Trust but verify

November 1, 2003

Bruce Landsberg is the executive director of the AOPA Air Safety Foundation.

Former President Reagan's admonishment in dealing with foreign adversaries — trust but verify — certainly applies to pilots and controllers. The system of checks and balances works well most of the time, with pilots and controllers coming to depend on each other to keep the dance going safely. But all parties have to be actively engaged in holding up their end of the bargain. Letting down your guard, even momentarily, can have dreadful consequences.

Runway safety has been at the top of both the FAA's and the NTSB's lists for nearly a decade, and while we haven't had a major ground accident involving air carriers in this country for some time, the accident cited below is a reminder that it isn't just the big guys who tangle. Nearly all runway accidents occur at night or in periods of reduced visibility, which is logical. If you can see the other aircraft, the chances of collision go down dramatically unless the timing is really bad. This narrative and the accident chain are complex, but the lesson is simple. Most important, it applies to all pilots: low-time VFR students, CFIs, and high-time airline transport pilots (ATPs). They all figure prominently in this unfortunate scenario.

One spring day in 2000, about 10:35 a.m. Eastern Standard Time, a Cessna 172K, N79960, and a Cessna 152, N89827, collided during takeoff on Runway 14 at the Sarasota/Bradenton International Airport in Sarasota, Florida. Conditions were daylight VFR, the perfect case for see and avoid — which didn't work because of multiple human factors failures.

At 10:24:46, the Cessna 152 with a student pilot and CFI on board called the ground control/clearance delivery controller from the midfield ramp on the south side of the airport requesting a VFR departure. At 10:25:24, ground instructed the 152 to taxi to Runway 14. As the controller issued the taxi instructions, he was relieved by the supervisory ground controller ("ground"), who prepared a flight progress strip indicating that the airplane was instructed to taxi to the end of Runway 14 and passed it to the local controller ("local"). The initial ground controller then provided a briefing to his relief and left the tower cab.

At 10:25:46, the pilot of N52553, a Cessna 172, called for an IFR clearance. At 10:25:56, the pilot of N5287V, a Cessna 172RG Cutlass, transmitted the following message: "Sarasota clearance, Seneca, er, Cutlass Five-Two-Eight-Seven-Victor at Jones Aero [Jones is located on the north side of the airport] with Mike...negative radar to Clearwater Air Park." At 10:26:11, ground issued a Class C clearance and transponder code to N5287V. The pilot then indicated that he was ready to taxi and was instructed to taxi to Runway 14 at Foxtrot intersection. The controller prepared a flight progress strip on the 172RG indicating "14/F" and "PASE" (but mistakenly indicated the Cessna 172RG as a Piper Seneca). The Cutlass pilot stated that he "missed the last part," and the controller repeated, "Expect the Runway 14, Foxtrot intersection." At 10:26:46, the Cutlass pilot acknowledged, but the last part of his transmission was covered by the initial call of Cessna 172 N79960. N79960 was told to stand by and the controller issued an IFR clearance to Cessna 172 N52553. The environment was somewhat busy, slightly confused but reasonably normal.

At 10:28:03, the Cessna 172 pilot of N79960 stated, "At Jones and ready to taxi." Ground issued a Class C clearance and transponder code, which the pilot acknowledged, and the controller instructed him to taxi to Runway 14, which the pilot acknowledged. The controller prepared a flight strip on N79960 indicating "14." N79960 proceeded via Taxiway F and held short of Runway 14 at the intersection. At 10:28:52, the pilot of Cessna 172 N52553 stated that he was "ready to taxi." Ground confirmed N52553's location at the south ramp and issued taxi instructions to Runway 14, which the pilot acknowledged. At 10:29:41, N9801Y, a Mooney that had just landed, requested a taxi back to Runway 14. The controller missed the call, asked the pilot to repeat his request, and then told the Mooney to stand by. At 10:30:33, the pilot of N215JA, another Cessna 152 at Jones Aero, called for taxi instructions and was instructed to taxi to Runway 14 at Foxtrot. At Taxiway A (the northwest end of Runway 14), N89827, N52553, and N9801Y were waiting in sequence; at Taxiway F, N5287V, N79960, and N215JA were waiting in sequence.

If you're still with me, in the space of a little more than six minutes there were multiple contacts with multiple aircraft in multiple locations. This is what ATC does and it works very well, but some minor errors had crept into the sequence. The seemingly inconsequential slip-ups were about to become critical.

At 10:30:42, the Cessna 152 student pilot of N89827 made his first contact with local: "Ready for takeoff," and was instructed to hold short. At 10:31:08, the controller asked, "Who's at the approach end of Runway 14, ready to depart?" The pilot of N89827 replied, "Eight-Two-Seven," and the controller stated, "I show you at Foxtrot." At 10:31:15, the pilot of N5287V transmitted, "No, sir, that's Eight-Seven-Victor at Foxtrot"; local acknowledged the transmission. At 10:31:29, local asked the pilot of N5287V if he was ready to depart; the pilot responded, "Affirmative." The tower stated, "I show you as a Seneca...you're not a Seneca, are you?" The pilot replied, "No...I'm used to flying a Seneca." Local instructed N5287V to hold short.

At 10:32:46, the pilot of N79960 made his first contact with local: "This is...Nine-Six-Zero, we're number two ready for takeoff." Local advised N79960 that he was "number three for departure, hold short." At 10:33:57, local instructed N89827, "Runway 14, taxi into position and hold, traffic will depart down field also." At 10:34:06, local instructed N5287V, "Runway 14 at Fox, taxi into position and hold." The pilot acknowledged and at 10:34:22 was cleared for takeoff from the Taxiway F intersection.

After N5287V became airborne, at 10:34:43, local cleared Cessna 152 N89827 for takeoff from the end of Runway 14, which the pilot acknowledged. At 10:34:51, eight seconds later, local instructed Cessna 172 N79960 to "taxi into position and hold," which the pilot acknowledged. Witnesses reported that the 152 had reached takeoff speed when the 172 entered the runway from the left side. The 152 lifted off early, turned right in an attempt to avoid a collision, then stalled and crashed into the Skyhawk. Both airplanes burst into flames — there were no survivors.

The Cessna 172 was piloted by an ATP with 13,000 hours and multiple instructor ratings. He had flown 142 hours in the 90 days preceding the accident. The other pilot in the Skyhawk was a Canadian private pilot with nearly 2,000 hours total time. A commercial-rated flight instructor with 340 hours total time including 15 hours of dual given, and a student pilot crewed the Cessna 152.

Clearly, the local controller was confused as to which Skyhawk was which. Two Cessna 172s, two Cessna 152s, a Cessna 172 retractable that momentarily thought it was a Seneca, and a Mooney were all waiting for departure just before the accident sequence began. In a post-accident interview with the NTSB, the local controller stated that in addition to this group, there were two airplanes airborne; one in the traffic pattern and another executing a practice approach.

The local controller allowed that some confusion initially existed concerning the locations of N89827 and N5287V. After he observed N5287V become airborne, he cleared N89827 for takeoff and then mistakenly instructed N79960 to taxi into position and hold. The controller recalled the pilot transmitting "number two," and the flight progress strip indicated "14." He saw two Cessnas on Taxiway F "facing into the wind, in [the] runup position." This reinforced his belief that N79960 was behind N89827 at Taxiway A at the end of the runway, not at the intersection of Foxtrot.

After issuing "position and hold" to N79960, the controller scanned the final approach area and "may have looked at the BRITE [local radar] display." He also noticed that a Cessna holding short at Taxiway A was not moving; however, he attached no significance to that "because sometimes they're slow to go into position, they take a while." When he again looked at the runway the collision occurred.

The tower's system of tracking aircraft didn't work optimally this day. The flight strips were not properly marked, making local's job more difficult. Several pilots were less than clear about their locations, which didn't help. Many pilots assume that the tower can see and identify them. That's not necessarily true, especially when there are multiple aircraft of the same model calling for instructions from the same location simultaneously. The tower could be well away from the action.

The tower didn't get it right but the pilots involved, especially Cessna 172 N79960, were in the best place to stop the accident sequence once it started. The Aeronautical Information Manual recommends that "pilots state their position when calling the tower for takeoff from a runway intersection." The ATP failed to advise the tower that "Cessna 79960 is ready for takeoff on Runway 14, at Foxtrot, number two" or words to that effect. That would have broken the chain right there, but there was still one more chance. It should be every pilot's mantra to trust but verify by visually clearing the runway in both directions before entering, even when the tower says it's OK to enter or cross.


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North Las Vegas runway incursion

As this issue was going to press there was a collision at a North Las Vegas Airport runway intersection involving a Piper Arrow and Piper Mirage The investigation is in the preliminary stage at this writing and thus information is subject to change. It should be noted that North Las Vegas is one of the worst airports for runway incursions. It appears that the tower cleared the Arrow to land and shortly after that cleared the Mirage for takeoff on a crossing runway. The Mirage was on the ground control frequency and the pilot did not hear the tower clear the Arrow to land. The collision occurred exactly at the intersection of the two runways with the Mirage on the ground at the time of impact. It is too early to tell exactly what the causal factors were. However, as in the Sarasota accident, this does reinforce the importance of verifying clearances, clearing runways and being highly aware of other aircraft in the vicinity. There may be very little time to make a life-saving decision. — BL