Landing Zone Considerations For Helicopter Operations


CarolinaFireJournal - Bob Twomey
Bob Twomey
07/16/2019 -

It has been a while since I reviewed proper considerations for selecting and setting up helicopter landing areas, otherwise known as landing zones (LZs), for helicopters serving your service areas. 

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Mowed hayfield is excellent for a helicopter landing zone.

It has been my observations, both as a rescuer and a helicopter pilot, that many departments don’t take seriously the basic concepts of selecting and setting up an LZ for an inbound helicopter.

While it is true that the pilot in command (PIC) of an inbound helicopter has the final authority to land in an LZ, it is also true that quality, basic information relayed to the pilot can greatly enhance the overall safety of the mission for the aircrew and the people on the ground. After all, we as rescuers strive to exercise safety in our rescue and medical operations, so why not in our LZ operations?

When in flight school, the 6 Ss and the 2 Ws were drilled into us students for safer landings; we recalled it as “SSSSSSW2” while performing a helicopter landing. The above acronym stands for: Size, Shape, Surface, Slope, Surroundings, Sun, Wind Direction and Speed.

SIZE

The Technical Rescue Standard (TR certification) states that, at a minimum, a helicopter LZ should be 100 ft. x 100 ft., which is a little less than one half of an acre. If you have ever been on a helicopter approaching a one-half acre LZ, it’s like landing on a postage stamp! While pilots make the landing look easy, there are MANY things that can go wrong while landing into a small LZ in a remote area. A steep approach on a hot, humid summer day with a high-density altitude and at a high land elevation, with fuel and payload and crew weight, and slow approach speed, can lead to some very serious consequences — really fast.

Without going into all the technical stuff about why and how this can be dangerous, just keep this thought in mind — select an LZ as large as possible. The bigger the LZ, the more safety options the pilot has IF something goes wrong during the approach for landing and during take-off. It will not always be possible to have a bigger LZ, but remember, you’re asking a pilot to land the helicopter and crew into a confined space, without much “wiggle room.”

SHAPE

An LZ’s shape is generally dictated by the topography and surrounding obstacles, such as trees or powerlines. A pilot needs to hear from the LZ manager about the shape of the LZ relative to surrounding obstacles and wind speed and direction. Generally speaking, a “longer” LZ, as in a rectangular shape rather than a square or a circle, can be more advantageous to a pilot upon approach and take-off. This allows for a reduced angle of approach and a bit more forward airspeed upon landing. Upon take-off, it can allow for more attained speed and less steep of a departure angle, which are beneficial to the rotor efficiency — and therefore, safety.

SURFACE

The surface of the selected land zone is important. Is it sandy, gravelly, bare soil, or is it grassed, concrete (any hard surface) or snow/ice covered? Sandy, gravelly or dusty LZs tend to create large dust clouds from the rotor wash and kick up debris which can sandblast the leading edges of the spinning rotor blades and be ingested into the engine air intakes. Likewise, large dust clouds or snow blown up around the helicopter can blind the pilot, causing a loss of visual contact with the ground. This is called spatial disorientation and can be extremely dangerous.

If the LZ is dusty, quickly hose it down with the charged line you will have ready for the helicopter landing. This will reduce blowing dust and debris from the rotor wash while landing. If the LZ has tall grass, as in a hayfield, let the pilot know this, as hovering over tall grass requires more power. Also, tall grass can hide obstacles, like rocks and stumps, which can damage the landing gear upon landing. Let the pilot know that you have checked the LZ for foreign objects and debris (FOD) (rocks, roots, stumps, limbs, etc.) so that he/she knows it is safe to land. Keep in mind that tall grass and weeds can be a fire hazard around helicopters.

Example of numerous hazards around this rural landing zone — barn, trees, fences, livestock, possible overhead powerline to barn.

If your LZ has ice on it, mainly for a paved surface, this can cause the helicopter, once it has landed, to slide on the surface, especially if there is a slope on the LZ. All helicopters have vibration; vibration on a slick surface can sometimes allow the helicopter to slide. Giving the pilot the surface type and slope of the LZ before the time of landing can give them valuable insight as to whether to land or seek an alternative LZ.

SLOPE

All helicopters can land on a certain degree of slope. All helicopters have limits as to how much slope is allowable for landing. Slope landings require a high degree of skill. Different landing methods are required depending on if the slope is parallel or perpendicular to the airframe. In general, the LZ slope should not exceed 10 percent (or 1.0 ft. drop in 10 ft.). The rule is:  the flatter the slope, the safer the landing. You can see here that slope, combined with surface type, can be valuable information to a pilot.

SURROUNDS

“Surrounds” deals with informing the pilot of any hazards around the LZ and in the approach path. This can include trees, powerlines, elevated wires or ropes, flagpoles, vehicles, livestock, fences — basically anything that presents a clear and present danger to the aircraft upon contact. Especially in the summer months or when foliage is prominent, wires and powerlines are very difficult to see from the air. Pilots generally assume wires to be present along any roadway. It is prudent for any helicopter pilot to assume wires can be anywhere near an LZ until proven otherwise. As the LZ coordinator, it is your responsibility to be absolutely positive that no obstruction exists between the helicopter and the intended touchdown area. IF obstructions are present, you MUST inform the pilot about them, such as type of obstruction, height of the obstruction, where the obstruction(s) is relative to the LZ (as in north, south, east or west of the LZ and how far from the touchdown area). Then the pilot can make a better-informed decision whether to attempt a landing or not.

This landing zone is longer than wider adding safety to approaches and take-offs.

At night, this information is even more critical, even though nearly all air medical helicopters fly with night vision capabilities. However, night vision devices still may not “see” all hazards present. Now obviously some common sense must be utilized in describing your intended LZ. If you know the wind direction and estimated speed, you know that most pilots, given the opportunity, prefer to land into the wind. This due to the beneficial effects of a headwind when operating low and slow to the ground. Light winds, five to 10 knots are not usually a problem to land in with a crosswind or tailwind relative to the touchdown area, but you should still provide this information to the pilot so he/she can decide upon their best approach. The final decision will ALWAYS be up to the pilot.

SUN

How many times have you ever been driving in a westerly direction with the sun shining directly into your eyes and providing glare on your windshield? When looking directly or almost directly into the sun, it is very difficult to judge distance or see objects in front of you. Now, consider you are the pilot and you are flying close to the ground, unable to see what is in front of you due to glare and looking into the sun. Would you want to be in that situation? When possible, try to set up your LZ such that the pilot does not have to deal with what I call “glare blindness” upon final approach. Sometimes this won’t be possible, and the pilot may execute a crosswind approach, turning into the sun at the last possible moment in order to align with the LZ touchdown point.

WIND

When communicating with an inbound helicopter, you should provide the pilot with the wind direction and estimated speed. If there is no wind, simply advise the pilot that “present wind at your LZ is calm.” Give the pilot the direction the wind is coming from and your estimate of the windspeed. You can use miles per hour or knots (since 1 knot equals 1.1 mph). Pilots use knots in describing windspeed, but miles per hour is acceptable. No reason to pole vault over peanuts on this; just give the estimated speed as they circle for final approach.

So, there you have it, plain and simple — SSSSSSWdirection/speed.

Here is an example transmission to the pilot of your inbound helicopter. Let’s use “helicopter 20” as your air ambulance provider’s name:

“Helicopter 20, this is your LZ manager, how do you copy?”

“LZ, helicopter 20 copy you loud and clear, can you provide LZ information?”

“Affirmative helicopter 20. Your LZ is a two-acre rectangular pasture on the east side of the highway, no livestock present. The grass is approximately 12 inches high, firm flat surface. Obstructions are the tree line on the west side of the highway, fencing on all sides of the pasture, and a single powerline at the south end of the pasture, running east and west. Wind is out of the northwest at estimated eight knots, gusting to 15 knots. Helicopter 20, do you copy?”

“LZ helicopter 20, we copy and have you in sight and we are on final approach.”

So, is that plain enough? Absolutely! A clear, concise description of the LZ with all that the pilot needs to assist with a safe landing. You should be able to provide this information in 20 to 30 seconds. If the pilot requires additional information, he/she will ask for it. A critical note though: BE CORRECT IN YOUR DATA TO THE PILOT!

On another note, the “Helicopter Use in Search and Rescue Support” class that I have taught around the state for 23 years is no more. Those rescuers who wanted this class have, for the most part, taken it and earned their certificates accordingly. It was the most unique class of its type in North Carolina, going into great detail about many concepts of integrating helicopters into your SAR operations. Students actually flew simulated searches as part of the class. In past articles, I went into significant detail about how to integrate private helicopter resources into your programs, especially after natural disasters — floods, severe snow events, isolated victims, etc. I hope that some of you took advantage of that information. It has been a most rewarding program to teach. In short, it has been a good run.

Until next time, BE SAFE!

Bob Twomey has been in the volunteer rescue service for 46 years, having served on five Rescue Squads from the coast to the mountains. He is currently a member of Transylvania County Rescue Squad, past Chief and Training Chief, an EMT for 45 years, and is an IFSAC and OSFM certified Rescue Instructor. Bob has been active in SAR, Mountain Rescue, and teaches high-level rescue. He is the chief pilot of Wolf Tree Aviation, and flies helicopter searches and rescue support locally. He is a Crew Chief for the NC Forest Service. He can be reached at 828-884-7174 or at [email protected]
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Issue 34.1 | Summer 2019

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