Run-On Landing to Avoid Brown-Out?

Was this really the best decision?

Although I don’t usually comment on accident reports until the Probable Cause is released, this one seems pretty cut-and-dried. It’s also a good discussion topic. And, best of all, no one was hurt — which also leads me to believe that there won’t be many more facts about it published.

Here’s what happened:

The pilot and the border patrol agent had been dispatched to provide aerial support for an on-going border patrol mission. When the pilot realized there would be a delay in time for when they needed to engage in the mission he decided to land in a grass field and sit idle (to conserve fuel) until their assistance was needed. He said he made a run-on landing to avoid creating a brown-out condition. However, as the helicopter touched down and moved forward (approximately 34 feet) it nosed over and the main rotor blades struck the ground. The helicopter subsequently nosed over and traveled another 34 feet before it came to rest on its right side.

I question the decision to do a run-on landing on dirt/grass. (I suspect the pilot is also rethinking that decision right now.) Would it really reduce the amount of dust blown around enough to justify the added risk of forward motion in contact with the ground on a rough surface?

Brown-Out Landing
Military photo by Staff Sgt. Christopher Boitz of a HH-60G Pave Hawk doing a brown-out landing. (A run-on landing would probably be a piece of cake with wheels.)

I’ve landed [too] many times in dusty landing zones. The dust starts to rise about when I get into ground effect. The longer I’m above the ground pulling pitch, the more dust flies — unless it’s just surface dust and not really deep. The key, it seems, is to get the collective full-down as quickly as possible. When you stop pulling pitch, the dust settles.

When I was trained to do run-on landings, I was taught to make a shallow approach at a speed right around ETL and then slowly lower the collective once contact with the ground was made. So not only is pitch pulled during that shallow approach — when you’re close enough to get the dust flying — but it’s not full down for at least a few seconds after making contact. I can’t see how that would reduce the amount of dust on landing. I’ll be the first to admit that I haven’t tested this theory — we always practiced run-on landings on pavement — perhaps a reader can offer some insight from experience?

I’m thinking that a better way to handle this particular landing would be to make a straight in approach to the ground, thus minimizing the amount of time you’re pulling pitch while in ground effect. It would be important to assure that the touchdown spot was appropriate before committing. Then fly it right to the ground and dump the collective as soon as you’re on the ground. This is the way I try to handle my dusty LZ landings, usually to avoid kicking up dust around spectators or taking even more paint off my rotor blades. (Dust is nasty shit; I’ve already had my main rotor blades painted twice in 1,350 hours.) I admit I’ve never landed on dust so thick that true brown-out was possible — although I’ve come pretty close a few times.

What do you think? How would you handle landing at a LZ where brown-out was possible?

4 thoughts on “Run-On Landing to Avoid Brown-Out?

  1. I fly quickly to the spot maintaining the approach speed and decent angle to arrive at a stopped point as I contact the ground. Granted I’m flying pretty light piston machines that produce much less rotorwash compared to a blackhawk or such but I believe the principle applies the same. You do not want to terminate to a hover and decend. Usually you’ll be close to brownout about the last 2 seconds before you touch the ground so focus on the ground immediately in front of you as you slow to your predetermined spot.

    • That’s something I hadn’t considered: weight of the aircraft. I wonder how much of a difference that makes in landing technique, just in general. The largest thing I ever flew was a Long Ranger, so my experience is limited.

  2. First a disclaimer, I have not landed in dusty conditions. Most of my flying has been done over pavement or grass fields. So my thoughts are more theoretical than practical.

    That said, during my training the technique described by apiaguy was the method presented and practiced. I was told part of why that works is that you’re moving forward and the dust cloud is behind you allowing you to see what’s out front. And part of why it works is you get the collective down faster which stops making more dust.

    For takeoff you should take off directly from the ground instead of pulling the helicopter up into a hover and then transitioning to forward flight. This does require the pilot to be VERY careful that the landing gear is not stuck to the ground.

    The same techniques were also recommended for winter operations to avoid white outs from flying snow. Again you need to be especially careful that the gear isn’t frozen to the ground when trying a direct takeoff from the ground.

    The border patrol pilot might have thought he could achieve the same results with the run on landing. Keep moving forward, keep the dust storm behind him. I would speculate that the post landing nose over could have been from: lowering the collective too fast, slamming on the brakes, running into a hole or obstruction with the wheels (think dynamic roll over but forward instead of sideways) or some combination of the above.

  3. If your helicopter permits this (I fly a AW109S with HEMS configuration, about 3100 kg operative weight) I suggest to stop in a high quite OGE hovering and, going down slowly, vertically, “test” the brownout sprading away and “clean” the area.
    The brownout will form a rounded cloud flying away, you will go down, vertically, inside the clean tube formed by the downwash and having in sight a reference (it’s quite impossible there will not be a stone or something similar anchored to the ground).

What do you think?