There was chaos around Ohakea air base on Saturday with traffic backed up for several kilometres as thousands of people tried to get into an air force display.
The Defence Force says about 60,000 people tried to attend the show to celebrate the Royal New Zealand Air Force's 75th anniversary.
Officials extended the ground display and urged spectators to delay leaving the site after the show to avoid causing another traffic backlog similar to the one that occurred on Saturday morning.
The police fielded a number of calls from frustrated motorists caught in what was described as chaos.
Motorists stuck in gridlock also took to the social network sites Twitter and Facebook to air their frustrations, with some complaining they had to turn back after being stuck in traffic for at least two hours.
The police say officers were placed on all major intersections out of Ohakea air base to control the traffic exiting the show.
A spectator, Glenn Inwood, says getting away from the base itself was the big problem on Saturday afternoon and he took a short-cut.
"There are two large carparks and only two ways out. And every car is trying to get out as quicky as possible. We found a way out through a back fence," he said.
Every available highway unit in the Palmerston North area was in attendance and traffic was reported at one point in the morning to be jammed in all directions on State Highways 1 and 3.
A resident who lives about three kilometres from the airbase, Ken Biblake, says it was impossible for traffic to move at one point.
"The traffic has been banked up here for the last two hours for several kilometres," he said at about 11.30am.
"People are abandonning their cars and walking, and I've actually seen someone reversing down the road on the wrong side of the road. It is absolute chaos."
The air show was to include international and New Zealand military and civilian aircraft, some dating back to the First World War.
Iroquios helicopters, which are set to be phased out by 2014, will be flown alongside the machines replacing them, the NH90s.
The Royal Australian Air Force and the United States Air Force also put on displays.
Organising committee chair Wing Commander Phill Bedford says it is an opportunity to celebrate 75 years of the Royal New Zealand Airforce.
The celebrations carry on until next month and will include parades in Wellington and Auckland.