Ambiguous ATC

A controller’s omission of sequencing information in a landing clearance leads to a stall/spin accident.


The ship has long since sailed, but labeling air traffic controllers as “controllers” has been something of a disservice to pilots everywhere. That simple convention has conferred on those responsible for separating traffic in the air and on the ground an authority over the outcome of a flight they really don’t have. Perhaps “coordinator” or “counselor” would have been better job titles.


The problem is relatively simple: Many pilots want to follow a controller’s instructions regardless of how safe or reasonable they may be simply because they’re issued by a “controller.” In most cases, the instruction is benign, appropriate and safe. In extreme cases, however, an instruction can lead pilots to do something unsafe or beyond the aircraft’s capabilities.

Yes, in such instances the ultimate fault lies with the pilot, who should know better than to allow ATC to place him and his aircraft in a risky situation. In those instances, the pilot should refuse the instruction, offer an explanation and ask for something different. But controllers—just like pilots—are human and they make mistakes. Here’s an example of what can happen when both sides make them.

On February 29, 2012, at about 1701 Eastern time, a Cirrus SR22 was substantially damaged when it collided with terrain following an uncontrolled descent while maneuvering for landing at the Melbourne International Airport (KMLB) in Melbourne, Fla. The private pilot and two passengers were fatally injured. Visual conditions prevailed. There were several aircraft operating at the airport that afternoon and simultaneous operations to parallel Runways 9L/R were being conducted at the towered facility.

The accident pilot’s initial call-up occurred at about 1658, when he reported five miles south of the airport, requesting a full-stop landing. The 500-hour pilot was instructed to report established on a right downwind for Runway 9R. Shortly thereafter, the controller advised the pilot he could either land on Runway 9R, or extend his downwind approximately six miles to follow traffic for Runway 9L. The accident pilot responded requested 9R and a long landing to reduce taxi time to the FBO. At 1700:16, ATC cleared the accident airplane to land on 9R.

Shortly before this exchange, another Cirrus, an SR20, was cleared for a touch-and-go landing, also on 9R. Aboard the SR20 were a flight instructor and pilot. At the time, the SR20 was approximately five miles out on a straight-in approach to 9R.

At 1700:47, ATC asked the accident pilot to confirm he had the SR20 in sight, noting it was on a one-mile final approach for 9R. The accident pilot replied he was on a “real short base” for 9R. At 1700:57, the controller responded, “No sir, I needed you to extend to follow the Cirrus out there on a mile final. Cut it in tight now, cut it in tight for 9R.”

An airliner’s first officer awaiting takeoff clearance from Runway 9R later stated he saw the accident airplane at “about 200-300 feet agl…in a right turn of 30-40 degrees of bank descending for the runway.” The airplane then made an “abrupt” left turn, while simultaneously leveling or “attempting to climb,” and “clearly initiated an accelerated stall” at about 150-200 feet agl. The airplane continued to roll left until inverted, and then descended nose-down to ground contact.

As the accident pilot was advised of the SR20’s position on short final, it was about 300 feet below and a mile to the west of the traffic. By the time ATC told the accident pilot to “cut it in tight,” the two airplanes had closed to within a half mile but were still separated by 300 feet of altitude.

When he heard the accident pilot report his position on right base for 9R, the SR20’s flight instructor assumed control, increased power and began a “shallow climb/turn” to the left towards the grass infield between the parallel runways.

The SR20’s flight instructor further stated, “[The controller] was yelling at him on the radio. I don’t remember the exact words but the more tower yelled, the more the aircraft yanked and banked. I then witnessed an accelerated stall, 90-degree bank angle with a one-to-two-turn spin that ended up nose-first into the ground.”

Data recovered from the accident airplane’s avionics depicted it descending at about 500 fpm and slowing to about 100 KIAS in the last minute of flight. At 17:00:56, engine rpm increased from about 1500 to 2000, and the airplane rolled left until it was inverted. At 17:00:59, the airplane began to pitch down, reaching an approximate 65-degree nose-down attitude and about a 2000 fpm descent before recording stopped at 17:01:04.

The airliner’s first officer and other witnesses observed the accident airplane’s airframe parachute deploy prior to ground contact. Based on occupant weights and the accident airplane’s fuel load, its estimated gross weight at the time of the accident was 3379 pounds, 21 pounds under its maximum. Weather observed at KMLB a few minutes before the accident included wind from 130 degrees at 13 knots, gusting to 18 knots, clear skies and 10 miles of visibility.

Probable Cause
The NTSB determined the probable cause(s) of this accident to include: “The pilot’s abrupt maneuver in response to a perceived traffic conflict, which resulted in an accelerated stall and a loss of airplane control at low altitude. Contributing to the accident was the air traffic controller’s incomplete instructions, which resulted in improper sequencing of traffic landing on the same runway.”

During its investigation, the NTSB interviewed the controller, who said he expected the accident airplane “to report when it entered the downwind leg of the traffic pattern as instructed, and subsequently complete a ‘normal’ traffic pattern and land behind the Cirrus SR20 on final approach. However, examination of communications recordings revealed that the controller cleared the accident airplane to land, but did not provide sequencing instructions. The accident airplane then proceeded directly to a right-base entry into the traffic pattern for landing on Runway 9R.”

Unless sequencing information is included, pilots understand they are number one for the runway when a landing clearance is received and previous instructions don’t apply. Even though ATC attempted to call the accident pilot’s attention to the SR20, the record doesn’t show he ever knew it was there until the last moment. Then, he overreacted. In this case, the pilot attempted to do exactly as he was told by ATC.

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