Makes me think that the Embraer must be a very marginal aircraft for Southend if it cannot fly a domestic route without offloading passengers while for Easyjet and Ryanair it was just another day unless they also had to off load passengers which wasn’t reported.
Found this very interesting article about air density and other weather issues making a difference to runway performance.
https://www.skybrary.aero/index.php/...eoff_and_Climb