Tag Archives: accident

Airport Tower Closures: Reality Check

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March 24, 2013, 11:30 AM Edit: Got the airplane terminology wrong. Thanks to two airplane pilots for correcting me. I’ve edited the text to show the change. Sorry about the confusion. – ML
March 25, 2013, 2:15 AM Edit: Left out the word towers in a sentence.

Come on folks — it’s not as bad as you think.

Falcon Tower
The control tower at Falcon Field Airport in Mesa, AZ is a typical Class Delta airport tower. (This is not one of the towers scheduled for closure.)

I’ve been reading a lot lately about the FAA’s upcoming airport tower closures. A list is out and there are 149 airports on it. The reduction of funding due to the sequester is making it necessary to close these contracted airport towers all over the country.

Most news articles, tweets, and Facebook updates that I’ve read about the closures are full of doom and gloom. Apparently, a lot of people believe that airport towers are required for safety. But as most general aviation pilots can attest, low traffic airports do not need towers.

What an ATC Tower Does

Air Traffic Control (ATC) towers are responsible for ensuring safe and orderly arrivals and departures of aircraft at an airport. Here’s how it works at a typical Class Delta airport — the kind of airports affected by the tower closures.

Most towered airports have a recording called an Automated Terminal Information System (ATIS) that broadcasts airport information such as weather conditions, runway in use, and any special notices (referred to as Notices to Airmen or NOTAMs). Pilots listen to this recording on a special airport frequency as they approach the airport so they’re already briefed on the most important information they’ll need for landing. The ATIS recording is usually updated hourly, about 5 to 10 minutes before the hour. Each new recording is identified with a letter from the ICAO Spelling Alphabet, or the Pilot’s Alphabet, as I refer to it in this blog post.

Before a pilot reaches the airport’s controlled airspace — usually within 4 to 6 miles of the airport — she calls the tower on the tower frequency. She provides the airport controller with several pieces of information: Aircraft identifier, aircraft location, aircraft intentions, acknowledgement that pilot has heard ATIS recording. A typical radio call from me to the tower at Falcon Field, where I flew just the other day, might sound something like this:

Falcon Tower, Helicopter Six-Three-Zero-Mike-Lima is eight miles north, request landing helipads with Kilo.

An airplane calling in might say something like:

Falcon Tower, Cessna One-Two-Three-Alpha-Bravo is ten miles east, request touch-and-go with Kilo.

Kilo, in both cases, is the identifier of the current ATIS recording.

The tower controller would respond to my call with something like:

Helicopter Six-Three-Zero-Mike-Lima, Falcon Tower, proceed inbound. Report 1 mile north for midfield crossing at nineteen hundred feet.

To the airplane, he might say something like:

Cessna One-Two-Three-Alpha-Bravo, Falcon Tower, enter right downwind for runway four right.

(If you want to see what these instructions mean by looking at a detailed airport diagram, here’s one for you.)

Of course, if the tower controllers were really busy or there was some sort of problem at the airport, the controller could say something like:

Aircraft calling Falcon Tower, remain clear of the class delta airspace.

That means the pilot can’t come into the airspace — which is marked on charts and many GPS models — until the tower clears her in. That happens very seldom.

This is the beginning of the conversation between the air traffic controller in the airport’s tower and the pilot. What follows is a dialog with the tower providing instructions and the pilot acknowledging those instructions and then following them. The controller’s job is to sequence airplane traffic on the airport’s runway(s), making sure there’s enough spacing between them for the various types of landings: touch-and-go, full stop, low approach, etc. In the case of helicopters — which is admittedly what I know best — the tower can either put us into the traffic pattern with the airplanes (which really isn’t a good idea) or keep us out of the airplane flow. The tower clears airplanes to land on the runway and gives permission to helicopters to land in “non-movement” areas.

At the same time all this is going on, the tower’s ground controller is providing instructions to airplanes that are taxiing around the airport, either to or from the runways. Aircraft are given taxi instructions that are sort of like driving directions. Because helicopters seldom talk to towers, I can’t give a perfect example, but instructions from the transient parking area to runway 4R might sound something like this:

Cessna One-Two-Three-Alpha-Romeo, Falcon Ground, taxi to runway four right via Delta. Position and hold Line up and wait at Delta One.

These instructions can get quite complex at some large airports with multiple runways and taxiways.

Position and hold Line up and wait — formerly hold short position and hold — means to move to the indicated position and do not cross the hold line painted on the tarmac. This keeps the airplane off the runway until cleared to take off.

A pilot who is holding short waiting switches to the tower frequency and, when he’s the first plane at the hold line, calls the tower to identify himself. The tower then clears him to get on the runway and depart in the direction he’s already told the ground controller that he wants to go.

Air traffic control for an airport also clears pilots that simply want to fly through the airspace. For example, if I want to fly from Wickenburg to Scottsdale, the most direct route takes me through Deer Valley’s airspace. I’d have to get clearance from the Deer Valley Tower to do so; I’d then be required to follow the tower’s instructions until the controller cut me loose, usually with the phrase “Frequency change approved.” I could then contact Scottsdale’s tower so I could enter that airspace and get permission to land.

A few things to note here:

  • Not all towers have access to radar services. That means they must make visual contact with all aircraft under their control. Even when radar is available, tower controllers make visual contact when aircraft are within their airspace.
  • If radar services are available, tower controllers can ask pilots to Ident. This means pushing a button on the aircraft’s transponder that makes the aircraft’s signal brighter on the radar screen, thus making it easier for the controller to distinguish from other aircraft in crowded airspace. The tower can also ask the pilot to squawk a certain number — this is a 4-digit code temporarily assigned to that aircraft on the radar screen.
  • Some towers have two tower controller frequencies, thus separating the airspace into two separately controlled areas. For example, Deer Valley Airport (DVT) has a north and south tower controller, each contacted on a different frequency. When I fly from the north over the top of the runways to land at the helipads on the south side, I’m told to change frequency from the north controller to the south controller.
  • The tower and ground controllers coordinate with each other, handing off aircraft as necessary.
  • The tower controllers also coordinate with controllers at other nearby airports and with “center” airports. For example, when I fly from Phoenix Gateway (IWA) to Chandler (CHD), the Chandler controller knows I’m coming because the Gateway controller has told him. Similarly, if a corporate jet departs Scottsdale (SDL) on an Instrument Flight Rules (IFR) flight plan, the Scottsdale controller obtains a clearance for that jet from Phoenix Departure or Albuquerque Center.

I should also point out two things from the point of view of a pilot:

  • Dealing with air traffic control does add a tiny bit to the pilot’s workload. The pilot must communicate with the tower before entering the airspace, the pilot must follow the tower’s instructions (unless following those instructions is not safe, of course). I know plenty of pilots who would rather fly around a towered airport’s airspace than fly through it — just because they don’t want to talk to a controller. I’ll admit that I’ve done this quite a few times — I even have a winding route through the Phoenix area between Wickenburg and Chandler that avoids all towered airspace along the way.
  • Air traffic control gives many pilots the impression that they are no longer responsible for seeing and avoiding other aircraft. After all, the tower sees all and guides aircraft to avoid each other. But there have been instances where air traffic control has dropped the ball — I experienced one myself years ago — and sometimes this can have tragic consequences.

Low Traffic Airports Don’t Need Towers

As you can probably imagine, the more air traffic coming and going in an airport’s airspace, the busier air traffic controllers are.

A very busy airport like Deer Valley, which has at least two flight schools, several helicopter bases (police and medevac), at least one charter operator, and a bit of traffic from corporate jets, can keep controllers pretty busy. In fact, one of the challenges of flying in and out of Deer Valley is being able to get a call in on the radio — it’s often a steady stream of pilot/controller communication. Indeed, Deer Valley airport was the 25th busiest airport in the country based on aircraft movements in 2010.

Likewise, at an airport that gets very little traffic, the tower staff doesn’t have much to do. And when you consider that there has to be at least two controllers on duty at all times — so one can relieve the other — that’s at least two people getting paid without a lot of work to do.

Although I don’t know every towered airport on the list, the ones I do know don’t get very much traffic at all.

For example, they’re closing four in Arizona:

  • Laughlin/Bullhead City International (IFP) gets very little traffic. It sits across the river from Laughlin, NV in one of the windiest locations I’ve ever flown into. Every time I fly into Laughlin, there’s only one or two pilots in the area — including me.
  • Glendale Municipal (GEU) should get a lot of traffic, but it doesn’t.
  • Phoenix Goodyear (GYR) is home of the Lufthansa training organization and a bunch of mothballed airliners, but it doesn’t get much traffic. Lufthansa pilots in training use other area airports, including Wickenburg, Buckeye, Gila Bend, Lake Havasu City, and Needles — ironically, none of those have a tower.
  • Ryan Field (in Tucson; RYN) is the only one of the three I haven’t flown into, so I can’t comment its traffic. But given the other airports on this list, I have to assume the traffic volume is low.

They’re also closing Southern California Logistics (VCV) in Victorville, CA. I’ve flown over that airport many times and have landed there once. Not much going on. It’s a last stop for many decommissioned airliners; there’s a 747 “chop shop” on the field.

They’re closing Northeast Florida Regional (SGJ) in St. Augustine, FL. That’s the little airport closest to where my mom lives. When she first moved there about 15 years ago, it didn’t even have a tower.

These are just the airports I know. Not very busy. I know plenty of non-towered airports that get more traffic than these.

How Airports without Towers Work

If an airport doesn’t have a tower — and at least 80% of the public airports in the United States don’t have towers — things work a little differently. Without a controller to direct them, pilots are responsible for using the airport in accordance with standard traffic patterns and right-of-way rules they are taught in training.

Some airports have Automated Weather Observation Systems (AWOS) or Automated Surface Observation Systems (ASOS) that broadcast current weather information on a certain frequency. Pilots can tune in to see what the wind, altimeter setting, and NOTAMs are for the airport.

When a pilot gets close to a non-towered airport, she should (but is not required to) make a position report that includes her location and intentions. For example, I might say:

Wickenburg Traffic, helicopter Six-Three-Zero-Mike-Lima is ten miles north, landing Wickenburg.

An airplane pilot might say:

Wickenburg Traffic, Cessna One-Two-Three-Alpha-Bravo is eight miles southeast. We’ll be crossing midfield at five thousand to enter right traffic for Runway Two-Three.

Other pilots in the area would hear that call and respond by making a similar position call. The calls continue as needed at the pilot’s discretion — the more aircraft in the area, the more calls I make just to make sure everyone else knows I’m out there and where I am. Pilots then see and avoid other traffic to land or depart the airport.

It sounds crazy, but it works — remarkably well. In Wickenburg, for example — an airport that gets a lot of pilots in training practicing takeoffs and landings — there might be two or three or even more airplanes in the traffic pattern around the airport, safely landing and departing in an organized manner. No controller.

And this is going on at small general aviation airports all over the country every single day.

What’s even more surprising to many people is that some regional airlines also land at non-towered airports. For example, Horizon operates flights between Seattle and Wenatchee, WA; Wenatchee is non-towered. Great Lakes operates between Phoenix or Denver and Page, AZ; Page is non-towered.

The Reality

My point is this: people unfamiliar with aviation think that a control tower is vital to safe airport operations. In reality, it’s not. Many, many aircraft operate safely at non-towered airports every day.

While the guidance of a tower controller can increase safety by providing instructions that manage air traffic flow, that guidance isn’t needed at all airports. It’s the busy airports — the ones with hundreds of operations every single day — that can truly benefit from air traffic control.

The 149 airport towers on the chopping block this year were apparently judged to be not busy enough.

I guess time will tell. And I’m certain of one thing: if there is any accident at one of these 149 airports after the tower is shut down, we’ll hear about it all over the news.

In the meantime, I’d love to get some feedback from pilots about this. Share your thoughts in the comments from this post.

Inappropriate Solo Training Landing Zone?

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How about preventing accidents by making conditions easier for new pilots?

I stumbled across this brief preliminary accident report in the NTSB database today. Here it is in its entirety:

The pilot who held a commercial pilot certificate with single-engine land airplane ratings was receiving training to obtain a helicopter rating. The pilot had 31 hours of helicopter flight time and the accident occurred on his second solo flight. The pilot reported he was attempting to takeoff from a wet grass area when the accident occurred. He stated that when he increased the collective to lift off, the helicopter began to roll to the right with the right skid still on the ground. He moved the cyclic to the left and the helicopter responded by rolling to the left with the left skid contacting the ground. The pilot then applied right cyclic and the helicopter again rolled to the right. The right skid contacted the ground and the helicopter rolled over onto it’s right side. As a result of the accident, the main rotor blades and the helicopter fuselage were substantially damaged. The pilot reported that there were no preimpact mechanical failures/malfunctions that would have precluded normal operation.

The accident aircraft was a 2003 Robinson R44 Raven II.

Those of us who have soloed in Robinson (or other small) helicopters know that balance varies greatly depending on how many people are on board. We learn to fly helicopters with two people on board: student pilot and instructor. The helicopter is usually quite balanced with two people on board. I don’t have the exact numbers for this particular flight, but using my R44 as a guide and assuming the pilot and instructor were each 200 pounds with 1/2 tanks of fuel, the weight and balance envelopes should look something like this:

W&B with 2 On Board

If you’ve never seen one of these, let me explain. The longitudinal weight and balance chart shows where the weight is distributed front to back. The pink line represents the main rotor mast. With two 200-pound people on board in the front seat, the center of gravity is forward of the mast. This is pretty normal for an R44. The lateral weight and balance chart, which is what we’re more concerned with in this analysis, shows how the weight is distributed side to side. The 0.00 mark is dead center and, as you can see, the with/without fuel points are very close to the center. In other words, it’s laterally quite balanced.

Now take the instructor out of the left seat. With everything else remaining equal, here’s what the weight and balance envelopes look like:

W&B with 1 on board

First of all, the center of gravity shifts aft. That makes a lot of sense. After all, there’s 200 pounds less weight up front. When I fly, this is extremely noticeable, especially at my new, slimmer weight. The helicopter actually lands on the rear of its skids first; on pick up, the front of the skids come off the ground first.

Laterally, there’s also a big change — and again, that’s what we need to focus on here. Without that 200 pounds of weight on the left side of the aircraft, the center of gravity shifts quite a bit to the right. The heavier the pilot is, the more to the right the weight shifts. So although I used 200 pounds in my example, if the pilot was 250 pounds — which is still legal in an R44 — the weight would shift even further to the right (and slightly forward). When the pilot attempted to lift off, the left skid would rise first.

Again, I don’t have the exact numbers. You can play with this using any reasonable numbers you want. It won’t change the conclusion here.

Now read the description of the accident events and put yourself into the pilot’s seat. He’s taking off so he’s lifting the collective slowly, getting the helicopter light on its skids. The left skid comes off the ground first because that side of the aircraft is lighter. This feels to the pilot as if the helicopter is rolling to the right while the right skid is still on the ground.

Stop right there. This is where the terrain comes into the picture.

The pilot is on wet grass. The accident report didn’t say mud so we won’t assume a sticky surface. But it certainly isn’t smooth. We don’t know how long the grass is or whether it’s uniform or has clumps of thick weeds. The question we should be asking is this: was the right skid “stuck” and creating a pivot point? The answer to that question determines the appropriate action:

  • If the right skid is indeed “stuck” and creating a pivot point, the correct action to avoid dynamic rollover would be to lower the collective. In other words, abort the pick up.
  • If the right skid was not “stuck” or creating a pivot point, the correct action would be to adjust the cyclic to assure there was no lateral movement (as you’d normally do in a pick up) and continue raising the collective.

An experienced pilot would know this. An experienced pilot would have done dozens or hundreds or thousands of solo pickups. He’d have a feel for the aircraft or, at least an idea of what to expect and what to do.

But this wasn’t an experienced pilot. It was a student pilot with only 31 hours of flight time — almost all of which was with a flight instructor beside him — on his second solo flight. So he used the cyclic to stop what he perceived as a roll. He may have been more aggressive than he needed to be, thus causing the helicopter to come down on the left skid. Then another adjustment to the right. The right skid hits that grassy surface and the helicopter rolls. Game over.

So my question is: What the hell was he doing taking off and landing on wet grass?

Flight instructors can reduce the chances of accidents like this by setting up their student pilot solo flights with easy flight conditions. That includes smooth surfaces for takeoff and landing. If this had happened on a nicely paved airport ramp or helipad that was free of surface obstructions like cracks or tie-downs, this accident may not have happened at all. There would be no question about a pivot point because none could exist.

You might also question whether the flight instructor properly taught the concept of dynamic rollover and what to do if it’s suspected on takeoff — lower the collective. And whether the flight instructor made it clear that there should be no lateral movement on pick up or set down. Yes, I know that’s hard for a new pilot to do — especially with only 31 hours — but it’s vitally important, especially on surfaces that could snag a skid.

Which brings me back to my original point: why was he taking off from wet grass?

Fortunately, the pilot was not injured, although the helicopter was substantially damaged. I think this accident makes a good example for teaching about dynamic rollover. With luck, instructors and students will learn from the mistakes here and avoid them in their own training experiences.

Of course, another possibility is the the student pilot simply was not ready to solo.

Cockpit Distractions

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There’s a reason for a “sterile cockpit.”

The other day, I wrote a blog post about the four recent helicopter crashes that occurred during cherry drying operations here in Washington State. My point was to explore the possibility that pilots and operators were not taking this potentially dangerous work seriously. You can read that post here.

In giving this some more thought, I think that post neglected another indicator of not taking this work seriously: the concept of flying in a distraction-free environment — a so-called “sterile cockpit.”

Sterile Cockpit Defined

From Wikipedia:

The Sterile Cockpit Rule is an FAA regulation requiring pilots to refrain from non-essential activities during critical phases of flight, normally below 10,000 feet. The FAA imposed the rule in 1981 after reviewing a series of accidents that were caused by flight crews who were distracted from their flying duties by engaging in non-essential conversations and activities during critical parts of the flight.

Obviously, most — if not all — of a helicopter’s operations are below 10,000 feet. And helicopters performing cherry drying services aren’t subject to the same rules as airliners. So my point isn’t that helicopter operators are required to follow this rule. My point is that this rule exists for a reason.

When I went through the process of getting my Part 135 certificate, the topic of maintaining a sterile cockpit was brought up. My FAA POI was concerned about distractions during critical phases of flight. For my Part 135 operations, which consist primarily of tour and air-taxi services, that meant times when I’m in tower-controlled airspace, when I’m landing, or when I’m taking off. It also meant phases of flight operated at or below 300 feet AGL. The point being that when I’m communicating with a tower or close to the ground, I need to minimize distractions.

Distractions come in many forms. My POI’s main concern for me was chatty passengers. While I can normally perform landings at easy landing zones (LZs) without any problems — even while conducting a conversation with someone — when you add the need to listen to and look for other traffic, communicate with a tower, or deal with unusual conditions such as crosswinds or difficult landing zones, things are tougher.

For example, just the other day a very chatty passenger decided to start a new conversation just as I was on final approach to an off-airport, confined area LZ with a crosswind of 29 mph gusting to 36 mph. (We were about 1/2 mile from the airport, so that reading comes from an AWOS and is accurate.) When I didn’t answer her second question, she got the message and shut up. I have a switch I can flick to turn off cockpit chatter among passengers, but since I don’t usually need to use it, I didn’t flick it for that flight. Although the landing was fine, I’m thinking of a better briefing for passengers in the future.

Maintaining a sterile cockpit means eliminating all non-essential communication. It means reducing or eliminating distractions during critical portions of the flight.

Sterile Cockpits in Agricultural Work

Cherry Drying Near Wires
This is a photo I won’t show my mother. The helicopter’s airframe is probably about 20-25 feet from the wires in this shot by Patrick Schroeder. That’s as close as I’m willing to get.

Agricultural flying such as spraying, frost control, and cherry drying can be pretty intense. All of them require precision flying. Spraying is low level, at a relatively quick speed. Frost control is very low level, pretty slow, and usually done at night. Cherry drying is very low level and very slow, sometimes during or after weather that can obscure cockpit views. Obstructions are usually a concern for all agricultural flying work. These are conditions and flight profiles that could definitely benefit from a sterile cockpit.

I don’t think it’s a coincidence that most aircraft set up for spraying — whether they are helicopters or airplanes — are either labeled “Experimental” or have just one seat. These are not aircraft set up for passenger flight.

Imagine this scenario: A helicopter pilot is sent out to do some cherry drying. He’s been hanging around all day with a buddy who might even be another pilot. He invites him to come along. They head out over the orchard and the pilot gets to work. While he’s flying, he and his buddy are talking. Maybe one of them tells a joke and they laugh. Or maybe the buddy is texting with someone they both know and is relaying the conversation to the pilot. Or, worse yet, maybe the companion shows the pilot a photo from last night’s trip to the local sports bar on his smart phone. The pilot is not giving his full attention to the task at hand. He’s being distracted by his companion.

The Orchard Block from Hell
Who plants cherry trees under wires? Too many growers.

This isn’t so far-fetched — especially in a situation where the pilot and passenger aren’t taking the work seriously. Sure, the pilot is just hovering and the pilot has been doing that since he learned to fly. It’s not very difficult for an experienced pilot to do. But add obstructions and wind gusts during slow flight and it isn’t quite as easy. It requires more concentration — less distractions.

A sterile cockpit.

A Coincidence?

There were two people on board when three of the four cherry drying crashes occurred in this area over the past twelve months. I pointed this out in my recent blog post, but didn’t really think about the second person as a cause of distraction.

Could that have been a contributing factor? That the pilot was not focused on the work and allowed himself to get into a dangerous situation? That he didn’t react promptly because of distraction?

It’s certainly something to think about.