Transit time, United to Primera at Newark

I'm going to take a different tack from the zillion-and-one questions about making connections at Newark-Liberty to highlight an issue that does not receive much attention at TSE.

Technically speaking, United doesn't fly SYR-EWR; it contracts that route to Commutair or ExpressJet dba United Express. That isn't a problem in and of itself, but those airlines operate so-called regional jets. As these are small planes, these flights are generally the first to suffer delays or cancellations for anything from a mid-afternoon thunderstorm to air traffic congestion, and Newark is in the most congested airspace in the country.

Second, Primera does not offer online check-in for Newark departures at this writing, and does not even offer self-service kiosks. Therefore, your son would need to exit the secure area after arriving (almost certainly at Terminal A), take the AirTrain to Terminal B, wait in line for check-in and document review at the Primera counter, then proceed back to TSA screening to get to the boarding gate.

Without checked luggage, this might be possible, but there is no margin for error. If there is any kind of flow control program in effect, if the ground services are short-staffed and there is a delay before the plane can park at the gate or allow passengers to disembark, if your son accidentally boards a train going the wrong direction, this will all make for an extremely stressful experience.

And because you would be buying the two tickets separately, as Primera does not have any partnerships with other airlines, you are assuming 100% of the risk. If there is a freak blizzard and your son misses the connection, Primera has no obligations to him. He is a no-show, and under the Conditions of Carriage you agree to when you purchase the ticket, the seat is forfeit. Most of the larger international carriers will, as a customer service gesture, let you stand by on a later flight, but ultra low-cost carriers are not known for their customer service.

I would allow ample time, four hours at a minimum. Airports are stressful enough as it is; there's little to be gained by adding to it with tight scheduling.

If this were a single ticket (you can have multiple flights on one ticket, but a single transaction with airlines that interline), 1:48 is sufficient time (depending on your tolerance for delays and the consequences of not making it to London as planned). However, with two separate bookings, it's risky, especially if he has any checked luggage.

With separate bookings, you are arranging your own connection and are responsible for the consequences. If his first flight is delayed, the second airline will not care, and you'll be responsible for the cost of a new flight, which can be substantial, along with expenses during the delay, potentially overnight. If your son has any checked luggage, he'll have to go to baggage claim, wait for the bags, and check them in for his next flight. And at Newark, he'll likely have to change terminals and go through security again. All of that will take a fair amount of time, more-so if he's unfamiliar with the airport or not an experienced traveler.

In short, I would not do this.