The main idea here is that weather can change after a flight plan is amended, so you must recheck weather information when a plan is adjusted for a ground delay. A new departure time means the forecast for winds aloft, temperature, icing, turbulence, and convective activity can be different, which can affect fuel needs, routing, and potential alternates. By reviewing updated weather data—METARs, TAFs, SIGMETs/AIRMETs, radar, and weather charts—you can confirm that the chosen route and alternate airports remain safe and feasible within your fuel reserves, and you can adjust the plan if necessary. Passenger lists, maintenance issues, and airport fees aren’t directly involved in whether the amended flight plan remains viable from a weather and safety standpoint, so they don’t carry the same impact on the plan’s feasibility as updated weather information does.

Rudders control yaw—the rotation of the aircraft's nose left or right about its vertical axis. The rudder is the vertical tail surface you deflect to create a side force, which changes the aircraft’s heading without directly changing its pitch or altitude. Pitch is controlled by the elevator (nose up/down) and roll by the ailerons (wing tilt). The rudder helps with coordinated turns, preventing adverse yaw, and is especially useful in handling crosswinds or engine-out situations.

Two independent oxygen systems cover the airplane: one for the cockpit crew and one for the passenger cabin. The cockpit system has its own supply and masks so pilots can maintain control and operate the aircraft even if the cabin system is deployed. The passenger system provides oxygen to passengers via overhead masks, typically activated automatically with cabin depressurization. Having these two separate systems ensures a reliable oxygen supply for both flight crew and passengers, and prevents a problem in one system from compromising the other. The idea that there’s just one cockpit system, three systems, or only passenger systems doesn’t match how the 737 is designed.

Class B airspace around the nation's busiest airports is built in layered shelves that extend from the surface up to a ceiling of 10,000 feet above mean sea level. The important point is that the top of Class B is 10,000 feet MSL, even though the bases of those shelves can start at different altitudes. This structure keeps all traffic within a clearly defined, highly controlled zone and requires explicit ATC clearance to enter, along with two-way radio communication and an altitude-reporting transponder. Phrased differently, it’s not from the surface to 4,000 feet, nor does it extend up to 12,000 or 18,000 feet—the standard ceiling is 10,000 feet.