Instrument approaches in helicopters....?

fiveoboy01

fiveoboy01

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National Guard is based at my airport and so the Blackhawks fly in/out/around a lot.

The other day one asked for a practice ILS18(it was a vfr day).

This got me thinking. How is an instrument approach like an ILS flown any differently with a helicopter? Or, is it not?

When a helicopter has to hold, does it just hover? I know that sounds funny but i'm serious. Why would a holding pattern be flown if you can just sit in one spot?
 
Just like a fixed wing, no different. They fly holding patterns just like everyone else. Even have to comply with airspeed categories on the approach plates.

As a former enlisted crew chief, Ive got many hours in the back, trying to stay awake while pilots flew under the hood to maintain their proficiency.
 
Exactly the same as airplanes, except helicopters can reduce the visibility minimums by half but no less than 1/4 mile or 1200 RVR per 97.3 if they reduce the speed to 90 knots by the MAP

Helicopters also must fly approaches at 90 kts if using a COPTER approach
 
fiveoboy01 said:
National Guard is based at my airport and so the Blackhawks fly in/out/around a lot.

The other day one asked for a practice ILS18(it was a vfr day).

This got me thinking. How is an instrument approach like an ILS flown any differently with a helicopter? Or, is it not?

When a helicopter has to hold, does it just hover? I know that sounds funny but i'm serious. Why would a holding pattern be flown if you can just sit in one spot?
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I'll answer in general helicopter terms since I don't know the series Black Hawk in question. If it were a M model Black Hawk, they probably were letting the auto pilot fly it anyway. :)

Not sure if you're familiar with the controls on a helo but you've got a collective on the left which "collectively" changes the angle of incidence of the blades to go up and down. The cyclic or stick directs the thrust of the rotor and the anti torque pedals adjust yaw.

So, while doing an ILS, once you intercept the GS, you reduce collective to maintain on GS and basically adjust pitch with the cyclic to maintain speed. Say 100 kts indicated, for a Black Hawk you'd be looking at essentially a level attitude. The anti torque pedals act just as a rudder in a plane to keep the aircraft in trim.

Holding is done just like an airplane. You don't hover in holding. You'd use far too much power & gas and if you're IMC, a good way to get disoriented.

Really the main differences with RW vs FW are the type of approaches available and the increased IFR certification requirements (Part 27/29). In RW they have special "copter approaches" that have steeper descent angles and slower speeds. You also have "point in space" approaches to helipads. You can reduce vis cat A by half (no less than 1/4 mile) with helos as well.

Instruments are generally similar to FW but a slightly slower speed.
 
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I assume they have the capability, whether or not it's legal or smart(he said they burn a lot of fuel) is another story.

I flew RC helicopters a lot. I kind of know how they work... but I doubt my skills would transfer to the real thing other than knowing what the controls do and where they are:)
 
coloradobluesky said:
I don't think helicopters can hover in IMC, can they?
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Like brownout / whiteout hover or enroute IMC? You could but not something you'd want to do for any extended period of time without some sort of "hover hold" feature.
 
fiveoboy01 said:
I assume they have the capability, whether or not it's legal or smart(he said they burn a lot of fuel) is another story.

I flew RC helicopters a lot. I kind of know how they work... but I doubt my skills would transfer to the real thing other than knowing what the controls do and where they are:)
Click to expand...

Just to give you an idea on the difference with forward flight in holding vs hovering in holding.

A Black Hawk holding at 2,000 PA and 10 C and 100 KIAS will burn around 825 lbs / hr while pulling only 44 % torque. If they were to hold at a hover, they'd burn around 1075 lbs / hr and pulling 70 % torque. Much more efficient in forward flight, especially if you go to max endurance (760 lbs / hr).
 
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