The main airlines serving Chad are Sudan Airways, Ethiopian Airlines and Cameroon Airlines, which connect N'Djaména with major West and Central African cities at least once a week, including Khartoum and Addis Ababa. Some European destinations are also covered, and Air France flies to Paris up to four times weekly. The airport departure tax is officially USD 8.50 for international flights, but you may be asked for twice that.
Chad's borders with Libya and CAR are not currently considered safe for travellers. Travel between Chad and Niger or Sudan is theoretically possible, it's just a very difficult thing to make happen. Arranging permission can be very time-consuming. The overland route from N'Djaména to Khartoum is a real desert epic, often involving some hitching, and can easily take a week or more. There is no direct transport; the usual route is from Abéché via Adré, Al-Geneina, Nyala and El-Obeid. You should expect to change transport (and spend a day or two waiting for lifts) in each of these staging points. Note that the area around the Chad-Sudan border has been drawn into Sudan's civil war, and is currently a no-go area. Driving time from N'Djamena to Maroua in Cameroon is about four hours; the border post is open from 06:00 - 17:30 . To get to or from Niger is easy on a paved road linking N'Djamena and Maiduguri. The more adventurous should try the direct route through eastern Niger from Zinder, passing north of Lac Chad. Coming into Chad, you're meant to pick up a guide at the border, but some report getting away without one. Offering a lift to someone in uniform will speed your journey considerably. Bring your own petrol.
Flying around Chad is often the only practical option, with flights costing, on average, USD 70.00 . In Chad, buses are nonexistent. Trucks, pick-ups and minibuses are your main choice for cross-country travel. Most of Chad's roads are dirt tracks (pistes), making travel uncomfortable at the best of times and extremely difficult in the rainy season. Within towns, taxis and minibuses are common; outside N'Djaména you'll also find fleets of clandos (motorcycle taxis).