The Douglas A4D Skyhawk was roughly half the empty weight of its contemporaries and could fly at 677 mph at sea level. After 1956, it had provisions for in-flight refueling, and it carried anti-radar missiles on its wing racks. After 1966, it included a hump-like avionics pod. Upgraded models had improved engines and a drogue parachute, new avionics displays, larger cockpit canopies, and more ammunition for the two cannons.