Based the following, why would airports have pre-planned standby positions? Imagine an airport and all of the airplanes that must use the same runways. Sometimes the paved road or shortest distance to the crash site is occupied with other aircraft, so fire stations must run training scenarios on alternate routes. Most airports have created emergency roadways specifically for this purpose. They also have pre-planned standby positions where firefighters can wait for an aircraft that has initiated a call for help as a warning for a possible crash landing.

an airplane experiences a flat tire while taxiing to the gate
an airplane experiences a flat tire while taxiing to the gate

a small electrical fire has been detected on a plane as passengers are boarding
a small electrical fire has been detected on a plane as passengers are boarding

a pilot reported she is hearing an alarm as the plane waits for takeoff
a pilot reported she is hearing an alarm as the plane waits for takeoff

a co-pilot calls in that smoke is filling the cabin as the plane approaches for landing
a co-pilot calls in that smoke is filling the cabin as the plane approaches for landing