Per-diem
Crew per-diem is the daily allowance for pilots and cabin crew who stay away from base during your trip, covering hotel, meals and transport. On multi-day charters it is billed either as a fixed figure per crew member per night, typically $250–$600 depending on the city, or at cost with receipts. Two pilots waiting three nights in Zurich can easily add $3,000 to a quote. The alternative is to release the aircraft after drop-off and charter a fresh one for the return, which avoids per-diem and daily minimums but exposes you to spot-market prices and availability. Ask that per-diem be shown as a line item rather than buried in a lump sum.