Runaway Incursions?

Though some would have you think runway incursions are on the rise, its not that simple


Among pilots, the perception of whats safe is forever clouded by the tree-falling-in-the-woods syndrome. If no ones there to hear it, does it still make a thud?

The aviation safety corollary has to be the accident stats numbers game. When a trend seems to surface, was it there all along or are we just noticing it because we happened to be looking?

Such may very well be the case with the FAAs current safety problem child – runway incursions. According to data collected by the agency, runway incursions are at an all-time high and rising.

Worse, most of them are committed by general aviation pilots, giving the impression that the average Bonanza or Piper owner is bumbling around the taxiways like a blind mole looking for his burrow until – surprise, hes a hood ornament on a DC-10.

Unfortunately, a recent accident in Florida may raise legitimate concern about this issue to a shrill crescendo, obscuring an important concept many pilots fail to grasp: Control towers are staffed by humans who make mistakes and relying on them to the exclusion of looking out the window may be worse than having no tower at all.

The Numbers
Such is the worry about runway incursions that the FAA has devoted an entire task force to addressing the problem. The Runway Safety Program office even has its own website at At press time in mid-March, the agency announced plans for a major initiative to train controllers in incursion avoidance.

Overall, the RSPs goal is laudable: to introduce methods to reduce runway incursions. In the service of this goal, the RSPs site has posted 10 years worth of runway incursion stats.

These are divided into three broad categories: Controller-caused incursions – known in the trade as operational errors, pilot errors or deviations, and airport vehicle or pedestrian incidents. (Yes, people do stumble out onto active runways and taxiways, sans airplanes.)

From 1988 to 1998, the number of reported incursions more than doubled, from 187 to 325 in 1998. In the intervening years, incursion totals have been inconsistent: sometimes up, sometimes down. In relative terms, incursions caused by controllers (operational errors) have remained relatively constant, averaging about 90 a year since 1988.

Pilot deviations, on the other hand, have risen in a spikey curve from 68 in 1988 to 183 in 1998. If the data are accurate, thats a dismal record and, according to the FAA, GA pilots are the ones most frequently involved in runway incursions.

Whether the data are accurate may be open to question, however. In the not-too-distant past, ATC facilities were likely spotty in their incursion reporting standards, and facilities have been known to bury their own operational errors for the sake of expediency.

With the incursion issue on the front burner and facilities being told in firm tones to quit fooling around and report incursions, thats exactly what theyre doing. Not that we doubt incursions are up, but were skeptical that theyre up as much as claimed.

If actual incursions were skyrocketing, we would expect by random chance to see more incursion accidents, and that hasnt been the case. Near-accidents – say an airplane crosses a runway with another aircraft rolling for takeoff or braking after landing – may not necessarily be the hazard they are portrayed to be, although the potential for disaster is ever-present.

When they do happen, however, incursion accidents tend to be spectacular and grimly memorable. The 1990 runway collision between two Northwest Airlines aircraft (a DC-9 and a 727) at Detroit comes to mind. So does the collision of a USAir 737 with a commuter on the runway at Los Angeles International in 1991.

More recently, two single-engine Cessnas collided on the runway at Sarasota-Bradenton, Florida, killing all four occupants of both airplanes. More grist for the runway incursion mill? Definitely – and probably contributory to the perception that runway incursions are out of control.

Is Anybody Looking?
Sarasota is a busy towered airport located on Floridas west coast. Like most Florida airports, it sees plenty of training activity with a mix of airline and fast GA airplanes. On March 9, the day of the accident, a gaggle of airplanes, mostly Cessnas, was taxiing for takeoff on runway 14, the 7,003-foot main runway. Two were approaching the runway from a flight school ramp on the west side of the airport, two from the northeast side.

Number one for takeoff was a Cessna 152, with a Cessna 172 or some other high wing airplane immediately behind it. Two more 172s were holding short downfield for an intersection takeoff at Foxtrot, an intersecting taxiway that joins the runway from the northeast side of the field.

The Cessna 152 was cleared into position and hold, and shortly after that one of the downfield 172s was also cleared into position from Foxtrot and promptly cleared for takeoff. At this point, the 152 was holding on the runway with a 172 behind it holding short and another 172 holding short at Foxtrot.

Looking out the tower cab, the local controller cleared the 152 for takeoff and instructed the Cessna 172 holding short at 14 to taxi into position and hold. At least thats what the tower controller apparently intended.

In fact, because of what appears to be confusion over which Cessna was which due to a flightstrip marking oversight, the controller told the downfield 172 to taxi onto runway 14 from its hold-short position, directly into the path of the rolling 152. His attention was distracted momentarily and he looked up to see the two colliding. Although the 152 pilot attempted a last second hurry-up rotation, the two aircraft exploded in flames, killing all four occupants.

Whos to blame here? Well let the NTSB sort through the fault-finding process but two things are obvious: ATC fouled up by directing the 172 into the path of the 152, possibly because a supervisor filling in for a ground controller on break wrongly assumed one of the Foxtrot Cessnas (the second) was taxiing from the west ramp, not the northeast ramp. He erroneously marked the flightstrip to indicate this.

Second, the pilots in both airplanes – one of which had a CFI, the other an ATP, plus a student and rated pilot – evidently accepted their ATC clearances at face value, possibly without so much as a confirming glance.

In broad daylight, the downfield Cessna 172 especially should have had an unobstructed view of the Cessna 152 rolling directly toward it down runway 14. Why the right-seat occupant, a CFI, didnt simply glance down the runway before entering will probably never be known.

In the interests of self-preservation, you wouldnt consider entering a runway at a non-towered field without checking for traffic. Should it be any different at a towered field? At the core of this question is a persistent misunderstanding about what towers at controlled fields really do.

No Separation
Misconception one: Towers provide airborne separation. At a Class D towered airport, this is simply false. All the tower is required to do is handle sequencing of arriving and departing aircraft and traffic advisories.

The accident record is rife with midair collisions in Class D airspace, when both airplanes were talking to the tower and both controllers and pilots knew – or thought they knew – where everybody was. But the fact is, pilots often dont know where they are. They misreport direction and distance, they claim to be over landmarks when they arent or they become temporarily confused, especially at unfamiliar airports or at night.

Controllers make mistakes, too. They report traffic east of the field when they mean west; they misjudge distances and misidentify aircraft whose N-numbers they cant read at a distance. Its not unheard of for ATC to actually bring airplanes together in a Class D pattern because of confusion about position and distance.

Some Class D towers have BRITE radar repeaters and these help nail down position and distance. (If a tower controller asks you to ident, hes probably looking at you on a BRITE.) Nonetheless, the key survival skill in towered airspace is to operate as though you were in plain-vanilla Class E airspace, where there is no tower. In other words, tower traffic advisories based on pilot position reports are as likely to be wrong as right.

In Class B and Class C airspace, separation is required and provided, in part because radar is available to the surface – or nearly so. Nonetheless, in visual conditions, looking out the windows is still a must. (Sarasota is Class C airspace, by the way.)

On the Runway
At Class D airports, all towers do, other than issue advisories and sequencing, is to guarantee runway separation. This leads to a second misconception: Youre always guaranteed a clear runway for takeoff and landing.

The truth is, more than one airplane can legally and safely occupy the runway at the same time. The full litany of runway separation requirements is outlined in the controllers manual and, for operational purposes, pilots neednt know the details.

Runway separation is determined by aircraft category. Category Is are small airplanes or single-engine props, Cat IIs are larger props (12,500 pounds and up) and Cat IIIs are everything else.

The important separation criterion to remember is 3,000 feet, which is the minimum runway separation between two light aircraft using the same runway in visual conditions. That means if youre on final with a tight following sequence and see an airplane rolling out on the runway in front of you, the controller can legally (and safely) allow you to land if he determines that at least 3,000 feet of separation will be maintained when you touch down.

In practice, many tower controllers dont apply this separation, but issue a go-around if any airplane occupies the runway while another is about to land. Who knows if this means controllers dont trust pilots well enough to stop in time to avoid a collision or whether they just dont want to be bothered estimating the runway distance? Perhaps a little of both. (Runway distance is determined by reference to suitable landmarks. In other words, it requires judgment.)

As PIC, youre under no obligation to accept a clearance predicated on the controllers minimum runway separation judgment. If you dont like the idea of landing 3,000 feet behind another airplane, its your prerogative to go around. Say as much.

For takeoffs, the Cat I separation rule is that the preceding aircraft will have crossed the departure end of the runway or turned off the runway centerline before the following aircraft is cleared for takeoff.

No Guarantees
Were these separation standards followed at Sarasota? The intent may have been there but separation was obviously lost on the runway.

Following the rules to a fault is no guarantee that airplanes wont collide on the runway. What appears to have happened at Sarasota is a mix-up in aircraft ID. The controller confused which airplane was which and cleared the wrong one into position-and-hold. An erroneous flightstrip marking – /14 – may have misled the tower controller into believing the hold short airplane was at the end of runway 14 rather than at the intersection.

At major terminals – OHare, for example – ATC has evolved a procedure for backstopping some control errors. A dedicated control position called a monitor plugs in in parallel with controllers working critical positions. The idea is that the monitor will catch any potential metal-merging error in time to correct it. Nice idea but not so hot in practice. The monitor has to be fully engaged at every moment and practice has shown that they arent.

No monitors were in place at Sarasota, thus the backstop on any runway, takeoff or landing clearance has to be the pilots. Unreasonable? Hardly, especially in daylight visual conditions.

Youd look out the window at an uncontrolled field; theres no reason not to do the same at a towered airport. Second, position awareness is just as important on the ground as in the air if the runways are busy.

When youre being vectored for the approach in the clag, listening to the radio traffic gives you a mental picture of where everybody else is and what your sequence will be. The same can be said of tower and ground freqs, where you can both hear and see the traffic picture.

Before accepting a position-and-hold, replay your mental communications tape.

Did you hear someone cleared to land? Did you hear a downfield taxi clearance? It takes mere seconds to simply look in the direction of a potential threat, even if the radio is silent, as it very well might be when tower and ground are working split frequencies.

If the pilots in that downfield Cessna had done just that, you wouldnt be reading this.

Also With This Article
Click here to view “When Controllers Make Dangerous Commands.”
Click here to view “Runway Accident.”

-by Paul Bertorelli

Paul Bertorelli, a CFII and ATP, is editor of The Aviation Consumer.


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