Translation:I plan to go to Canada this year.
The implication of つもりだ is less certain than that, though. (Partly for cultural reasons-- getting a Japanese person to say something straight can be like pulling teeth, because culturally it's just not really done most of the time. Amd that's reflected in the grammar). But still, "I'm going to" implies a great degree of certainty and confidence. 行くつもり is more like, "(God willing/assumimg nothing comes up,) I plan/intend/hope to go." If it wdfe actually "I'm going" then they'd say 行きます unless they were being deferential at work or something.
~tsumori also doesn't necessarily imply that any preparations have already been completed. The flights may or may not be booked. The hotels may or may not be reserved. The time off request might have been submitted or processed, and they've probably LOOKED at flights and hotels, but that's all we can say for sure as a listener. But when we say "I'm going to," it implies that it's very much set in stone (unforseen disasters aside), and we wouldn't even use that conjugation unless hotels or flights were booked (one or the other at least). That's why we ofteb hear, "~するつもりだったが..." (I had intended to~ but...(something came up)."
[Disclaimer: I don't remember what text books have to say on this anymore, but this is how the real Japanese native speakers around me seem to be using this construction in real life].
(Some text books just explain the usage, others try and imply all sorts of cultural stuff. I'm just a translator, not a historical linguist, so I look for the shortcuts that always apply and simplify the way of thinking about things — and this one's pretty much "I intend to", and seriously speaking, you can lossy-imply it or spell it out in either English or Japanese, like you could say "I would have gone to Canada this year, but something came up"; this is not a difference of languages per se.)
I put 'I plan to' for one sentence but it was marked wrong with the translation given as 'I'm planning to'. the next time a similar sentence came up, I put 'I'm planning to' and it was marked wrong with the translation given as 'I plan to'. One was for 'next year' and one was for 'this year' but this should not make a difference in the translation of "tsumori".
I think the reason it wasn't included is tied to how the future tense is taught in Japan. At the junior high school level "be going to" is taught as つもり (tsumori) or 予定 (yotei). "Will" is taught as でしょう (deshou) and is mainly used for predicting the weather. I know the curriculum has been changing, but there's this kind of rigidity where "will" and "be going to" have to be separated and couldn't possibly be used to translate the same sentence.
[Edit to say this issue has been resolved and both "will" and "be going to" are accepted for future tense questions when we submit error reports.]
2020.5.19 I think some grammar books distinguish the difference between "will" and "be going to." Although most of the time it can be used interchangeably, some books insist that "will" also has a "not previously planned" future nuance.
The elevators at work are down. I will take the stairs instead.
I am going to go fishing this weekend.
I will go fishing this weekend.
are virtually interchangeable