Another option is the Air Deccan flight from Pathankot (3hrs by bus or 1.5hrs by taxi from Dharamsala). If you book online, the flights are ridiculously cheap. Taking that into account, the airline doesn't have the greatest reputation. A sense of humour certainly goes a long way when dealing with the safety and service standards! When I caught it, the flight was delayed by a couple of hours owing to problems at the Delhi end (this can be expected). But I was so relieved the thing actually turned up I didn't care. In general though, internal air travel in India is best avoided at the moment - although the north lacks train lines, there are plenty of bus services that can be booked on the day.