Pakistan Airlines operates daily 2 flights from Islamabad to Gilgit, leaving daily at 0645 am and 0945 am (please check PIA website as time may change from season to season). Planes are new ATR 42-500, twin propeller with a seating capacity of 48, which have replaced the ageing fleets of FOKKER-F27. You need to book in advance for these flights as seats are limited or over-booked. Check with a travel agent or PIA office at the mall in Rawalpindi for more info.
It is an awesome flight flying over gorges, rivers and mountains and a breathtaking view of Nanga Parbat (usually if you sit on the right side of the plane). It also flies over Saiful Muluk Lake in Kaghan and you can also see this beautiful alpine lake set in-between various mountain ranges.
It takes over an hour to reach Gilgit, and is weather dependent, so be prepared for delays or cancellations.
Picture taken from PIA website.
The only aeroplane which goes to Gilgit is the oldest aeroplane in the Pakistan International Airlines Fleet (probably the oldest in the world also !!). The plane is the F27 Fokker which has a lot of improvements needed in its structure. There are quite a few shocks and other things. However, the flight is pretty beautiful and safe and gives an awe-inspiring view of Nanga Parbat. The view of the mountains and the landscape is brilliant and you must try this flight at least once in a lifetime. The flights are dependant on the weather (there is 50 % chance of cancellation) even though I never understand this, how can weather affect an aeroplane over a mountainous arid DESERT of Kohistan where there is less than 4 inches of rain a year. Probably they take another route. The landing on the Gilgit Airport is a bit scary as the Runway length is only about 600 m (NOT JOKING). However, thankfully no incidences have ever happened up to date. However, 2 planes have crashed in flights to Skardu (Baltistan) from Islamabad. The first crashed plane was found and made into a restautant (quite convenient). However, the scary part is that the other aircraft's BODY wasnt found-----not anywhere just disappeared (this isnt Bermuda Triangle) and that plane was a Boeing 747.
There are about 2 flights to Gilgit every day and they leave only from Islamabad Airport. Hunza is about 2 hours drive north from Gilgit.