Approach angles

[NickLappos]

bladewashout,
Remember the joke about the little boy who blew a small horn every minute. When asked why, he said "It keeps the elephants away." When told there were no elephants within 100 miles, he said, "See, it works!"

To make an approach and at the bottom be much less than 300 fpm is good pilotage, and likely to produce a very satisfactory approach. I used to tell students that at 100 feet they better be at 300fpm or less, or I would start yelling, even in a three engined monster with 13,000 horsepower. Nothing to do with VRS, it is because it keeps the elephants away.

Regarding descending vertically, if you are in a helo with barely the power to hover IGE, who wants to try and hover OGE? You will fall like a rock, hit the ground and say "VRS!" and we will all nod sagely. Meanwhile, US Army attack helicopters fly profiles where they hover OGE to shoot over a ridgeline, bob back down, straight down, at 300 to 500 fpm, stop quickly in space and move laterally to the next fire point. I guess VRS is against Army regs, or perhaps these helos have 10% power margin while HOGE.

I even saw a poster above who was worried about pulling in power while at low speed in a descent, as if the power pull would CAUSE the VRS! The misunderstanding about the low speed portion of our envelope is aweful, and the old guides and sage advice from practical but (forgive me) slightly misinformed instructors does not help.

There are great reasons not to descend vertically in underpowered helos, but they are not VRS. Follow the advice about 300 fpm, as a limited case where underpowered helos must be babied, just don't take the aerodynamics to the bank. In a helo with enough power, that vertical region is a whole new degree of freedom. Ask photo chase pilots, folks who tend power lines, those who fly NOE for a living.

VRS is:

Caused when you descend vertically fast enough to start catching up with your downwash.

Never experienced at less than 50 to 75% of your downwash speed

Not at all likely to occur in any helo at 300 fpm

Often confused with "over pitching" or "hovering without proper power"

Grossly misunderstood by almost every old line instructor and training guide

Harder to experience at high altitude or high gross weight

Very very seldom the cause of any helo accident (see "over pitching" for the real reason, in most cases.

One of the best ways to kick off a good thread on pprune!

Regarding listening to your flight instructor, please remember your Mother told you to bundle up, so you don't catch a cold. She was off base (viruses do not care how cold you are!), but the advice was sound, and the intention was excellent!