Ten days after an equipment malfunction left about a dozen planes flying blind for 90 seconds in the crowded skies over New Jersey, worried pilots and air traffic controllers are imploring the Federal Aviation Administration to fix the system’s aging infrastructure.

The “shell-shocked” controllers who guide planes in and out of Newark Liberty International Airport work in constant fear of radar systems’ going down or losing radio contact with pilots as they’re approaching one of the busiest airports in the country, a recently retired controller told NBC News.

Both of those failures happened at once on April 28.