Approach Angles

[Redgrave_wrx]

Hey, everyone!

 

I am wondering if anyone has some good tips or advice for judging and picking your approach angles? I know you're supposed to have a sight picture of your pad and it shouldn't move up or down, but how do you determine where it should be?

 

I am having difficulty maintaining it to the ground and messing up on short final.

 

Any help would be appreciated.

 

Thanks!

[Wally]

Hey, everyone!

 

I am wondering if anyone has some good tips or advice for judging and picking your approach angles? I know you're supposed to have a sight picture of your pad and it shouldn't move up or down, but how do you determine where it should be?

 

I am having difficulty maintaining it to the ground and messing up on short final.

 

Any help would be appreciated.

 

Thanks!

 

Maintaining a constant approach angle to a stationary touchdown at a specific point is tough. I cheated in flight school, maintained a stationary point on the bubble until 300' agl and then counted back one stage field lane pad at a time through the decel. You probably don't have 7 equally spaced pads to a lane, so you'll have to cheat even more...

 

The 300 foot rule only works for a 10 deg glide path. Steep approaches will start moving down the bubble higher and shallow approaches will be lower agl. Try to set your decel on the glide to be a constant pitch up to decel to less than ETL at the point you start judging rate of closure externally (fast walk, whatever), then slow as possible to the hover or ground. Constant pitch up attitude makes you adjust slope with power, makes you think ahead, which is the whole point in training to a defined standard, but keeps you oriented to POWER.

 

In the real world, shallow makes a minimum, fixed power stationary touchdown easier for the patient pilot and harder for everybody else. The priority is safety, sometimes driven by obstacle clearance, sometimes by keeping the LZ in sight, which drive me to steep approaches.

 

I almost never do, er- DID a school approach (retired). Everything outside of a cruise is flown to have a survivable option, be it a forced landing, an abort, clearing obstacles, or power to the ground and out. High overhead, curving, sideward and stair-stepped approaches as required, but always flown attitude controlling speed/closure and power holding angle.

Edited September 7, 2016 by Wally

[Guest pokey]

any approach angle that gets you to the landing zone, while clearing all obstacles & doesn't involve the cops? works for me. Oh, one last important point: being able to fly the aircraft again without undue repairs. (and the 'bug says i never have anything useful to contribute?) now, did i tell ya about the time, my 7,,,,,,,,,,,,,,,,,

[r22butters]

During my training days I generally ended up short of my LZ, so I started aiming past it,...problem solved.

[brackac]

Thank god for fat bob.

[Hand_Grenade_Pilot]

Generally speaking, for your sight picture; with a shallow approach angle your spot will slightly below the center of the windscreen. Steep approach; spot is in the chin bubble. Normal angle, split the difference between the two. The specific sight picture depends on pilot height and cockpit design, as time goes on you'll develop an eye for it.

 

Your approach angle is dictated by obstacle clearance and performance requirements. In a performance limited situation (high weight or DA), you will want to maintain a shallow to normal angle in order to maintain enough airspeed to stay above ETL until you are entering ground effect. Another factor is your headwind component; landing into the wind (above 10kts or so) can keep you above ETL even on a steep approach.

 

Tall obstacles on final will obviously require you to maintain a steeper angle, which can result in you losing ETL and requiring additional power to maintain a stable rate of descent. When setting up for a steep approach where you anticipate loosing ETL, it is a good idea to 'load the disk' early in the approach (decelerating below ETL while simultaneously increasing power to maintain a stable decent). Doing so allows you to check your power reserve prior to being committed to the landing. It also prevent a large power change at the bottom of the approach which can result in sudden yaw movement and possibly an over torque / over temp event.

 

For maintaining a consistent approach angle, it is important to maintain the correct rate of closure (how fast you are moving toward your spot). Newer pilots have a tendency to come is fast and chase the approach angle by dumping the collective. Give yourself some extra time to slow down in anticipation of when you'll begin your descent. With the correct closure speed, you won't have to chase the angle. For a normal approach, your rate of closure should feel like a walking pace. Shallow approaches will feel like a brisk walk pace. On a steep approach, it should feel very slow. If you're approach feels rushed, just slow down a bit w/ the cyclic and be prepared to bring in a little extra power w/ the collective.

 

Also keep in mind that you have the ability to sidestep into a landing spot. Meaning that you can keep the helicopter lined up with the wind to maintain stability, while flying sideways towards the landing spot. This technique is very useful when you are dealing with stronger winds and obstacles prevent a straight in final to your spot.