The correct answer to this open question is the following.
The data collection methods I think would be the most useful in providing this evidence would be interviews, focus groups, and observations.
I would use these methods because they are effective methods to prove that the design of the training and the response of the participants are the required ones to see advancements. Through these methods, I can confirm that flight attendants understand the procedures and use them on the job.
The type of learning outcome could affect my choice of measuring learning in that I would use the proper methods to seize the results, proving that flight attendance crews are capable of carrying on the proper techniques and information on how to proceed during emergencies. If results are not what expected, I would necessarily have to change the approach.