Thursday, October 29, 2026 · Captain's Challenge
The Captain's Challenge.
Every evening, a harder question from the commercial, instrument and airline-level written exams. Only the best get this one. Each one answered, explained and cited, free. Tap your answer to see how you did.
This is a past question.The latest question
Capt. Mike: Here's that evening's Captain's Challenge. Tap your answer.
Which of the following statements CORRECTLY distinguishes the polar jet stream from the subtropical jet stream in the context of Canadian IATRA operations?
The answer
4The polar jet is variable in latitude and lower (FL 250-350); the subtropical jet is stable and higher (FL 350-400)
Explanation
The polar jet is highly variable latitudinally (can extend from 30°N to 60°N or higher), found typically at FL 250–FL 350 near the polar tropopause, and is responsible for the most severe CAT in the mid-latitudes — particularly relevant to Canadian operations year-round. It is strongest in winter when the temperature gradient between polar and tropical air is steepest. The subtropical jet is more stable in latitude (~25°N–35°N) and found at higher altitude (FL 350–FL 400) near the tropical tropopause. It is associated with less intense but still operationally significant CAT, and is relevant to Canadian operations on trans-Pacific and Caribbean routes.
Memory tip: Polar jet: **variable**, **lower** (FL 250–350), **strongest in winter**. Subtropical: **stable**, **higher** (FL 350–400), **always there**.
Source
Air Command Weather Manual (TP 9352E), jet streams (referred to by TC AIM AIR 2.10)
Taught in: IATRA › Advanced MeteorologyThis question is from the IATRA course, which teaches every IATRA subject and drills it like this. Unlock all 6 chapters with their quizzes (90 questions), and 6 full-length IATRA mock exams.
$99 CAD one-time · 3 months' access · no subscription
TC Exam Prep is independent and not affiliated with Transport Canada. The question and its explanation are ours. New questions go up every day: the warm-up at 9 am and the Captain's Challenge at 6 pm Pacific time.