Air travel in America has gotten a lot less pleasant in recent years. But even with free meal service now a thing of the past and airlines cramming more seats into less space, the worst thing for travelers is when planes don't arrive on time.

But on-time arrivals aren't just important for you and the millions of other travelers trying to make connections or stay on schedule for business or pleasure. They also have a big impact on the reputation of airlines that strive for good customer service. With that in mind, let's take a look at some numbers that Bloomberg collected about the U.S. airports with the worst on-time arrival records in 2012, and the effects they might have on the airlines that call them home.

Newark Liberty, 69.44% flights on time in 2012


Source: Port Authority of New York & New Jersey.

Newark weighed in with the worst on-time arrival record of all airports for the second year in a row, but it posted strong improvement from an even worse 66.72% record in 2011. One big problem Newark faces is being in the middle of some of the most heavily congested airspace in the nation, especially with shuttle flights between Boston, New York, and Washington adding to air-traffic complications. Newark is a big hub for United Continental (UAL 0.17%), given the high demand for passengers coming into and out of New York City as well as for international connections. But Newark also has a thriving cargo business, and FedEx (FDX 0.59%) has the second-largest presence at the airport after United Continental.

San Francisco, 69.95% on time


Source: San Francisco International Airport.

San Francisco narrowly avoided taking over the top spot from Newark, with its track record the only one among the top five to get worse from 2011 to 2012. San Francisco is famous for its unpredictable weather patterns, with fog often causing unavoidable delays in addition to the ordinary difficulties in maintaining on-time operations. Because of its weather-related complications, San Francisco isn't really suitable as a domestic hub, but its strategic location as a gateway to the Pacific Rim still forces airlines to brave the tough conditions and use the airport to support their flight schedules to Asia. United in particular maintains a significant presence there.

LaGuardia, New York, 76.75% on time


Source: Port Authority of New York & New Jersey.

LaGuardia's Long Island location leaves it susceptible to many of the same complications that Newark faces, including heavy traffic conditions and unpredictable weather, especially in winter. But LaGuardia has worked hard to improve its on-time record. After reporting only 72.18% on-time arrivals in 2011, the airport posted the best improvement in 2012 of the five airports listed here. LaGuardia provides a more convenient location for many travelers coming into New York than Kennedy or Newark, and that makes many travelers more willing to deal with potential delays getting there. Delta Air Lines (DAL 0.43%) and American Eagle Airlines use LaGuardia extensively to support their overall operations.

Washington Dulles, 79.15% on time


Source: Metropolitan Washington Airports Authority.

Serving the nation's capital, Dulles has to deal with heavy and sometimes unpredictable flows of travelers in and out of Washington. Coming into and out of Dulles in the air also involves complying with special flight restrictions in and around the capital city; as a result, air-traffic controllers have to use complex flight patterns to coordinate traffic. The presence of Reagan National Airport and its own set of flights adds further complications. United uses Dulles as a hub airport, which improved its on-time record slightly from 78.61% in 2011.

Chicago O'Hare, 79.63% on time


Source: Chicago Department of Aviation.

O'Hare is notorious for its windy conditions year-round, and a combination of thunderstorms during the summer months and heavy snow during winter inevitably hurt its on-time performance. But even with those obstacles, the airport has worked hard to get more of its flights on schedule, with gains in its on-time record of more than four percentage points from its 75.48% showing in 2011. Chicago's placement roughly halfway between the East and West Coasts make it a logical place for an airline to put a central hub of operations, and geography is a big part of the reason why both American Airlines (NASDAQOTH: AAMRQ) and United have extensive hub operations at O'Hare.

Good luck avoiding these airports
With the continuing consolidation in the airline industry, it's getting harder to avoid unwanted side trips to hub-city airports. Southwest Airlines (LUV -0.91%) stubbornly continues to run a significant part of its schedule using point-to-point service rather than using hubs, but even it uses airports like Chicago Midway and McCarran International in Las Vegas as hub-like areas. For the most part, travelers can only hope that they'll be the lucky ones to end up arriving on time.