Examples of planes that can be fitted with this upgrade include the Boeing 737-200, which includes a gravel deflector (similar in appearance to a wide ski) mounted to the nose wheel, and vortex dissipators, using compressor bleed air, in front of each engine. This modification was used by Alaska Airlines for many years, and is still employed by Air Inuit, Canadian North, Air North, Nolinor Aviation and First Air in northern Canada. Some Boeing 727s were also fitted with specific gravel kits on the nose wheel, while the rest were fitted with devices in the form of smaller deflectors than those used on the 737, used on all wheels, to deflect FOD away so as to prevent the rear-mounted engines from ingesting FOD from a runway.