Final Question #7 - interpretation of "both directions"

It’s a subtle issue, but, I’m assuming (“hoping”) that the question is not trying to ask for carriers that operate in both directions, but carriers that operate in “either” direction.
After playing with possible answers, I think (again: “hope”) I properly determined that the data doesn’t support an interpretation that the carrier must have flights on both legs of JFK to LHR and LHR to JFK.

text from question:
“Problem: Using the air_alliances and air_routes collections, find which alliance has the most unique carriers(airlines) operating between the airports JFK and LHR , in both directions.”

If I’m correct, the question would be better worded as “…operating between the airports JFK and LHR, in either direction.”

But the first sentence in the problem does say “in both directions”. English can be vague and the comma after LHR should not be there.

Why are you hoping that they intended “in either direction”?


The number of carriers flying in both directions (directly from JFK to LHR and also directly from LHR to JFK) between those two cities doesn’t seem to make sense relative to available answers. The question does not use the words “direct” or “indirect” to indicate whether an indirect route (e.g., hops that eventually connect to these cities) need be considered. I would hope that if the question writers wanted us to explore indirect paths between these cities they would have been explicit. Otherwise, the wording of this question can lead to too many interpretations for a final course question.

I agree that indirect routes was not indicated. That should be clarified but I have assumed that only direct routes should be considered.

Lets assume only direct routes until the TA’s clarify. I did find one of the available answers that made sense limiting to only those carriers that fly in both directions and only directly. In other words, the carrier is counted if it has at least one direct flight from JFK to LHR and at least one direct flight from LHR to JFK.



Yes, you’re correct. The intention is to find carriers that operate either from JFK-LHR or LHR-JFK. If there is an airline that operates in only one direction, and that airline is in a alliance, then it would be counted as a unique carrier for that alliance.

Can you also clarify we should include airlines that can only make the trip in several hops? Thanks.


No. Direct LHR-JFK or JFK-LHR only.