question: what kind of aircraft is used on the first class american airlines flight from philadelphia to san francisco with a dallas stopover 
#1 return flights 
#2 return #1 on  american airlines 
#3 return #2 that  is  first class 
#4 return #3 from  philadelphia 
#5 return #4 to san francisco 
#6 return #5 with  a dallas stopover 
#7 return kind of aircraft used on  #6