How to most likely get a flight that will go above 40,000 ft?

Question

I wonder if there are passenger flights that would reach cruise altitudes higher than 40,000 ft (i.e. reach 41,000 ft for instance) more likely than others. It also depends on the plane of course, but assuming one gets a plane that can fly higher than 40k ft, e.g. the B777 or the B787 Dreamliner, are there other factors contributing to the likelihood of flying at higher altitudes?

The highest I think I've ever been is 38,000 ft, this was on a flight from Djerba to Central Europe in a B737 I think, but I'm unsure whether I didn't reach 39,000 ft on a transatlantic flight once in a B747 (it's too long ago to remember well). Then I've flown on many flights where there weren't those onboard screens where you can read altitude, speed and temperature but the captain announces the cruise altitude sometimes. However, I'm quite sure I've never flown above 40k ft (12.2 km). Are north-south flights more likely to fly at higher altitudes than west-east flights and/or are there other factors that may contribute to flying higher?

Edit: Following the revelations here I'm now sure that the flight from Djerba reached FL370, not 380 (it went slightly eastwards), and the transatlantic flight which was westwards to America probably reached FL380. So 38,000 ft MSL is really the highest I've ever been unless I don't remember correctly or haven't looked on a screen while a plane was higher or have been higher in some flight without those onboard screens and without the captain mentioning the cruise altitude.

Answer 1

Within the US, the recipe would be something along these lines:

• Eastbound
  • Since FL 410 is an eastbound altitude
• Moderately short, 1-2 hours - not so short that climbing high isn't worth it, nor so long that the aircraft takes off so heavy with fuel that 410 can only happen as a step-climb
• An aircraft that can reach 410
  • For example, a 737 NG or Max or a 777
  • Not an A-320 nor most regional jets
  • Ideally, for 737s, a 737-700, since this is a lighter airframe than the longer -800 or -900
• Light load of passengers
  • If total aircraft weight is high, the highest altitudes are unachievable, so a 737-700 that is half full can go higher sooner than a full one
  • An early morning or late night flight may be the best place to start looking for a light load; a mid-day flight in a popular market is more likely to be full (or close to it)
• Smooth air at 410
  • Examples of things to avoid here would be crossing the Rocky Mountains, especially the front range, especially with high winds (i.e. winter months), or crossing a major frontal boundary
  • Mountain wave becomes a problem when the airspeed variation it causes outstrips the performance of the aircraft to compensate, and performance is reduced at high altitudes.

Unless you're looking specifically to book a flight for the purpose of getting to 410, a lot of these factors are pretty "luck of the draw," but these things tend to be pretty common among the flights that do go that high.