A lot of pilots don't use ILS and use a visual approach. That was one of the issues with the SF airport, as the left runway was closed, the lights were off and the pilot lined up with the taxi way.
While it is true that the normal lighting was off (because it wasn't a valid runway at the time), there was a lighted, flashing X to indicate that fact. Along with the fact that the taxiway was not illuminated as a runway, and the pilots were notified about the runway closure…
This is being downvoted, though is true to my understanding -- not uncommon for even the largest airports to have both ILS and non-ILS runways. (e.g. Runway 1L at SFO is non-ILS.)
In this particular case, the departure airport only had one runway, and immediately after the botched takeoff it was at least in dire need of a debris check, so I wouldn't be surprised if the airport was closed while that happened. Wouldn't have taken four hours, though, and I suspect that they would do whatever they could to accomodate an emergency aircraft had the pilot declared.
Maybe it didn't feel that bad in the cockpit, and the pilots were hoping they would wing it. They may have thought it would have endangered their jobs (which it certainly will...)
Usually in times of partial emergencies, there is a threshold point where you full own the emergency and declare it.
No, from the description, they clearly ignored reports that they "may have hit something", they said "nah, we good." It'll be interesting to see, when the passenger reports start coming in, whether it's plausible the pilots just didn't feel it.
The rules are based on the fact that landing is harder on the airframe than taking off, so as long as max takeoff weight is only a fraction higher than max landing weight you get a pass.
And at any rate you get the greater of 10 minutes or 1% of max takeoff weight per minute to dump enough fuel to land safely. I wonder how long it takes a 737 to circle the runway before it's safe?
20 percent of fuel is used from take off to cruise altitude. On a plane like a 777, that still leaves a very substantial amount of fuel onboard. However on a smaller plane like a 737, you don't have to circle for too long before you're below MLW.
Also, the airport wasn't good anymore. They had just destroyed the Instrument Landing System at the end of the runway. Nobody should land there.