Four planes were stuck on the tarmac for more than three hours in April, according to the latest report released by the government. U.S. Airlines also had some trouble overall getting passengers on time to their final destination.

Out of the four tardy flights, three were operated by Delta and one by United. Three of the four were later cancelled. Thunderstorms played a big role in delays, as they normally do around the country during the month of April.

Weather issues seem to have been the main problem for airlines during April. On-time rates by the top 16 airlines in the United States was 75.5 percent, down greatly from a year ago when they averaged 85.5 percent.