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Hello all!

I flew yesterday with another pilot, and as usually happens we had a difference of opinion on technique. I was always taught to climb out at Vy unless there is a specific reason to use Vx (obstacles, terrain, etc.). My companion for the day was taught to climb out slower, just above Vx. We were in a 127M, Vx is 64 KIAS, Vy is 78 KIAS. My main reasoning for always using Vy is to have the extra airspeed for maneuvering if necessary. His reasoning was to always get as high as possible as close to the airport as possible.

Do any of the CFIs out there have any thoughts on the matter?

Thanks!
Mark

i usually teach Vx until any obstacles ahead are cleared and then Vy for better cooling, visibility etc. But I cant come up with a really great argument against climbing for maximum altitude over distance, unless it will overheat the cylinder heads.

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Everyone must believe in something, I believe that I will go flying.

I think it's a matter of pilot preference and intent for that portion of the flight. I have seen both taught, and typically teach Vy climb out unless obstacle clearance is required.
If your only objective is to clear an obstacle and gain greatest altitude for a given distance, then absolutely, Vx is your speed.

However, I fly in an area of high traffic and in airplanes in a fleet that need some care...my overall is performance over a longer distance and so all these add up to Vy being a better speed.

I think what's important is that you have thought about what you are trying to accomplish and choose a performance speed that matches that.

Interesting. Is the objective to be at an altitude where if u had an engine failure, you would be able to glide back to the field?

If so then who's to say Vy might not be better?
Let's think about this. Vy gives you best height in a given time. So let's say for the sake of argument that Vx gives you 500fpm and Vy gives you 700fpm.
Scenario: you take off and have an engine failure 1 min after take off.

At Vx you are 500' agl, at Vy you are 700'
Which height would you rather be at?

Climbing at Vy you would be further from the field, but higher.
At 700' you could make an attempt to turn back to the field
At 500' you cannot.
Climbing at Vx at 500' - engine failure - you are AT you best glide speed in a 172M 65 kts, you must lower the nose immediately. You are now descending.
Climbing at Vy at 700' you can hold altitude a little longer as your speed reduces from 78 to 65kts.

To measure this ability to get back to the field you would need to have climb gradients for Vx & Vy to see if the extra height gained using Vy (200') would glide you the extra distance required.
That I dont know and would welcome comments on this.

When it comes to engine failure, height is priceless. It gives you more time to assess options, trouble shoot, possible solve the issue and so on.

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Fly safe,

David

Wow, thanks for the great input everyone! David, I hadn't even thought of the extra altitude aspect.

Regards,
Mark