The peak season for traveling via airplane to Peru runs from July to August, coinciding summer vacations for teachers and students.  Tickets in September sell out rather quickly, however, because air fares drop, and December is a busy time as well due to the high number of Peruvian immigrants returning home to visit their families. During anytime of the year, there is a departure tax of approximately $30.
The main carriers offering flights from North America are Delta, Continental, American Airlines and three Latin American-based airlines: Lan Peru, Paca, and Copa. Paca offers flights from Miami to San Jose, Costa Rica, and from there to Lima, while Copa stops first in Panama City.
The main carriers from the UK are Lufthansa, American Airlines, Continental Airlines, Delta Airlines (via the US), United Airlines (via the US), Iberia, (via Madrid), KLM (via Amsterdam).
From Australia and New Zealand one can take Air New Zealand, Aerolineas (an Argentine airline), Lan Chile, Quantas, and United Airlines.