Despite the high number of black helicopters flying over downtown Chicago this week, the city is not hosting another filming of a "Batman" or "Transformers" movie. Instead, it's hosting another military training.

The City of Chicago holds a routine military training exercise in the Chicago area for a week every year and warns of increased aircraft activity, including helicopter flights, during this time.

This year's training is held July 20-25, and the increased helicopter presence has not escaped Chicago residents, who have taken to Twitter to report their sightings.

The low-range flying may scare some residents, but city officials say it fits the federal, state and city standards. And Chicago is not the only city that undergoes the training.

"This routine training is conducted by military personnel in cities across the country, designed to ensure the military's ability to operate in urban environments overseas, as service members meet mandatory training certification requirements and prepare for upcoming deployments worldwide," according to Office of Emergency Management and Communications.

Training exercises are not open to the public and are designed to limit the disruption of Chicago residents.