Do I need the Tibet Permit for book a Flight (E-Ticket) from Chengdu to Lhasa?

Yes, usually Tibet Travel Permit is required for foreigners to book the flight tickets to Lhasa and board on the flight successfully. You would better apply for it in advance.

Ok, thanks. So how does it work if I will book via Travelchinaguide.com? Do you need a copy of my TTP before I start the booking-process? In the past I pick up the tickets from the airport, so this doesn't work if I book now, and bring the TTP to the airport, right?