It really doesn't matter if the plane is scheduled to go out 5 minutes before Shabbat ends. That will not discourage anyone from being on the flight.

Even if the plane were scheduled to take off 1 hour after Shabbat is over there would not be a single Shabbat-observant Jew on it.

In the most extreme case someone who wanted the earliest possible flight would be staying at a hotel at the airport. The moment that Shabbat ended, he would get a taxi directly to the hotel (let's say this takes 5 minutes). He would have to plan for a minimum of 30 minutes for check in and El Al Security (and we all know that is cutting it very close).

Then he would have to go to the Gate (say a 10 minute walk) and, on his way, go through Passport Control (5 minutes) and LHR airport security (another 10 minutes).

All of this would take a minimum of 1 hour -- and he would have to hope that boarding is still open.

Given all of that, why does it matter when the flight is scheduled to take off (assuming that it doesn't actually begin flying until after Shabbat)?