (1 am – 5 am)

Hours4

Movements/hour20

Movements80

Total movements

Hours24

Movements≈ 1,300

Take-offs (÷ 2)

Movements≈ 650

Answer

≈650 take-offs/day

Full calculation

Window	Hours	Movements/hour	Movements
Busy hours (5 am – 1 am)	20	60 (3 runways × 20)	1,200
Lean hours (1 am – 5 am)	4	20	80
Total movements	24		≈ 1,300
Take-offs (÷ 2)			≈ 650

Sanity check

Demand-side cross-check: ~70M passengers/year ÷ 365 ≈ 190K/day; half are departing (~95K) ÷ ~160 passengers/flight ≈ 600 departures. Supply (650) and demand (600) converge — the estimate is robust.

The lesson to carry

Physical estimations are capacity × utilization problems — build from the bottleneck (runway slots), then validate with an independent demand-side approach.

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