Wednesday, July 29, 2009

Bermuda Triangle

Pilots often think the real work surrounding flying begins once they are airborne, probably because taxiing for takeoff or after landing usually doesn't seem very demanding, interesting, or dangerous. Some of my more harrowing moments in airplanes have occurred during ground operations and the years have taught me that planning, organization, and situational awareness on the ground during single pilot operations can be just as critical as when you're airborne.

The FAA, recognizing the importance of safe ground operations, has published AC 91-73A: Part 91 and Part 135 Single-Pilot Procedures During Taxi Operations, which divides single-pilot ground operations into planning, situational awareness, written taxi instructions, radio communication, and finally taxiing itself. It's a pretty good read, especially for seasoned pilots who may have become a little complacent, and it got me thinking of some of the more memorable experiences I've had while I was just taxiing.


The AC suggests that pilots use SOPs (standard operating procedures) which should be introduced during initial training, applied during each flight, and evaluated during recurrent training. The problem is that GA pilots whose initial training was accomplished under part 61 often have little exposure to SOPs, other than their instructor's biases and what they see other pilots do. My wife says that dogs mostly learn bad habits from other dogs and the same could be said for pilots, so here are some recommended practices for single pilot ground operations.
  • Get a briefing and check for NOTAMs
  • Write down taxi instructions
  • Have the airport diagram out and refer to it
  • Avoid distractions during taxi, like programming the GPS
  • If reading a checklist, hold it up so your peripheral vision is outside
  • If confused about your taxi clearance, get clarification
  • Don't be bashful about asking for progressive taxi instructions
  • Expect the unexpected at non-towered airports, even on the ground
Have a Plan

Before calling for taxi, especially at an unfamiliar airport, it's good to review the airport diagram and mark any NOTAMs for taxiway or runway closures or other changes. Listen to the surface weather (ATIS, ASOS, or AWOS) to determine which runways are in use and look at the airport diagram and estimate the best route to the departure runway. That way when you get your taxi clearance, you'll more likely actually understand it. Jeppesen, for their part, marks hot spots on their airport diagrams and even includes some description of why the areas require special attention.

At larger towered airports, the airport diagram will list all the various clearance delivery, ground, and tower frequencies that you'll need to use. If I had a dollar for every time a pilot asked me what a particular frequency was, I might be sitting on a warm beach, sipping a cool beverage.

Becoming a Literate Pilot

As pilots gain experience I've noticed that many tend to skip the step of writing down the taxi instructions they receive, mistakenly thinking that this is what experienced pilots do. Writing down taxi clearances is easy, especially if you always do it as part of your own personal SOPs.

One morning I called for taxi and got a much more complicated clearance than I had expected. I was used to hearing "taxi runway 28 left via Alpha" but instead was given "taxi 28 left via Delta, Zulu, and Zulu One, hold short 28 right."

A recent change to ATC procedures requires ground controllers to specify the taxiways leading to your departure runway. I heard a pilot recently ask a controller if they had to read back the route, as if it were really that much trouble to do so. I often marvel at how some pilots expend considerable energy in seeing how much they can get away without doing rather than just doing what they know they should.

Be careful that you don't mistakenly hear, write, and read-back the taxi clearance you expect to get. If you read back the incorrect clearance, the controller may not catch your error, hearing what they expected you to say (sometimes called a hear-back error).

Mental Picture

Referring to your airport diagram during taxi can help keep you from making a wrong turn, but it's not foolproof. And don't rely on the ground controller to keep you out of trouble, as witnessed by this takeoff accident where a combination of factors led to the crew taking off on the wrong runway with disastrous results.

I've learned to be especially alert when I hear one controller working both the tower and ground frequencies, which is routinely done at my home airport later in the evening. While I understand that staffing considerations may drive these practices, it carries additional risks for pilots operating on the ground.

One night I called for taxi from the fuel island to parking. I received and read back my clearance. As I began taxiing, I noticed a Lear rolling out on the runway adjacent to my taxiway, both of us approaching a particularly confusing intersection of taxiways locally known as "The Bermuda Triangle." As the Lear taxied off the runway, I heard only the tower's side of the conversation as he was working both tower and ground while the Lear crew was still on the tower frequency. Keep in mind that the Lear and I were the only two aircraft on the field.

I heard the tower say "Lear 123, taxi to parking." After a pause, I heard the tower say "You can take either route" and I knew it wasn't good. Sure enough, the Lear crew chose the route that brought them straight at me - at a high rate of speed I might add. The controller had not said a word to either of us about the other. Sensing a collision was imminent, I turned on my strobes, added power, and sped past just as the Lear's wingtip missed the end of my plane by what I estimate was less than 10 feet. There wasn't any time to say anything on frequency and since the Lear was still on tower and I was on ground, it wouldn't have helped anyway. I have no idea if the Lear crew even saw me.

Eyes Peeled

Several years ago another pilot and I narrowly avoided being hit by another aircraft while doing our engine run-up. The preflight and taxi had been uneventful, but during the engine runup we noticed an anomaly in one of the cylinder head temperature indications. This led us to stay in the runup area longer than usual as we tried to figure out what was causing the high reading. The longer the engine ran, the more the cylinder head temperatures normalized. To fly or not to fly?

We had just resolved to stay in the pattern and watch the engine closely when I caught a glimpse of the aircraft that was headed straight for us. It was a home-built, tailwheel aircraft and I found myself asking aloud "Why is he taxiing so damn fast?" followed by "Jesus, he's not going to stop!" I was certain he would hit us, but at the last moment he jammed on his brakes. This raised the tail of his plane into the air, buried his prop in the pavement, and his craft slid to a stop on it's nose just short of our propeller. We told the ground controller we'd had a near collision in the runup area, that we'd be exiting our aircraft, and that we'd remain clear of the taxiway. The other pilot apologized and confessed he was headed into the sun and hadn't see us.

Speak Up

If you see a conflict unfolding that the ground controller is not aware of, it's critical to say something on the frequency. I frequently see pilots seem to just freeze in these circumstances and wonder why this is so. Perhaps it's because pilots feel intimidated by controllers or mistakenly believe they must always follow their instructions, even if those instructions are going to put their aircraft in harm's way.

Taxiing out for takeoff a few weeks ago, I heard a Gulfstream call for taxi, too. We got our clearance, joined the taxiway and headed to the run-up area. The Gulfstream got their clearance to the South Field and ended up behind us, taxiing in the same direction. That's when we heard a 727 taxiing from the South Field switch to the North Ground frequency. The 727 was ultimately going to be headed in the opposite direction. I knew there was time for us to get into the run-up area and get out of the way, but the ground controller now had a conflict between the Gulfstream and the 727. The controller ended up having the Gulfstream do a 180 degree turn on the taxiway, then taxi onto an adjacent runway so the 727 could pass. And I was glad that we had gotten our little plane well downwind of all the jet blast!

On another occasion, I was taxiing with a student to a local FBO's ramp as a Global Express on the same ramp called for taxi. Ground told him to wait and pass behind us, but I didn't like how that was going to unfold: We'd end up parked right where his jet blast was going to be as he powered up to taxi out. So I suggested to ground that we hold our position on the taxiway a hundred or so yards away and let the bigger guy taxi out, which worked out to be a much better solution for everyone.

Approach Briefing

When you brief your approach to an airport, don't forget to think about where you're going to head once you're clear of the runway. This is a good time to get your airport diagram ready and review what your desired taxi route will be. Don't forget to consider any NOTAMs included on the ATIS you recorded. You did listen to the entire ATIS, right?

Post-Flight & Good Night

You can make your ground operations safer by developing your own SOPs, writing down your taxi clearances, having the appropriate charts available, and thinking ahead. And if something doesn't look right, speak up. You just might prevent some bent metal, cracked composite, or worse.


Marquinius said...


I've been following your blog for a while now, but this is really a fantastic post. I'm just a humble private pilot trying to take in as much as possible, but the issue of taxiing on bigger airfields is indeed worth just as much attention as the flying. It amazes me that some people just fly into some port and from there stumble along. I'd be scared sh*tless doing that.

Oh well, some people even dare to fly abroad with only 12 hours per year experience.

Steve said...

Just wanted to say thanks for the great post. Lots of great personal experiences to go along with very valuable advice for any pilot!