An earlier suicide bombing Thursday killed at least nine people and wounded 16 others at an army recruitment center in Baghdad, Iraqi police said.
The airfield incident happened as the recruits waited to enter the base, the New York Times reported.
"We came to join the army to fight al-Qaida, and this will not stop us," Ali Jasim, a recruit at the base, said in a telephone interview after the blast.
Jasim said the attack was an effort to stop the flow of government troops to parts of Baghdad where al-Qaida fighters have taken control.
"We are here to die for our country; we've had enough of them," Jasim said of al-Qaida. "They targeted us today because they are afraid of us reaching there."
Meanwhile, U.S. defense officials said the U.S. military has begun pushing for Iraq to allow resumption of U.S. training of Iraqi commandos to prevent future attacks, the Wall Street Journal reported.
U.S. officials said they have talked about the proposal with Iraqi officials, but don't know if Baghdad will agree to it. The proposed training would occur in Jordan.
The airfield bomber arrived on foot, not in an explosive-laden vehicle as originally reported, CNN said
Officials said most of the victims were men waiting to enter the recruitment offices.
News of the suicide bombing came the same day Human Rights Watch issued a report saying Iraqi government forces appear to have used indiscriminate mortar fire in civilian neighborhoods in Anbar province while al-Qaida fighters and armed men from local groups have deployed in and attacked from populated areas.
The Human Rights Watch report criticized all sides in the renewed violence in Iraq that has caused civilian casualties and property damage.
HRW noted a government blockade of Fallujah and Ramadi -- areas of which have been seized by Iraqi militants with ties to al-Qaida -- resulted in limited access to food, water and fuel.
"The government urgently needs to deal with the threat from al-Qaida, but killing their own citizens unlawfully is not the way," said Sarah Leah Whitson, Middle East and North Africa HRW director. "Civilians have been caught in the middle in Anbar, and the government appears to be doing nothing to protect them."