Taxiway Incursion

It was not a good day for Air Traffic Control and aircraft movement on the ground.

My MD-88 flight from Atlanta rocketed down final approach at the Class C primary airport in Florida this hot Monday morning. From seat 19A I spied a Seneca in the run-up area at the end of the eastbound runway. (A lot of flight training originates from this airport.) The twin Piper sat cocked into the wind, the forward cabin door open as the instructor tried despondently to capture some of the last of the prop blast before sentencing himself and his student to the broiling cabin.

A bump and a squeal and the big jet plunked down, its crew zealously pumping the power levers into reverse in that familiar, seemingly over-aggressive stop-short used by the big jets regardless of the distance of runway remaining. As we decelerated I noticed a blue-striped Cessna 172. Also eastbound but on the parallel taxiway it meandered toward the training ramp. We passed the Skyhawk as the jet slowed to an airliner’s trot.

The MD didn’t stop before swinging left toward a turnoff that connected the runway with the parallel taxiway. The stretch of pavement between runway and taxiway was barely the length of the long-body airliner. The airliner’s crew made the 90-degree turn with the cockpit swinging toward the west — and right at the taxiing Cessna. You could feel the panic in the crew as they leaned on the brakes, which groaned under the strain. It was abrupt enough of a stop that the nosewheel compressed and the MD rocked fore-and-aft two full cycles once we were stopped. The Cessna’s complement of student and CFI proceeded without pause, either oblivious to the mass of metal mere feet away or confident that the airline crew could never roll into its path. Luckily, the MD-88 pilots saw the Skyhawk … and the MD’s brakes were good enough to stop the rapid turn-off.

For several years “runway incursion” avoidance (staying off active runways until properly cleared) has been a “hot topic” among FAA inspectors, and is even now required to be discussed in Flight Reviews and Instructor Refresher Clinics (FIRCs). The Aircraft Owners and Pilots Association’s Air Safety Foundation has an excellent on-line review of taxiing instructions and techniques for dodging the runway incursion bullet at As a provider of Flight Reviews and a recent FIRC graduate I’ve seen and delivered runway incursion avoidance training. But after just witnessing this near-collision as we taxied off the active runway — a collision that would likely have crushed the Cessna’s occupants to death — I had to ask: who was “right? I vowed to review the guidance pilots have about re-entering the taxiway environment after landing, and avoiding collision on taxiways and ramp areas.

Turn left at the next taxiway, contact ground on 121.9.

Tower direction to exit the runway does not clear you onto the taxiway to which it connects. Here’s what the Aeronautical Information Manual (AIM) has to say about exiting the runway after landing (AIM 4-3-20) (author’s emphasis in bold type):

The following procedures should be followed after landing and reaching taxi speed.

    1. Exit the runway without delay at the first available taxiway or onto a taxiway as directed by ATC. Pilots should not exit the landing runway onto another runway unless authorized by ATC. At airports with an operating control tower, pilots should not stop or reverse course on the runway without first obtaining ATC approval.
    2. Taxi clear of the runway unless otherwise directed by ATC. In the absence of ATC instructions the pilot is expected to taxi clear of the landing runway by clearing the hold position marking associated with the landing runway even if that requires the aircraft to protrude into or cross another taxiway, or ramp area. This does not authorize the aircraft to cross a subsequent taxiway/runway/ramp after clearing the landing runway.

Translation: You’re not “clear” of the runway until the entire airplane is completely past the “hold short” line separating the taxiway from the runway environment. After landing, ATC (and other, taxiing pilots) expect you to get completely clear of the runway … but no further until cleared by Ground Control. AIM 4-3-20 continues…

  1. Stop the aircraft after clearing the runway if instructions have not been received by ATC.
  2. Immediately change to ground control frequency when advised by the tower and obtain a taxi clearance.

My personal experience is that tower often will tell me to clear the runway as soon as practical, and to contact ground control. I’ll make the turnoff and switch frequencies, only to have to wait through several other pilots’ transmissions before I can request a taxi clearance. I’m sitting all alone out at the end of the short (general aviation) runway with no one else in sight. Can I begin taxiing? No. I have to sit right where I am — barely clear of the runway — until ATC authorizes me to go somewhere else. On the ground and newly switched to ground control frequency, it’s impossible to see the “big picture” right away and know where you fit into the ground-traffic flow.

So who was “right” — the Cessna instructor and student, or the crew of the MD-88? It depends. If the turnoff was long enough for the MD-88 to completely clear the runway without penetrating the parallel taxiway, then it was the jet crew’s responsibility to stop before hitting the Skyhawk. If the turnoff was too short for the tail of the MD to clear before the nose was over the taxiway, then the jet crew was “right” in turning in ahead of the Cessna.

The Point: Regardless of who is “right,” anticipate what the other guy might do, and stop or adjust your path if needed. Just as when in the air, pilots have a responsibility to SEE AND AVOID on the ground.

Once on the taxiway you’re pretty much on your own as far as separation. Often ground will ask you to “give way to the Cessna” or “Follow the Learjet” to your runway or ramp, but remember that the primary function of Ground Control is NOT to separate traffic on the taxiways, it is to PREVENT AIRPLANES FROM ENTERING ACTIVE RUNWAYS until cleared. ATC will monitor taxiing airplanes to the extent possible, but keeping them separated is not what Ground Control is about.

Keep your taxi diagram out and refer to it as needed for taxi directions. If you have questions, ask ATC. If you’re confused or lost, STOP where you are (as long as you’re clear of a runway) and work it out. Not familiar with the airport? Ask Ground for a “progressive taxi, and they’ll give you precise directions, including when and where to turn as you “progress.” Remember you’re still responsible to avoid collisions.

Once on ramps, taxiing between hangars, or in tie-down areas, you’re usually beyond the sight and authority of Ground Control. In fact, ramps and tarmacs are called “non-movement areas” by ATC, not because things don’t move there (of course they do), but because ATC exercises no control over them. You can taxi around the ramp at the busiest airport all day long without talking to Ground Control, so long as you stay in the non-movement area … but you’ll probably annoy some people and foul your plugs.

Since there’s absolutely no one looking out for you in non-movement areas, and because of the natural concentration of airplanes, ground vehicles and pedestrians, use extremely caution when taxiing on the ramp. This is no time to be programming your GPS, dialing frequencies, folding your charts, referring to checklists or calling the FBO with your fuel order — STOP if you need to do any of these chores. Keep your speed down (remember that FAA “walking pace” taxi we all learned as a student pilot? Here’s where you use it). And keep your head up when taxiing, especially in non-movement areas.

When visibility’s poor controllers often cannot see all taxiways and runways from the tower. They depend even more on pilots for position awareness and keeping clear of the runways. Proceed with extreme caution, using your runway diagram and eliminating “cockpit chore” distractions, when taxiing in periods of poor visibility.

Note: Some large airports are installing Surface Movement Guidance and Control Systems (SMGCA, commonly called “SMIGS“). Additional surface signs and lighting enhance aircraft movement when “see and avoid” becomes impossible.

In the Crystal Ball: In our future also is widespread use of ground radar at air carrier airports. Remember how we’re supposed to turn off our transponders on the ground to avoid overwhelming ATC radar? Many new airplanes even automatically cut off the transponder when there’s weight on the wheels. The paradigm is changing, though — expect in the future to be told to keep your transponder ON while on the ground — to “work the system” of ground control.

THE BOTTOM LINE: In almost all cases, ATC direction to taxi does not provide separation from objects or other airplanes. Certainly at non-towered airports aircraft movement on the ground is entirely the responsibility of the pilot-in-command. Even when talking to Ground Control at a tower-controlled airport, the AIM reminds us that “it is the responsibility of the pilot to avoid collision with other aircraft.” Running into things can hurt. Do nothing fast on the ground, and keep your eyes and ears open for other airplanes wanting to use the same patch of pavement as you — to avoid taxiway incursions.

Editor’s Note: For more, see also:
Jeff Pardo’s, “Clear of the Active” and Paul Craig’s, “Two Planes, Two Runways, One Intersection