Silence. That’s the last thing an airline pilot wants to hear from air traffic control as they approach a major international airport straddling the country’s most populated city.

NEWARK, N.J. (AP) — Flight delays and cancellations persisted at Newark Liberty International Airport Monday, with Senate Minority Leader Chuck Schumer calling for an investigation into the “chaos” sparked by an air traffic controller shortage and thick cloud cover.

Travelers are advised to consider alternative airports or United hubs to avoid the ongoing flight delays and cancellations at Newark.