Airline travel delays pick up early, expected to grow steadily worse

Travellers are getting hit with delays at US airports again early on Wednesday, an ominous sign heading into the long July 4 holiday weekend, which is shaping up as the biggest test yet for airlines that are struggling to keep up with surging numbers of passengers.

As of early morning, more than 900 flights have been delayed in the US, according to FlightAware. Cancellations topped more than 670 flights.

Cancellations and delays were most severe along the East Coast early and were growing worse rapidly. Disruptions are expected to spread West.

The delays are being compounded by thunderstorms that raked the Northeast on Tuesday. At various times, the Federal Aviation Administration held up flights bound for LaGuardia Airport in New York and Reagan Washington National and Baltimore-Washington airports near the nation's capital.

About 6,500 flights were delayed and about 1,900 cancelled on the East Coast on Tuesday. United Airlines, with a major hub in Newark, New Jersey, cancelled ab