Gloria... the proper sentences should be written as follows: You can change to the next Air China flight. When [at what time] is the next one [the next flight]?

I can understand why this is confusing for you. I will try to explain. The words "near and close" are almost always used to describe distance. Sometimes they are used to describe time, actually they are used to describe how close we are to a specific time, e.g., It's April, so Christmas is not close or near. Near, when used to describe time, refers to the amount of time that is left before something happens, e.g. The bus was going to leave (depart) at 4:00, and it was 3:55. So, the departure time was near. Now, in your example about the buses, when we use "near" or "close", people will usually think that you are describing the distance between you and the bus. That means that you have to be specific about whether you are referring to (talking about) the distance or the time of departure. Therefore, if you are referring to the time of departure (the departure time) you must include the expression "departure time". So, if it is 9:00, and the next 3 buses leave at 10:00 11:00 and 12：00, then the nearest departure time would be 10:00. We have a way of reducing the number of words, i.e., "the nearest departure time" by simply saying "the next bus", e.g., The next bus leaves (departs) at 10:00. So, next bus means the bus that will leave at the earliest time, and the bus that leaves at 12:00 would be the bus that leaves at the latest time. So, you can use "the nearest departure time is..." or you can say "the next bus departure time is/the next bus departs/leaves at...". It that any clearer?

I can understand why this is confusing for you. I will try to explain. The words "near and close" are almost always used to describe distance. Sometimes they are used to describe time, actually they are used to describe how close we are to a specific time, e.g., It's April, so Christmas is not close or near. Near, when used to describe time, refers to the amount of time that is left before something happens, e.g. The bus was going to leave (depart) at 4:00, and it was 3:55. So, the departure time was near. Now, in your example about the buses, when we use "near" or "close", people will usually think that you are describing the distance between you and the bus. That means that you have to be specific about whether you are referring to (talking about) the distance or the time of departure. Therefore, if you are referring to the time of departure (the departure time) you must include the expression "departure time". So, if it is 9:00, and the next 3 buses leave at 10:00 11:00 and 12：00, then the nearest departure time would be 10:00. We have a way of reducing the number of words, i.e., "the nearest departure time" by simply saying "the next bus", e.g., The next bus leaves (departs) at 10:00. So, next bus means the bus that will leave at the earliest time, and the bus that leaves at 12:00 would be the bus that leaves at the latest time. So, you can use "the nearest departure time is..." or you can say "the next bus departure time is/the next bus departs/leaves at...". It that any clearer?